1
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Goodwin MJ, Dickenson JC, Ripak A, Deetz AM, McCarthy JS, Meyer GJ, Troian-Gautier L. Factors that Impact Photochemical Cage Escape Yields. Chem Rev 2024. [PMID: 38743869 DOI: 10.1021/acs.chemrev.3c00930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The utilization of visible light to mediate chemical reactions in fluid solutions has applications that range from solar fuel production to medicine and organic synthesis. These reactions are typically initiated by electron transfer between a photoexcited dye molecule (a photosensitizer) and a redox-active quencher to yield radical pairs that are intimately associated within a solvent cage. Many of these radicals undergo rapid thermodynamically favored "geminate" recombination and do not diffuse out of the solvent cage that surrounds them. Those that do escape the cage are useful reagents that may undergo subsequent reactions important to the above-mentioned applications. The cage escape process and the factors that determine the yields remain poorly understood despite decades of research motivated by their practical and fundamental importance. Herein, state-of-the-art research on light-induced electron transfer and cage escape that has appeared since the seminal 1972 review by J. P. Lorand entitled "The Cage Effect" is reviewed. This review also provides some background for those new to the field and discusses the cage escape process of both homolytic bond photodissociation and bimolecular light induced electron transfer reactions. The review concludes with some key goals and directions for future research that promise to elevate this very vibrant field to even greater heights.
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Affiliation(s)
- Matthew J Goodwin
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - John C Dickenson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Alexia Ripak
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Alexander M Deetz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jackson S McCarthy
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Ludovic Troian-Gautier
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
- Wel Research Institute, Avenue Pasteur 6, 1300 Wavre, Belgium
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2
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Chung T, McClain TP, Alonso-Mori R, Chollet M, Deb A, Garcia-Esparza AT, Huang Ze En J, Lamb RM, Michocki LB, Reinhard M, van Driel TB, Penner-Hahn JE, Sension RJ. Ultrafast X-ray Absorption Spectroscopy Reveals Excited-State Dynamics of B 12 Coenzymes Controlled by the Axial Base. J Phys Chem B 2024; 128:1428-1437. [PMID: 38301132 DOI: 10.1021/acs.jpcb.3c07779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Polarized time-resolved X-ray absorption spectroscopy at the Co K-edge is used to probe the excited-state dynamics and photolysis of base-off methylcobalamin and the excited-state structure of base-off adenosylcobalamin. For both molecules, the final excited-state minimum shows evidence for an expansion of the cavity around the Co ion by ca. 0.04 to 0.05 Å. The 5-coordinate base-off cob(II)alamin that is formed following photodissociation has a structure similar to that of the 5-coordinate base-on cob(II)alamin, with a ring expansion of 0.03 to 0.04 Å and a contraction of the lower axial bond length relative to that in the 6-coordinate ground state. These data provide insights into the role of the lower axial ligand in modulating the reactivity of B12 coenzymes.
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Affiliation(s)
- Taewon Chung
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Taylor P McClain
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Matthieu Chollet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Angel T Garcia-Esparza
- Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025-7015, United States
| | - Joel Huang Ze En
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Ryan M Lamb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Lindsay B Michocki
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Marco Reinhard
- Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025-7015, United States
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - James E Penner-Hahn
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roseanne J Sension
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
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3
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Camacho IS, Wall E, Sazanovich IV, Gozzard E, Towrie M, Hunt NT, Hay S, Jones AR. Tuning of B 12 photochemistry in the CarH photoreceptor to avoid radical photoproducts. Chem Commun (Camb) 2023; 59:13014-13017. [PMID: 37831010 DOI: 10.1039/d3cc03900e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Time-resolved infrared spectroscopy reveals the flow of electron density through coenzyme B12 in the light-activated, bacterial transcriptional regulator, CarH. The protein stabilises a series of charge transfer states that result in a photoresponse that avoids reactive, and potentially damaging, radical photoproducts.
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Affiliation(s)
- Ines S Camacho
- Biometrology, Chemical and Biological Sciences Department, National Physical Laboratory, Teddington, Middlesex, UK.
| | - Emma Wall
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, UK
| | - Igor V Sazanovich
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, UK
| | - Emma Gozzard
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, UK
| | - Mike Towrie
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, UK
| | - Neil T Hunt
- Department of Chemistry and York Biomedical Research Institute, University of York, UK
| | - Sam Hay
- Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, 131 Princess Street, Manchester, UK
| | - Alex R Jones
- Biometrology, Chemical and Biological Sciences Department, National Physical Laboratory, Teddington, Middlesex, UK.
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4
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Sension RJ, McClain TP, Lamb RM, Alonso-Mori R, Lima FA, Ardana-Lamas F, Biednov M, Chollet M, Chung T, Deb A, Dewan PA, Gee LB, Huang Ze En J, Jiang Y, Khakhulin D, Li J, Michocki LB, Miller NA, Otte F, Uemura Y, van Driel TB, Penner-Hahn JE. Watching Excited State Dynamics with Optical and X-ray Probes: The Excited State Dynamics of Aquocobalamin and Hydroxocobalamin. J Am Chem Soc 2023. [PMID: 37327324 DOI: 10.1021/jacs.3c04099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Femtosecond time-resolved X-ray absorption (XANES) at the Co K-edge, X-ray emission (XES) in the Co Kβ and valence-to-core regions, and broadband UV-vis transient absorption are combined to probe the femtosecond to picosecond sequential atomic and electronic dynamics following photoexcitation of two vitamin B12 compounds, hydroxocobalamin and aquocobalamin. Polarized XANES difference spectra allow identification of sequential structural evolution involving first the equatorial and then the axial ligands, with the latter showing rapid coherent bond elongation to the outer turning point of the excited state potential followed by recoil to a relaxed excited state structure. Time-resolved XES, especially in the valence-to-core region, along with polarized optical transient absorption suggests that the recoil results in the formation of a metal-centered excited state with a lifetime of 2-5 ps. This combination of methods provides a uniquely powerful tool to probe the electronic and structural dynamics of photoactive transition-metal complexes and will be applicable to a wide variety of systems.
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Affiliation(s)
- Roseanne J Sension
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
| | - Taylor P McClain
- Department of Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Ryan M Lamb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Frederico Alves Lima
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Fernando Ardana-Lamas
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Mykola Biednov
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Matthieu Chollet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Taewon Chung
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department of Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Paul A Dewan
- Department of Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Leland B Gee
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Joel Huang Ze En
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Yifeng Jiang
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Dmitry Khakhulin
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Jianhao Li
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Lindsay B Michocki
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Nicholas A Miller
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Florian Otte
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Yohei Uemura
- Femtosecond X-ray Experiments Group, European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - James E Penner-Hahn
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department of Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
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5
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Toda MJ, Lodowski P, Mamun AA, Kozlowski PM. Photoproduct formation in coenzyme B 12-dependent CarH via a singlet pathway. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 232:112471. [PMID: 35644067 DOI: 10.1016/j.jphotobiol.2022.112471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/26/2022] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
The CarH photoreceptor exploits of the light-sensing ability of coenzyme B12 ( adenosylcobalamin = AdoCbl) to perform its catalytic function, which includes large-scale structural changes to regulate transcription. In daylight, transcription is activated in CarH via the photo-cleavage of the Co-C5' bond of coenzyme B12. Subsequently, the photoproduct, 4',5'-anhydroadenosine (anhAdo) is formed inducing dissociation of the CarH tetramer from DNA. Several experimental studies have proposed that hydridocoblamin (HCbl) may be formed in process with anhAdo. The photolytic cleavage of the Co-C5' bond of AdoCbl was previously investigated using photochemical techniques and the involvement of both singlet and triplet excited states were explored. Herein, QM/MM calculations were employed to probe (1) the photolytic processes which may involve singlet excited states, (2) the mechanism of anhAdo formation, and (3) whether HCbl is a viable intermediate in CarH. Time-dependent density functional theory (TD-DFT) calculations indicate that the mechanism of photodissociation of the Ado ligand involves the ligand field (LF) portion of the lowest singlet excited state (S1) potential energy surface (PES). This is followed by deactivation to a point on the S0 PES where the Co-C5' bond remains broken. This species corresponds to a singlet diradical intermediate. From this point, the PES for anhAdo formation was explored, using the Co-C5' and Co-C4' bond distances as active coordinates, and a local minimum representing anhAdo and HCbl formation was found. The transition state (TS) for the formation of the Co-H bond of HCbl was located and its identity was confirmed by a single imaginary frequency of i1592 cm-1. Comparisons to experimental studies and the potential role of rotation around the N-glycosidic bond of the Ado ligand were discussed.
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Affiliation(s)
- Megan J Toda
- Department of Chemistry, University of Louisville, Louisville, KY 40292, United States
| | - Piotr Lodowski
- Institute of Chemistry, Faculty of Science and Technology, University of Silesia in Katowice, Szkolna 9, PL-40 006 Katowice, Poland
| | - Abdullah Al Mamun
- Department of Chemistry, University of Louisville, Louisville, KY 40292, United States
| | - Pawel M Kozlowski
- Department of Chemistry, University of Louisville, Louisville, KY 40292, United States.
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6
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Ghosh AP, Lodowski P, Kozlowski PM. Aerobic photolysis of methylcobalamin: unraveling the photoreaction mechanism. Phys Chem Chem Phys 2022; 24:6093-6106. [PMID: 35212341 DOI: 10.1039/d1cp02013g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photo-reactivity of cobalamins (Cbls) is influenced by the nature of axial ligands and the cofactor's environment. While the biologically active forms of Cbls with alkyl axial ligands, such as methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), are considered to be photolytically active, in contrast, the non-alkyl Cbls are photostable. In addition to these, the photolytic properties of Cbls can also be modulated in the presence of molecular oxygen, i.e., under aerobic conditions. Herein, the photoreaction of the MeCbl in the presence of oxygen has been explored using density functional theory (DFT) and time-dependent DFT (TD-DFT). The first stage of the aerobic photoreaction is the activation of the Co-C bond and the formation of the ligand field (LF) electronic state through the displacement of axial bonds. Once the photoreaction reaches the LF excited state, three processes can occur: namely the formation of OO-CH3 through the reaction of CH3 with molecular oxygen, de-activation of the {Im⋯[CoII(corrin)]⋯CH3}+ sub-system from the LF electronic state by changing the electronic configuration from (dyz)1(dz2)2 to (dyz)2(dz2)1 and the formation of the deactivation complex (DC) complex via the recombination of OO-CH3 species with the de-excited [CoII(corrin)] system. In the proposed mechanism, the deactivation of the [CoII(corrin)] subsystem may coexist with the formation of OO-CH3, followed by immediate relaxation of the subsystems in the ground state. Moreover, the formation of the OO-CH3 species followed by the formation of the {[CoIII(corrin)]-OO-CH3}+ complex stabilizes the system compared to the reactant complex.
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Affiliation(s)
- Arghya Pratim Ghosh
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
| | - Piotr Lodowski
- Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, PL-40 006 Katowice, Poland
| | - Pawel M Kozlowski
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
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7
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Ghosh AP, Toda MJ, Kozlowski PM. Photolytic properties of B 12-dependent enzymes: A theoretical perspective. VITAMINS AND HORMONES 2022; 119:185-220. [PMID: 35337619 DOI: 10.1016/bs.vh.2022.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The biologically active vitamin B12 derivates, methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), are ubiquitous organometallic cofactors. In addition to their key roles in enzymatic catalysis, B12 cofactors have complex photolytic properties which have been the target of experimental and theoretical studies. With the recent discovery of B12-dependent photoreceptors, there is an increased need to elucidate the underlying photochemical mechanisms of these systems. This book chapter summarizes the photolytic properties of MeCbl- and AdoCbl-dependent enzymes with particular emphasis on the effect of the environment of the cofactor on the excited state processes. These systems include isolated MeCbl and AdoCbl as well as the enzymes, ethanolamine ammonia-lyase (EAL), glutamate mutase (GLM), methionine synthase (MetH), and photoreceptor CarH. Central to determining the photodissociation mechanism of each system is the analysis of the lowest singlet excited state (S1) potential energy surface (PES). Time-dependent density functional theory (TD-DFT), employing BP86/TZVPP, is widely used to construct such PESs. Regardless of the environment, the topology of the S1 PES of AdoCbl or MeCbl is marked by characteristic features, namely the metal-to-ligand charge transfer (MLCT) and ligand field (LF) regions. Conversely, the relative energetics of these electronic states are affected by the environment. Applications and outlooks for Cbl photochemistry are also discussed.
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Affiliation(s)
- Arghya Pratim Ghosh
- Department of Chemistry, University of Louisville, Louisville, KY, United States
| | - Megan J Toda
- Department of Chemistry, University of Louisville, Louisville, KY, United States
| | - Pawel M Kozlowski
- Department of Chemistry, University of Louisville, Louisville, KY, United States.
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8
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Sension RJ, Chung T, Dewan P, McClain TP, Lamb RM, Penner-Hahn JE. Time-resolved spectroscopy: Advances in understanding the electronic structure and dynamics of cobalamins. Methods Enzymol 2022; 669:303-331. [DOI: 10.1016/bs.mie.2022.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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9
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Weinstain R, Slanina T, Kand D, Klán P. Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials. Chem Rev 2020; 120:13135-13272. [PMID: 33125209 PMCID: PMC7833475 DOI: 10.1021/acs.chemrev.0c00663] [Citation(s) in RCA: 242] [Impact Index Per Article: 60.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Indexed: 02/08/2023]
Abstract
Photoactivatable (alternatively, photoremovable, photoreleasable, or photocleavable) protecting groups (PPGs), also known as caged or photocaged compounds, are used to enable non-invasive spatiotemporal photochemical control over the release of species of interest. Recent years have seen the development of PPGs activatable by biologically and chemically benign visible and near-infrared (NIR) light. These long-wavelength-absorbing moieties expand the applicability of this powerful method and its accessibility to non-specialist users. This review comprehensively covers organic and transition metal-containing photoactivatable compounds (complexes) that absorb in the visible- and NIR-range to release various leaving groups and gasotransmitters (carbon monoxide, nitric oxide, and hydrogen sulfide). The text also covers visible- and NIR-light-induced photosensitized release using molecular sensitizers, quantum dots, and upconversion and second-harmonic nanoparticles, as well as release via photodynamic (photooxygenation by singlet oxygen) and photothermal effects. Release from photoactivatable polymers, micelles, vesicles, and photoswitches, along with the related emerging field of photopharmacology, is discussed at the end of the review.
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Affiliation(s)
- Roy Weinstain
- School
of Plant Sciences and Food Security, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 6997801, Israel
| | - Tomáš Slanina
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague, Czech Republic
| | - Dnyaneshwar Kand
- School
of Plant Sciences and Food Security, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 6997801, Israel
| | - Petr Klán
- Department
of Chemistry and RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
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10
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Miller NA, Kaneshiro AK, Konar A, Alonso-Mori R, Britz A, Deb A, Glownia JM, Koralek JD, Mallik L, Meadows JH, Michocki LB, van Driel TB, Koutmos M, Padmanabhan S, Elías-Arnanz M, Kubarych KJ, Marsh ENG, Penner-Hahn JE, Sension RJ. The Photoactive Excited State of the B 12-Based Photoreceptor CarH. J Phys Chem B 2020; 124:10732-10738. [PMID: 33174757 DOI: 10.1021/acs.jpcb.0c09428] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have used transient absorption spectroscopy in the UV-visible and X-ray regions to characterize the excited state of CarH, a protein photoreceptor that uses a form of B12, adenosylcobalamin (AdoCbl), to sense light. With visible excitation, a nanosecond-lifetime photoactive excited state is formed with unit quantum yield. The time-resolved X-ray absorption near edge structure difference spectrum of this state demonstrates that the excited state of AdoCbl in CarH undergoes only modest structural expansion around the central cobalt, a behavior similar to that observed for methylcobalamin rather than for AdoCbl free in solution. We propose a new mechanism for CarH photoreactivity involving formation of a triplet excited state. This allows the sensor to operate with high quantum efficiency and without formation of potentially dangerous side products. By stabilizing the excited electronic state, CarH controls reactivity of AdoCbl and enables slow reactions that yield nonreactive products and bypass bond homolysis and reactive radical species formation.
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Affiliation(s)
- Nicholas A Miller
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - April K Kaneshiro
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Dr., Ann Arbor, Michigan 48109-0600, United States
| | - Arkaprabha Konar
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Alexander Britz
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States.,Stanford PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States.,Department of Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - James M Glownia
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Jake D Koralek
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Leena Mallik
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Joseph H Meadows
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Lindsay B Michocki
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Markos Koutmos
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States.,Department of Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - S Padmanabhan
- Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid 28006, Spain
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas), Facultad de Biología, Universidad de Murcia, Murcia 30100, Spain
| | - Kevin J Kubarych
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - E Neil G Marsh
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - James E Penner-Hahn
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States.,Department of Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
| | - Roseanne J Sension
- Department of Chemistry, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States.,Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States.,Department of Biophysics, University of Michigan, 930 N University Ave. Ann Arbor, Michigan 48109-1055, United States
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11
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Toda MJ, Mamun AA, Lodowski P, Kozlowski PM. Why is CarH photolytically active in comparison to other B12-dependent enzymes? JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2020; 209:111919. [DOI: 10.1016/j.jphotobiol.2020.111919] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 05/21/2020] [Accepted: 05/22/2020] [Indexed: 12/23/2022]
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12
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Ghosh AP, Lodowski P, Bazarganpour A, Leks M, Kozlowski PM. Aerobic photolysis of methylcobalamin: structural and electronic properties of the Cbl-O-O-CH 3 intermediate. Dalton Trans 2020; 49:4114-4124. [PMID: 32142090 DOI: 10.1039/c9dt03740c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Photolysis of methylcobalamin (MeCbl) in the presence of molecular oxygen (O2) has been investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT). The key step involves the formation of the Cbl-O-O-CH3 intermediate as a result of triplet O2 insertion in the Co-C bond in the presence of light. Analysis of low-lying excited states shows that the presence of light is only needed to activate the Co-C bond via the formation of the ligand field (LF) state. The insertion of O2, as well as the change in the spin state, takes place in the ground state. The analysis of the structural and electronic properties of the Cbl-O-O-CH3 intermediate is presented and possible decomposition also discussed.
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Affiliation(s)
- Arghya Pratim Ghosh
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
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13
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Lukinović V, Woodward JR, Marrafa TC, Shanmugam M, Heyes DJ, Hardman SJO, Scrutton NS, Hay S, Fielding AJ, Jones AR. Photochemical Spin Dynamics of the Vitamin B 12 Derivative, Methylcobalamin. J Phys Chem B 2019; 123:4663-4672. [PMID: 31081330 DOI: 10.1021/acs.jpcb.9b01969] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Derivatives of vitamin B12 are six-coordinate cobalt corrinoids found in humans, other animals, and microorganisms. By acting as enzymatic cofactors and photoreceptor chromophores, they serve vital metabolic and photoprotective functions. Depending on the context, the chemical mechanisms of the biologically active derivatives of B12-methylcobalamin (MeCbl) and 5'-deoxyadenosylcobalamin (AdoCbl)-can be very different from one another. The extent to which this chemistry is tuned by the upper axial ligand, however, is not yet clear. Here, we have used a combination of time-resolved Fourier transform-electron paramagnetic resonance (FT-EPR), magnetic field effect experiments, and spin dynamic simulations to reveal that the upper axial ligand alone only results in relatively minor changes to the photochemical spin dynamics of B12. By studying the photolysis of MeCbl, we find that, similar to AdoCbl, the initial (or "geminate") radical pairs (RPs) are born predominantly in the singlet spin state and thus originate from singlet excited-state precursors. This is in contrast to the triplet RPs and precursors proposed previously. Unlike AdoCbl, the extent of geminate recombination is limited following MeCbl photolysis, resulting in significant distortions to the FT-EPR signal caused by polarization from spin-correlated methyl-methyl radical "f-pairs" formed following rapid diffusion. Despite the photophysical mechanism that precedes photolysis of MeCbl showing wavelength dependence, the subsequent spin dynamics appear to be largely independent of excitation wavelength, again similar to AdoCbl. Our data finally provide clarity to what in the literature to date has been a confused and contradictory picture. We conclude that, although the upper axial position of MeCbl and AdoCbl does impact their reactivity to some extent, the remarkable biochemical diversity of these fascinating molecules is most likely a result of tuning by their protein environment.
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Affiliation(s)
- Valentina Lukinović
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Jonathan R Woodward
- Graduate School of Arts and Sciences , The University of Tokyo , 3-8-1 Komaba , Meguro-ku, Tokyo 153-8902 , Japan
| | - Teresa C Marrafa
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Muralidharan Shanmugam
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Derren J Heyes
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Samantha J O Hardman
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Sam Hay
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | | | - Alex R Jones
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
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14
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Toda MJ, Lodowski P, Mamun AA, Jaworska M, Kozlowski PM. Photolytic properties of the biologically active forms of vitamin B12. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2018.12.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Mamun AA, Toda MJ, Lodowski P, Kozlowski PM. Photolytic Cleavage of Co–C Bond in Coenzyme B12-Dependent Glutamate Mutase. J Phys Chem B 2019; 123:2585-2598. [DOI: 10.1021/acs.jpcb.8b07547] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Abdullah Al Mamun
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Megan J. Toda
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Piotr Lodowski
- Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, PL-40 006 Katowice, Poland
| | - Pawel M. Kozlowski
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
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16
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Mamun AA, Toda MJ, Kozlowski PM. Can photolysis of the Co C bond in coenzyme B12-dependent enzymes be used to mimic the native reaction? JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2019; 191:175-184. [DOI: 10.1016/j.jphotobiol.2018.12.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 12/22/2022]
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17
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Ghosh AP, Mamun AA, Lodowski P, Jaworska M, Kozlowski PM. Mechanism of the photo-induced activation of Co C bond in methylcobalamin-dependent methionine synthase. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2018; 189:306-317. [DOI: 10.1016/j.jphotobiol.2018.09.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/12/2018] [Accepted: 09/18/2018] [Indexed: 11/26/2022]
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18
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Vaid FH, Zahid S, Faiyaz A, Qadeer K, Gul W, Anwar Z, Ahmad I. Photolysis of methylcobalamin in aqueous solution: A kinetic study. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2018.05.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Mamun AA, Toda MJ, Lodowski P, Jaworska M, Kozlowski PM. Mechanism of Light Induced Radical Pair Formation in Coenzyme B12-Dependent Ethanolamine Ammonia-Lyase. ACS Catal 2018. [DOI: 10.1021/acscatal.8b00120] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Abdullah Al Mamun
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Megan J. Toda
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Piotr Lodowski
- Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, PL-40 006 Katowice, Poland
| | - Maria Jaworska
- Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, PL-40 006 Katowice, Poland
| | - Pawel M. Kozlowski
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
- Department of Food Sciences, Medical University of Gdansk, Al. Gen. J. Hallera 107, 80-416 Gdansk, Poland
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20
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Padmanabhan S, Jost M, Drennan CL, Elías-Arnanz M. A New Facet of Vitamin B 12: Gene Regulation by Cobalamin-Based Photoreceptors. Annu Rev Biochem 2017; 86:485-514. [PMID: 28654327 PMCID: PMC7153952 DOI: 10.1146/annurev-biochem-061516-044500] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Living organisms sense and respond to light, a crucial environmental factor, using photoreceptors, which rely on bound chromophores such as retinal, flavins, or linear tetrapyrroles for light sensing. The discovery of photoreceptors that sense light using 5'-deoxyadenosylcobalamin, a form of vitamin B12 that is best known as an enzyme cofactor, has expanded the number of known photoreceptor families and unveiled a new biological role of this vitamin. The prototype of these B12-dependent photoreceptors, the transcriptional repressor CarH, is widespread in bacteria and mediates light-dependent gene regulation in a photoprotective cellular response. CarH activity as a transcription factor relies on the modulation of its oligomeric state by 5'-deoxyadenosylcobalamin and light. This review surveys current knowledge about these B12-dependent photoreceptors, their distribution and mode of action, and the structural and photochemical basis of how they orchestrate signal transduction and control gene expression.
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Affiliation(s)
- S Padmanabhan
- Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain;
| | - Marco Jost
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94158-2140;
| | - Catherine L Drennan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Department of Biology and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139;
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética, Unidad Asociada al Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain;
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21
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Miller NA, Deb A, Alonso-Mori R, Garabato BD, Glownia JM, Kiefer LM, Koralek J, Sikorski M, Spears KG, Wiley TE, Zhu D, Kozlowski PM, Kubarych KJ, Penner-Hahn JE, Sension RJ. Polarized XANES Monitors Femtosecond Structural Evolution of Photoexcited Vitamin B12. J Am Chem Soc 2017; 139:1894-1899. [DOI: 10.1021/jacs.6b11295] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Nicholas A. Miller
- Department
of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Aniruddha Deb
- Department
of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roberto Alonso-Mori
- Linac
Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand
Hill Road, Menlo Park, California 94025, United States,
| | - Brady D. Garabato
- Department
of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, United States
| | - James M. Glownia
- Linac
Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand
Hill Road, Menlo Park, California 94025, United States,
| | - Laura M. Kiefer
- Department
of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Jake Koralek
- Linac
Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand
Hill Road, Menlo Park, California 94025, United States,
| | - Marcin Sikorski
- Linac
Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand
Hill Road, Menlo Park, California 94025, United States,
| | - Kenneth G. Spears
- Department
of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Theodore E. Wiley
- Department
of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Diling Zhu
- Linac
Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand
Hill Road, Menlo Park, California 94025, United States,
| | - Pawel M. Kozlowski
- Department
of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, United States
- Department
of Food Sciences, Medical University of Gdansk, Al. Gen J. Hallera
107, 80-416 Gdansk, Poland
| | - Kevin J. Kubarych
- Department
of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - James E. Penner-Hahn
- Department
of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roseanne J. Sension
- Department
of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
- Department
of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
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22
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Abstract
This Perspective provides the first detailed overview of the photoresponse of vitamin B12 and its derivatives, from the early, photophysical events to the burgeoning area of B12-dependent photobiology.
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Affiliation(s)
- Alex R. Jones
- School of Chemistry
- Photon Science Institute and Manchester Institute of Biotechnology
- The University of Manchester
- Manchester
- UK
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23
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Huang X, Groves JT. Beyond ferryl-mediated hydroxylation: 40 years of the rebound mechanism and C-H activation. J Biol Inorg Chem 2016; 22:185-207. [PMID: 27909920 PMCID: PMC5350257 DOI: 10.1007/s00775-016-1414-3] [Citation(s) in RCA: 195] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/03/2016] [Indexed: 11/24/2022]
Abstract
Since our initial report in 1976, the oxygen rebound mechanism has become the consensus mechanistic feature for an expanding variety of enzymatic C-H functionalization reactions and small molecule biomimetic catalysts. For both the biotransformations and models, an initial hydrogen atom abstraction from the substrate (R-H) by high-valent iron-oxo species (Fen=O) generates a substrate radical and a reduced iron hydroxide, [Fen-1-OH ·R]. This caged radical pair then evolves on a complicated energy landscape through a number of reaction pathways, such as oxygen rebound to form R-OH, rebound to a non-oxygen atom affording R-X, electron transfer of the incipient radical to yield a carbocation, R+, desaturation to form olefins, and radical cage escape. These various flavors of the rebound process, often in competition with each other, give rise to the wide range of C-H functionalization reactions performed by iron-containing oxygenases. In this review, we first recount the history of radical rebound mechanisms, their general features, and key intermediates involved. We will discuss in detail the factors that affect the behavior of the initial caged radical pair and the lifetimes of the incipient substrate radicals. Several representative examples of enzymatic C-H transformations are selected to illustrate how the behaviors of the radical pair [Fen-1-OH ·R] determine the eventual reaction outcome. Finally, we discuss the powerful potential of "radical rebound" processes as a general paradigm for developing novel C-H functionalization reactions with synthetic, biomimetic catalysts. We envision that new chemistry will continue to arise by bridging enzymatic "radical rebound" with synthetic organic chemistry.
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24
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Miller NA, Wiley TE, Spears KG, Ruetz M, Kieninger C, Kräutler B, Sension RJ. Toward the Design of Photoresponsive Conditional Antivitamins B12: A Transient Absorption Study of an Arylcobalamin and an Alkynylcobalamin. J Am Chem Soc 2016; 138:14250-14256. [DOI: 10.1021/jacs.6b05299] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Nicholas A. Miller
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Theodore E. Wiley
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Kenneth G. Spears
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Markus Ruetz
- Institute of Organic Chemistry & Center for Molecular Biosciences, University of Innsbruck, Innrain 80/82, A-6020 Innsbruck, Austria
| | - Christoph Kieninger
- Institute of Organic Chemistry & Center for Molecular Biosciences, University of Innsbruck, Innrain 80/82, A-6020 Innsbruck, Austria
| | - Bernhard Kräutler
- Institute of Organic Chemistry & Center for Molecular Biosciences, University of Innsbruck, Innrain 80/82, A-6020 Innsbruck, Austria
| | - Roseanne J. Sension
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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25
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Garabato BD, Lodowski P, Jaworska M, Kozlowski PM. Mechanism of Co-C photodissociation in adenosylcobalamin. Phys Chem Chem Phys 2016; 18:19070-82. [PMID: 27356617 DOI: 10.1039/c6cp02136k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A mechanism of Co-C bond photodissociation in the base-on form of adenosylcobalamin (AdoCbl) was investigated by time-dependent density functional theory (TD-DFT). The key mechanistic step involves singlet radical pair (RP) generation from the first electronically excited state (S1). To connect TD-DFT calculations with ultra-fast excited state dynamics, the potential energy surface (PES) of the S1 state was constructed using Co-C and Co-NIm axial coordinates. The S1 PES can be characterized by two minima separated by a seam resulting from the crossing of two surfaces, of metal-to-ligand charge transfer (MLCT) character near the minimum, and a shallow ligand field (LF) surface at elongated axial bond distances. Only one possible pathway for photolysis (path A) was identified based on energetic grounds. This pathway is characterized by the first elongation of the Co-C bond, followed by photolysis from an LF state where the axial base is partially detached. A new perspective on the photolysis of AdoCbl is then gained by connecting TD-DFT results with available experimental observations.
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Affiliation(s)
- Brady D Garabato
- Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40202, USA.
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26
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Kozlowski PM, Garabato BD, Lodowski P, Jaworska M. Photolytic properties of cobalamins: a theoretical perspective. Dalton Trans 2016; 45:4457-70. [PMID: 26865262 DOI: 10.1039/c5dt04286k] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This Perspective Article highlights recent theoretical developments, and summarizes the current understanding of the photolytic properties of cobalamins from a computational point of view. The primary focus is on two alkyl cobalamins, methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), as well as two non-alkyl cobalamins, cyanocobalamin (CNCbl) and hydroxocobalamin (HOCbl). Photolysis of alkyl cobalamins involves low-lying singlet excited states where photodissociation of the Co-C bond leads to formation of singlet-born alkyl/cob(ii)alamin radical pairs (RPs). Potential energy surfaces (PESs) associated with cobalamin low-lying excited states as functions of both axial bonds, provide the most reliable tool for initial analysis of their photochemical and photophysical properties. Due to the complexity, and size limitations associated with the cobalamins, the primary method for calculating ground state properties is density functional theory (DFT), while time-dependent DFT (TD-DFT) is used for electronically excited states. For alkyl cobalamins, energy pathways on the lowest singlet surface, connecting metal-to-ligand charge transfer (MLCT) and ligand field (LF) minima, can be associated with photo-homolysis of the Co-C bond observed experimentally. Additionally, energy pathways between minima and seams associated with crossing of S1/S0 surfaces, are the most efficient for internal conversion (IC) to the ground state. Depending on the specific cobalamin, such IC may involve simultaneous elongation of both axial bonds (CNCbl), or detachment of axial base followed by corrin ring distortion (MeCbl). The possibility of intersystem crossing, and the formation of triplet RPs is also discussed based on Landau-Zener theory.
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Affiliation(s)
- Pawel M Kozlowski
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
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27
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Garabato BD, Kumar N, Lodowski P, Jaworska M, Kozlowski PM. Electronically excited states of cob(ii)alamin: insights from CASSCF/XMCQDPT2 and TD-DFT calculations. Phys Chem Chem Phys 2016; 18:4513-26. [DOI: 10.1039/c5cp06439b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The low-lying excited states of cob(ii)alamin were investigated using time-dependent density functional theory (TD-DFT), and multiconfigurational CASSCF/XMCQDPT2 methodology, to help understand their role in B12-mediated reactions.
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Affiliation(s)
| | - Neeraj Kumar
- Department of Chemistry
- University of Louisville
- Louisville
- USA
- Pacific Northwest National Laboratory
| | - Piotr Lodowski
- Department of Theoretical Chemistry
- Institute of Chemistry
- University of Silesia
- PL-40 006 Katowice
- Poland
| | - Maria Jaworska
- Department of Theoretical Chemistry
- Institute of Chemistry
- University of Silesia
- PL-40 006 Katowice
- Poland
| | - Pawel M. Kozlowski
- Department of Chemistry
- University of Louisville
- Louisville
- USA
- Visiting Professor at the Department of Food Sciences
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28
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The photochemical mechanism of a B12-dependent photoreceptor protein. Nat Commun 2015; 6:7907. [PMID: 26264192 PMCID: PMC4557120 DOI: 10.1038/ncomms8907] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 06/23/2015] [Indexed: 01/01/2023] Open
Abstract
The coenzyme B12-dependent photoreceptor protein, CarH, is a bacterial transcriptional regulator that controls the biosynthesis of carotenoids in response to light. On binding of coenzyme B12 the monomeric apoprotein forms tetramers in the dark, which bind operator DNA thus blocking transcription. Under illumination the CarH tetramer dissociates, weakening its affinity for DNA and allowing transcription. The mechanism by which this occurs is unknown. Here we describe the photochemistry in CarH that ultimately triggers tetramer dissociation; it proceeds via a cob(III)alamin intermediate, which then forms a stable adduct with the protein. This pathway is without precedent and our data suggest it is independent of the radical chemistry common to both coenzyme B12 enzymology and its known photochemistry. It provides a mechanistic foundation for the emerging field of B12 photobiology and will serve to inform the development of a new class of optogenetic tool for the control of gene expression. Coenzyme B12 traditionally acts as cofactor to light-independent metabolic enzymes in bacteria and humans. Here, Kutta et al. present a time-resolved photochemical description of a B12-dependent photoreceptor protein, which represents a mechanistic foundation for B12 photobiology.
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29
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Jost M, Simpson JH, Drennan CL. The Transcription Factor CarH Safeguards Use of Adenosylcobalamin as a Light Sensor by Altering the Photolysis Products. Biochemistry 2015; 54:3231-4. [PMID: 25966286 PMCID: PMC4455981 DOI: 10.1021/acs.biochem.5b00416] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The newly discovered light-dependent
transcription factor CarH
uses adenosylcobalamin as a light sensor to regulate expression of
protective genes in bacteria upon exposure to sunlight. This use of
adenosylcobalamin is a clever adaptation of a classic enzyme cofactor,
taking advantage of its photolabile Co–C bond. However, it
is also puzzling in that photolysis of adenosylcobalamin generates
the 5′-deoxyadenosyl radical that could damage DNA. Here, using
liquid chromatography and spectroscopic techniques, we demonstrate
that CarH suppresses release of the 5′-deoxyadenosyl radical
and instead effects conversion to a nonreactive 4′,5′-anhydroadenosine.
In this manner, CarH safeguards use of adenosylcobalamin in light-dependent
gene regulation.
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Affiliation(s)
- Marco Jost
- †Department of Chemistry and ‡Department of Biology and Howard Hughes Medical Institute, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Jeffrey H Simpson
- †Department of Chemistry and ‡Department of Biology and Howard Hughes Medical Institute, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Catherine L Drennan
- †Department of Chemistry and ‡Department of Biology and Howard Hughes Medical Institute, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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30
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31
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Rury AS, Wiley TE, Sension RJ. Energy cascades, excited state dynamics, and photochemistry in cob(III)alamins and ferric porphyrins. Acc Chem Res 2015; 48:860-7. [PMID: 25741574 DOI: 10.1021/ar5004016] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Porphyrins and the related chlorins and corrins contain a cyclic tetrapyrrole with the ability to coordinate an active metal center and to perform a variety of functions exploiting the oxidation state, reactivity, and axial ligation of the metal center. These compounds are used in optically activated applications ranging from light harvesting and energy conversion to medical therapeutics and photodynamic therapy to molecular electronics, spintronics, optoelectronic thin films, and optomagnetics. Cobalt containing corrin rings extend the range of applications through photolytic cleavage of a unique axial carbon-cobalt bond, permitting spatiotemporal control of drug delivery. The photochemistry and photophysics of cyclic tetrapyrroles are controlled by electronic relaxation dynamics including internal conversion and intersystem crossing. Typically the electronic excitation cascades through ring centered ππ* states, ligand to metal charge transfer (LMCT) states, metal to ligand charge transfer (MLCT) states, and metal centered states. Ultrafast transient absorption spectroscopy provides a powerful tool for the investigation of the electronic state dynamics in metal containing tetrapyrroles. The UV-visible spectrum is sensitive to the oxidation state, electronic configuration, spin state, and axial ligation of the central metal atom. Ultrashort broadband white light probes spanning the range from 270 to 800 nm, combined with tunable excitation pulses, permit the detailed unravelling of the time scales involved in the electronic energy cascade. State-of-the-art theoretical calculations provide additional insight required for precise assignment of the states. In this Account, we focus on recent ultrafast transient absorption studies of ferric porphyrins and corrin containing cob(III)alamins elucidating the electronic states responsible for ultrafast energy cascades, excited state dynamics, and the resulting photoreactivity or photostability of these compounds. Iron tetraphenyl porphyrin chloride (Fe((III))TPPCl) exhibits picosecond decay to a metal centered d → d* (4)T state. This state decays on a ca. 16 ps time scale in room temperature solution but persists for much longer in a cryogenic glass. The photoreactivity of the (4)T state may lead to novel future applications for these compounds. In contrast, the nonplanar cob(III)alamins contain two axial ligands to the central cobalt atom. The upper axial ligand can be an alkyl group as in the two biologically active coenzymes or a nonalkyl ligand such as -CN in cyanocobalamin (vitamin B12) or -OH in hydroxocobalamin. The electronic structure, energy cascade, and bond cleavage of these compounds is sensitive to the details of the axial ligand. Nonalkylcobalamins exhibit ultrafast internal conversion to a low-lying state of metal to ligand or ligand to metal charge transfer character. The compounds are generally photostable with ground state recovery complete on a time scale of 2-7 ps in room temperature aqueous solution. Alkylcobalamins exhibit ultrafast internal conversion to an S1 state of d/π → π* character. Most compounds undergo bond cleavage from this state with near unit quantum yield within ∼100 ps. Recent theoretical calculations provide a potential energy surface accounting for these observations. Conformation dependent mixing of the corrin π and cobalt d orbitals plays a significant role in the observed photochemistry and photophysics.
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Affiliation(s)
- Aaron S. Rury
- Department of Chemistry and
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Theodore E. Wiley
- Department of Chemistry and
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Roseanne J. Sension
- Department of Chemistry and
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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32
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Lodowski P, Jaworska M, Andruniów T, Garabato BD, Kozlowski PM. Mechanism of Co–C Bond Photolysis in the Base-On Form of Methylcobalamin. J Phys Chem A 2014; 118:11718-34. [DOI: 10.1021/jp508513p] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Piotr Lodowski
- Department
of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland
| | - Maria Jaworska
- Department
of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland
| | - Tadeusz Andruniów
- Institute
of Physical and Theoretical Chemistry, Department of Chemistry, Wroclaw University of Technology, 50-370 Wroclaw, Poland
| | - Brady D. Garabato
- Department
of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Pawel M. Kozlowski
- Department
of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
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33
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Liu H, Kornobis K, Lodowski P, Jaworska M, Kozlowski PM. TD-DFT insight into photodissociation of the Co-C bond in coenzyme B12. Front Chem 2014; 1:41. [PMID: 24790969 PMCID: PMC3982521 DOI: 10.3389/fchem.2013.00041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 12/24/2013] [Indexed: 11/30/2022] Open
Abstract
Coenzyme B12 (AdoCbl) is one of the most biologically active forms of vitamin B12, and continues to be a topic of active research interest. The mechanism of Co-C bond cleavage in AdoCbl, and the corresponding enzymatic reactions are however, not well understood at the molecular level. In this work, time-dependent density functional theory (TD-DFT) has been applied to investigate the photodissociation of coenzyme B12. To reduce computational cost, while retaining the major spectroscopic features of AdoCbl, a truncated model based on ribosylcobalamin (RibCbl) was used to simulate Co-C photodissociation. Equilibrium geometries of RibCbl were obtained by optimization at the DFT/BP86/TZVP level of theory, and low-lying excited states were calculated by TD-DFT using the same functional and basis set. The calculated singlet states, and absorption spectra were simulated in both the gas phase, and water, using the polarizable continuum model (PCM). Both spectra were in reasonable agreement with experimental data, and potential energy curves based on vertical excitations were plotted to explore the nature of Co-C bond dissociation. It was found that a repulsive 3(σCo−C → σ*Co−C) triplet state became dissociative at large Co-C bond distance, similar to a previous observation for methylcobalamin (MeCbl). Furthermore, potential energy surfaces (PESs) obtained as a function of both Co-CRib and Co-NIm distances, identify the S1 state as a key intermediate generated during photoexcitation of RibCbl, attributed to a mixture of a metal-to-ligand charge transfer (MLCT) and a σ bonding-ligand charge transfer (SBLCT) states.
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Affiliation(s)
- Hui Liu
- Department of Chemistry, University of Louisville Louisville, KY, USA
| | - Karina Kornobis
- Department of Chemistry, University of Louisville Louisville, KY, USA
| | - Piotr Lodowski
- Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia Katowice, Poland
| | - Maria Jaworska
- Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia Katowice, Poland
| | - Pawel M Kozlowski
- Department of Chemistry, University of Louisville Louisville, KY, USA
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34
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Lodowski P, Jaworska M, Andruniów T, Garabato BD, Kozlowski PM. Mechanism of the S1 excited state internal conversion in vitamin B12. Phys Chem Chem Phys 2014; 16:18675-9. [DOI: 10.1039/c4cp02465f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To explain the photostability of vitamin B12, internal conversion of the S1 state was investigated using TD-DFT.
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Affiliation(s)
- Piotr Lodowski
- Department of Theoretical Chemistry
- Institute of Chemistry
- University of Silesia
- PL-40 006 Katowice, Poland
| | - Maria Jaworska
- Department of Theoretical Chemistry
- Institute of Chemistry
- University of Silesia
- PL-40 006 Katowice, Poland
| | - Tadeusz Andruniów
- Institute of Physical and Theoretical Chemistry
- Department of Chemistry
- Wroclaw University of Technology
- 50-370 Wroclaw, Poland
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35
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Achey D, Brigham EC, DiMarco BN, Meyer GJ. Excited state electron transfer after visible light absorption by the Co(i) state of vitamin B12. Chem Commun (Camb) 2014; 50:13304-6. [DOI: 10.1039/c4cc02221a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Co(i) form of vitamin B12 was found to undergo excitation wavelength-dependent excited state electron transfer to TiO2.
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Affiliation(s)
- Darren Achey
- Department of Physical Sciences
- Kutztown University
- Kutztown, USA
- Department of Chemistry
- Johns Hopkins University
| | | | | | - Gerald J. Meyer
- Department of Chemistry
- Johns Hopkins University
- Baltimore, USA
- Department of Materials Science and Engineering
- Johns Hopkins University
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36
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Wang M, Warncke K. Entropic origin of cobalt-carbon bond cleavage catalysis in adenosylcobalamin-dependent ethanolamine ammonia-lyase. J Am Chem Soc 2013; 135:15077-84. [PMID: 24028405 PMCID: PMC3839591 DOI: 10.1021/ja404467d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Adenosylcobalamin-dependent enzymes accelerate the cleavage of the cobalt-carbon (Co-C) bond of the bound coenzyme by >10(10)-fold. The cleavage-generated 5'-deoxyadenosyl radical initiates the catalytic cycle by abstracting a hydrogen atom from substrate. Kinetic coupling of the Co-C bond cleavage and hydrogen-atom-transfer steps at ambient temperatures has interfered with past experimental attempts to directly address the factors that govern Co-C bond cleavage catalysis. Here, we use time-resolved, full-spectrum electron paramagnetic resonance spectroscopy, with temperature-step reaction initiation, starting from the enzyme-coenzyme-substrate ternary complex and (2)H-labeled substrate, to study radical pair generation in ethanolamine ammonia-lyase from Salmonella typhimurium at 234-248 K in a dimethylsulfoxide/water cryosolvent system. The monoexponential kinetics of formation of the (2)H- and (1)H-substituted substrate radicals are the same, indicating that Co-C bond cleavage rate-limits radical pair formation. Analysis of the kinetics by using a linear, three-state model allows extraction of the microscopic rate constant for Co-C bond cleavage. Eyring analysis reveals that the activation enthalpy for Co-C bond cleavage is 32 ± 1 kcal/mol, which is the same as for the cleavage reaction in solution. The origin of Co-C bond cleavage catalysis in the enzyme is, therefore, the large, favorable activation entropy of 61 ± 6 cal/(mol·K) (relative to 7 ± 1 cal/(mol·K) in solution). This represents a paradigm shift from traditional, enthalpy-based mechanisms that have been proposed for Co-C bond-breaking in B12 enzymes. The catalysis is proposed to arise from an increase in protein configurational entropy along the reaction coordinate.
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Affiliation(s)
- Miao Wang
- Department of Physics, Emory University, Atlanta, GA 30322, United States
- Current Address: Wilmad-LabGlass, 1172 NW Boulevard, Vineland, NJ 08360
| | - Kurt Warncke
- Department of Physics, Emory University, Atlanta, GA 30322, United States
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37
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Jones AR, Levy C, Hay S, Scrutton NS. Relating localized protein motions to the reaction coordinate in coenzyme B12-dependent enzymes. FEBS J 2013; 280:2997-3008. [DOI: 10.1111/febs.12223] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Revised: 02/27/2013] [Accepted: 02/27/2013] [Indexed: 01/27/2023]
Affiliation(s)
| | - Colin Levy
- Manchester Institute of Biotechnology and Faculty of Life Sciences; The University of Manchester; Manchester; UK
| | - Sam Hay
- Manchester Institute of Biotechnology and Faculty of Life Sciences; The University of Manchester; Manchester; UK
| | - Nigel S. Scrutton
- Manchester Institute of Biotechnology and Faculty of Life Sciences; The University of Manchester; Manchester; UK
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38
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Kornobis K, Kumar N, Lodowski P, Jaworska M, Piecuch P, Lutz JJ, Wong BM, Kozlowski PM. Electronic structure of the S1state in methylcobalamin: Insight from CASSCF/MC-XQDPT2, EOM-CCSD, and TD-DFT calculations. J Comput Chem 2013; 34:987-1004. [DOI: 10.1002/jcc.23204] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 10/25/2012] [Accepted: 11/19/2012] [Indexed: 11/12/2022]
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39
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Russell HJ, Jones AR, Hay S, Greetham GM, Towrie M, Scrutton NS. Protein Motions Are Coupled to the Reaction Chemistry in Coenzyme B 12-Dependent Ethanolamine Ammonia Lyase. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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40
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Russell HJ, Jones AR, Hay S, Greetham GM, Towrie M, Scrutton NS. Protein Motions Are Coupled to the Reaction Chemistry in Coenzyme B12-Dependent Ethanolamine Ammonia Lyase. Angew Chem Int Ed Engl 2012; 51:9306-10. [DOI: 10.1002/anie.201202502] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 07/13/2012] [Indexed: 11/12/2022]
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41
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Navizet I, Perry CB, Govender PP, Marques HM. cis Influence in Models of Cobalt Corrins by DFT and TD-DFT Studies. J Phys Chem B 2012; 116:8836-45. [DOI: 10.1021/jp304007a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Isabelle Navizet
- Molecular Sciences
Institute, School of Chemistry, University of Witwatersrand, P.O. Wits, Johannesburg, 2050 South
Africa
| | - Christopher B. Perry
- Molecular Sciences
Institute, School of Chemistry, University of Witwatersrand, P.O. Wits, Johannesburg, 2050 South
Africa
| | - Penny P. Govender
- Molecular Sciences
Institute, School of Chemistry, University of Witwatersrand, P.O. Wits, Johannesburg, 2050 South
Africa
- Department
of Applied
Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein, Johannesburg, 2028 South Africa
| | - Helder M. Marques
- Molecular Sciences
Institute, School of Chemistry, University of Witwatersrand, P.O. Wits, Johannesburg, 2050 South
Africa
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42
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Jones AR, Russell HJ, Greetham GM, Towrie M, Hay S, Scrutton NS. Ultrafast infrared spectral fingerprints of vitamin B12 and related cobalamins. J Phys Chem A 2012; 116:5586-94. [PMID: 22612868 DOI: 10.1021/jp304594d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Vitamin B(12) (cyanocobalamin, CNCbl) and its derivatives are structurally complex and functionally diverse biomolecules. The excited state and radical pair reaction dynamics that follow their photoexcitation have been previously studied in detail using UV-visible techniques. Similar time-resolved infrared (TRIR) data are limited, however. Herein we present TRIR difference spectra in the 1300-1700 cm(-1) region between 2 ps and 2 ns for adenosylcobalamin (AdoCbl), methylcobalamin (MeCbl), CNCbl, and hydroxocobalamin (OHCbl). The spectral profiles of all four cobalamins are complex, with broad similarities that suggest the vibrational excited states are related, but with a number of identifiable variations. The majority of the signals from AdoCbl and MeCbl decay with kinetics similar to those reported in the literature from UV-visible studies. However, there are regions of rapid (<10 ps) vibrational relaxation (peak shifts to higher frequencies from 1551, 1442, and 1337 cm(-1)) that are more pronounced in AdoCbl than in MeCbl. The AdoCbl data also exhibit more substantial changes in the amide I region and a number of more gradual peak shifts elsewhere (e.g., from 1549 to 1563 cm(-1)), which are not apparent in the MeCbl data. We attribute these differences to interactions between the bulky adenosyl and the corrin ring after photoexcitation and during radical pair recombination, respectively. Although spectrally similar to the initial excited state, the long-lived metal-to-ligand charge transfer state of MeCbl is clearly resolved in the kinetic analysis. The excited states of CNCbl and OHCbl relax to the ground state within 40 ps with few significant peak shifts, suggesting little or no homolysis of the bond between the Co and the upper axial ligand. Difference spectra from density functional theory calculations (where spectra from simplified cobalamins with an upper axial methyl were subtracted from those without) show qualitative agreement with the experimental data. They imply the excited state intermediates in the TRIR difference spectra resemble the dissociated states vibrationally (the cobalamin with the upper axial ligand missing) relative to the ground state with a methyl in this position. They also indicate that most of the TRIR signals arise from vibrations involving some degree of motion in the corrin ring. Such coupling of motions throughout the ring makes specific peak assignments neither trivial nor always meaningful, suggesting our data should be regarded as IR spectral fingerprints.
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Affiliation(s)
- Alex R Jones
- Manchester Interdisciplinary Biocentre and Faculty of Life Sciences, University of Manchester, UK
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43
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Bucher D, Sandala GM, Durbeej B, Radom L, Smith DM. The Elusive 5′-Deoxyadenosyl Radical in Coenzyme-B12-Mediated Reactions. J Am Chem Soc 2012; 134:1591-9. [DOI: 10.1021/ja207809b] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Denis Bucher
- School of Chemistry and ARC Centre of Excellence
for Free Radical Chemistry
and Biotechnology, University of Sydney, Sydney, NSW 2006, Australia
| | - Gregory M. Sandala
- School of Chemistry and ARC Centre of Excellence
for Free Radical Chemistry
and Biotechnology, University of Sydney, Sydney, NSW 2006, Australia
- Division of Organic
Chemistry and Biochemistry, Ruđer Bošković Institute, 10002 Zagreb, Croatia
| | - Bo Durbeej
- Division of Computational
Physics, IFM Theory and Modelling, Linköping University, SE-581 83 Linköping, Sweden
| | - Leo Radom
- School of Chemistry and ARC Centre of Excellence
for Free Radical Chemistry
and Biotechnology, University of Sydney, Sydney, NSW 2006, Australia
| | - David M. Smith
- Division of Organic
Chemistry and Biochemistry, Ruđer Bošković Institute, 10002 Zagreb, Croatia
- Computer-Chemie-Centrum, University of Erlangen-Nürnberg, 91052 Erlangen, Germany
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44
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Lodowski P, Jaworska M, Kornobis K, Andruniów T, Kozlowski PM. Electronic and Structural Properties of Low-lying Excited States of Vitamin B12. J Phys Chem B 2011; 115:13304-19. [DOI: 10.1021/jp200911y] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Piotr Lodowski
- Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland
| | - Maria Jaworska
- Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland
| | - Karina Kornobis
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Tadeusz Andruniów
- Institute of Physical and Theoretical Chemistry, Department of Chemistry, Wroclaw University of Technology, 50-370 Wroclaw, Poland
| | - Pawel M. Kozlowski
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
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45
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Jones AR, Hardman SJO, Hay S, Scrutton NS. Is There a Dynamic Protein Contribution to the Substrate Trigger in Coenzyme B12-Dependent Ethanolamine Ammonia Lyase? Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201105132] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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46
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Jones AR, Hardman SJO, Hay S, Scrutton NS. Is there a dynamic protein contribution to the substrate trigger in coenzyme B12-dependent ethanolamine ammonia lyase? Angew Chem Int Ed Engl 2011; 50:10843-6. [PMID: 21948289 DOI: 10.1002/anie.201105132] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Indexed: 11/07/2022]
Affiliation(s)
- Alex R Jones
- Faculty of Life Sciences, Photon Science Institute and Manchester Interdisciplinary Biocentre, University of Manchester, Manchester M1 7DN, UK
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47
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Robertson WD, Wang M, Warncke K. Characterization of protein contributions to cobalt-carbon bond cleavage catalysis in adenosylcobalamin-dependent ethanolamine ammonia-lyase by using photolysis in the ternary complex. J Am Chem Soc 2011; 133:6968-77. [PMID: 21491908 PMCID: PMC3092035 DOI: 10.1021/ja107052p] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein contributions to the substrate-triggered cleavage of the cobalt-carbon (Co-C) bond and formation of the cob(II)alamin-5'-deoxyadenosyl radical pair in the adenosylcobalamin (AdoCbl)-dependent ethanolamine ammonia-lyase (EAL) from Salmonella typhimurium have been studied by using pulsed-laser photolysis of AdoCbl in the EAL-AdoCbl-substrate ternary complex, and time-resolved probing of the photoproduct dynamics by using ultraviolet-visible absorption spectroscopy on the 10(-7)-10(-1) s time scale. Experiments were performed in a fluid dimethylsulfoxide/water cryosolvent system at 240 K, under conditions of kinetic competence for thermal cleavage of the Co-C bond in the ternary complex. The static ultraviolet-visible absorption spectra of holo-EAL and ternary complex are comparable, indicating that the binding of substrate does not labilize the cofactor cobalt-carbon (Co-C) bond by significantly distorting the equilibrium AdoCbl structure. Photolysis of AdoCbl in EAL at 240 K leads to cob(II)alamin-5'-deoxyadenosyl radical pair quantum yields of <0.01 at 10(-6) s in both holo-EAL and ternary complex. Three photoproduct states are populated following a saturating laser pulse, and labeled, P(f), P(s), and P(c). The relative amplitudes and first-order recombination rate constants of P(f) (0.4-0.6; 40-50 s(-1)), P(s) (0.3-0.4; 4 s(-1)), and P(c) (0.1-0.2; 0) are comparable in holo-EAL and in the ternary complex. Time-resolved, full-spectrum electron paramagnetic resonance (EPR) spectroscopy shows that visible irradiation alters neither the kinetics of thermal cob(II)alamin-substrate radical pair formation, nor the equilibrium between ternary complex and cob(II)alamin-substrate radical pair, at 246 K. The results indicate that substrate binding to holo-EAL does not "switch" the protein to a new structural state, which promptly stabilizes the cob(II)alamin-5'-deoxyadenosyl radical pair photoproduct, either through an increased barrier to recombination, a decreased barrier to further radical pair separation, or lowering of the radical pair state free energy, or a combination of these effects. Therefore, we conclude that such a change in protein structure, which is independent of changes in the AdoCbl structure, and specifically the Co-C bond length, is not a basis of Co-C bond cleavage catalysis. The results suggest that, following the substrate trigger, the protein interacts with the cofactor to contiguously guide the cleavage of the Co-C bond, at every step along the cleavage coordinate, starting from the equilibrium configuration of the ternary complex. The cleavage is thus represented by a diagonal trajectory across a free energy surface, that is defined by chemical (Co-C separation) and protein configuration coordinates.
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Affiliation(s)
| | - Miao Wang
- Department of Physics, Emory University, Atlanta, GA 30322
| | - Kurt Warncke
- Department of Physics, Emory University, Atlanta, GA 30322
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48
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Solheim H, Kornobis K, Ruud K, Kozlowski PM. Electronically Excited States of Vitamin B12 and Methylcobalamin: Theoretical Analysis of Absorption, CD, and MCD Data. J Phys Chem B 2010; 115:737-48. [DOI: 10.1021/jp109793r] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Harald Solheim
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, 9037 Tromsø, Norway, and Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Karina Kornobis
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, 9037 Tromsø, Norway, and Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Kenneth Ruud
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, 9037 Tromsø, Norway, and Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Pawel M. Kozlowski
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, 9037 Tromsø, Norway, and Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
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49
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Peng J, Tang KC, McLoughlin K, Yang Y, Forgach D, Sension RJ. Ultrafast Excited-State Dynamics and Photolysis in Base-Off B12 Coenzymes and Analogues: Absence of the trans-Nitrogenous Ligand Opens a Channel for Rapid Nonradiative Decay. J Phys Chem B 2010; 114:12398-405. [DOI: 10.1021/jp104641u] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Jian Peng
- Department of Chemistry and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Kuo-Chun Tang
- Department of Chemistry and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Kaitlin McLoughlin
- Department of Chemistry and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Yang Yang
- Department of Chemistry and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Danika Forgach
- Department of Chemistry and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Roseanne J. Sension
- Department of Chemistry and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1055
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50
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Jones AR, Woodward JR, Scrutton NS. Continuous wave photolysis magnetic field effect investigations with free and protein-bound alkylcobalamins. J Am Chem Soc 2010; 131:17246-53. [PMID: 19899795 DOI: 10.1021/ja9059238] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The activation of the Co-C bond in adenosylcobalamin-dependent enzymes generates a singlet-born Co(II)-adenosyl radical pair. Two of the salient questions regarding this process are: (1) What is the origin of the considerable homolysis rate enhancement achieved by this class of enzyme? (2) Are the reaction dynamics of the resultant radical pair sensitive to the application of external magnetic fields? Here, we present continuous wave photolysis magnetic field effect (MFE) data that reveal the ethanolamine ammonia lyase (EAL) active site to be an ideal microreactor in which to observe enhanced magnetic field sensitivity in the adenosylcobalamin radical pair. The observed field dependence is in excellent agreement with that calculated from published hyperfine couplings for the constituent radicals, and the magnitude of the MFE (<18%) is almost identical to that observed in a solvent containing 67% glycerol. Similar augmentation is not observed, however, in the equivalent experiments with EAL-bound methylcobalamin, where all field sensitivity observed in the free cofactor is washed out completely. Parallels are drawn between the latter case and the loss of field sensitivity in the EAL holoenzyme upon substrate binding (Jones et al. J. Am. Chem. Soc. 2007, 129, 15718-15727). Both are attributed to the rapid removal of the alkyl radical immediately after homolysis, such that there is inadequate radical pair recombination for the observation of field effects. Taken together, these results support the notion that rapid radical quenching, through the coupling of homolysis and hydrogen abstraction steps, and subsequent radical pair stabilization make a contribution to the observed rate acceleration of Co-C bond homolysis in adenosylcobalamin-dependent enzymes.
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Affiliation(s)
- Alex R Jones
- Manchester Interdisciplinary Biocentre and Faculty of Life Sciences, University of Manchester M1 7DN, United Kingdom
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