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Freindorf M, Delgado AAA, Kraka E. CO bonding in hexa‐ and pentacoordinate carboxy‐neuroglobin: A quantum mechanics/molecular mechanics and local vibrational mode study. J Comput Chem 2022. [DOI: 10.1002/jcc.26973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marek Freindorf
- Department of Chemistry Southern Methodist University Dallas Texas USA
| | | | - Elfi Kraka
- Department of Chemistry Southern Methodist University Dallas Texas USA
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2
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Matsumura H, Faponle AS, Hagedoorn PL, Tosha T, de Visser SP, Moënne-Loccoz P. Mechanism of substrate inhibition in cytochrome-c dependent NO reductases from denitrifying bacteria (cNORs). J Inorg Biochem 2022; 231:111781. [DOI: 10.1016/j.jinorgbio.2022.111781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 02/21/2022] [Accepted: 02/24/2022] [Indexed: 12/24/2022]
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3
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Amadei A, Aschi M. Stationary and Time-Dependent Carbon Monoxide Stretching Mode Features in Carboxy Myoglobin: A Theoretical-Computational Reappraisal. J Phys Chem B 2021; 125:13624-13634. [PMID: 34904432 DOI: 10.1021/acs.jpcb.1c05815] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The stationary and time-dependent infrared spectrum (IR) of the CO stretching mode (νCO) in carboxymyoglobin (MbCO), a longstanding problem of biophysical chemistry, has been modeled through a theoretical-computational method specifically designed for simulating quantum observables in complex atomic-molecular systems and based on a combined application of long time scale molecular dynamics simulations and quantum-chemical calculations. This study is basically focused on two aspects: (i) the origin of the stationary IR substates (termed as A0, A1, and A3) and (ii) the modeling and the interpretation of the νCO energy relaxation. The results, strengthened by a more than satisfactory agreement with the experimental data, concisely indicate that (i) the conformational His64-FeCO relevant substates, i.e., characterized by the formation-disruption of the H-bond between the above moieties, are the main responsible of the presence of two distinct and well separated (A0 and A1/A3) spectroscopic regions; (ii) the characteristic bimodal shape of the A1/A3 spectral region, according to our model, is the result of the fluctuation of the electric field pattern as provided by the protein-solvent framework perturbing the bound His64-CO-Heme complex; and (iii) the electric field pattern, in conjunction with the relatively high density of MbCO vibrational states, is also the main determinant of the νCO energy relaxation, characterizing its kinetic efficiency.
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Affiliation(s)
- Andrea Amadei
- Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma "Tor Vergata", via della Ricerca Scientifica 1, 00 133 Roma, Italia
| | - Massimiliano Aschi
- Dipartimento di Scienze Fisiche e Chimiche, Università de l'Aquila, via Vetoio (Coppito 1), 67 010 l'Aquila, Italia
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4
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Freindorf M, Kraka E. Critical assessment of the FeC and CO bond strength in carboxymyoglobin: a QM/MM local vibrational mode study. J Mol Model 2020; 26:281. [DOI: 10.1007/s00894-020-04519-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 08/26/2020] [Indexed: 12/15/2022]
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Osawa K, Kossowska D, Park K, Kwak K, Cho M. Two-dimensional infrared spectroscopic study of cytochrome c peroxidase activity in deep eutectic solvent. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:064703. [PMID: 31867407 PMCID: PMC6920052 DOI: 10.1063/1.5130940] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/04/2019] [Indexed: 06/10/2023]
Abstract
Deep eutectic solvents (DESs) prepared by mixing hydrogen-bond donor and acceptor molecules have been found to be of use in several applications. Recently, it was shown that DESs can enhance the peroxidation activity of cytochrome c. Here, to elucidate the effects of DESs on the peroxidase activity of cytochrome c, we carried out linear and nonlinear infrared spectroscopic studies of the CO stretch mode of carbon monoxide cytochrome c (COCytc) in ethylammonium chloride (EAC)/urea DES. The FTIR spectrum of COCytc shows a significant spectral shift upon addition of the DES. The broadening and red-shifting of the CO band are observed in both urea and DES solutions, which are induced by the change of the distal ligands around the heme. Although the FTIR study is sensitive to structural changes in the active site, it does not provide quantitative information about structural dynamics related to the catalytic activity itself. Thus, we carried out two-dimensional IR spectroscopy of the CO mode, which suggests that there is a different conformer that could be related to the enhanced catalytic activity in DES. In particular, the spectral diffusion dynamics of that conformer exhibits quite different behavior. The experimental results lead us to propose a hypothesis that the DES increases the population of the conformer with distal ligand lysines close to the reaction center through the combining effect of urea and EAC, which results in the enhancement of the peroxidase activity of cytochrome c. We anticipate that the present experimental work stimulates future investigations of the effects of DES on biocatalysis.
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Affiliation(s)
- Koji Osawa
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, South Korea
| | | | - Kwanghee Park
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, South Korea
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Li M, Oliver AG, Scheidt WR. Characterization of Metalloporphines: Iron(II) Carbonyls and Environmental Effects on νCO. Inorg Chem 2018; 57:5648-5656. [PMID: 29697973 DOI: 10.1021/acs.inorgchem.8b00599] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis and characterization of two new iron(II) porphine complexes is described. Porphine, the simplest porphyrin derivative, has been studied less than other synthetic porphyrins owing to synthetic difficulties and solubility issues. The subjects of this study are two six-coordinate iron(II) species further coordinated by CO and an imidazole ligand (either 1-methylimidazole or 2-methylimidazole). The two species have very different CO stretching frequencies, with the 2-methylimidazole complex having a very low stretching frequency of 1923 cm-1 compared to the more usual 1957 cm-1 for the 1-methylimidazole derivative. The very low frequency is the result of environmental effects; the oxygen atom of the carbonyl forms a hydrogen bond with an adjacent coordinated imidazole with a hydrogen atom from the N-H group. The two species, with their differing C-O stretches, also display substantial differences in the values of the Fe-C and C-O bond distances, as determined by their X-ray structures. The two bond distances are strongly correlated ( R = 0.98) in the direction expected for the classical π-backbonding model. The two bond distances are also strongly correlated with the C-O stretching frequencies. We can conclude that the Fe-C and C-O stretches are quite representative of the observed bond distances; their stretching frequencies are not affected by substantial mode mixing.
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Affiliation(s)
- Ming Li
- Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Allen G Oliver
- Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - W Robert Scheidt
- Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , Indiana 46556 , United States
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7
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Karain WI. Detecting transitions in protein dynamics using a recurrence quantification analysis based bootstrap method. BMC Bioinformatics 2017; 18:525. [PMID: 29179670 PMCID: PMC5704401 DOI: 10.1186/s12859-017-1943-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/15/2017] [Indexed: 11/17/2022] Open
Abstract
Background Proteins undergo conformational transitions over different time scales. These transitions are closely intertwined with the protein’s function. Numerous standard techniques such as principal component analysis are used to detect these transitions in molecular dynamics simulations. In this work, we add a new method that has the ability to detect transitions in dynamics based on the recurrences in the dynamical system. It combines bootstrapping and recurrence quantification analysis. We start from the assumption that a protein has a “baseline” recurrence structure over a given period of time. Any statistically significant deviation from this recurrence structure, as inferred from complexity measures provided by recurrence quantification analysis, is considered a transition in the dynamics of the protein. Results We apply this technique to a 132 ns long molecular dynamics simulation of the β-Lactamase Inhibitory Protein BLIP. We are able to detect conformational transitions in the nanosecond range in the recurrence dynamics of the BLIP protein during the simulation. The results compare favorably to those extracted using the principal component analysis technique. Conclusions The recurrence quantification analysis based bootstrap technique is able to detect transitions between different dynamics states for a protein over different time scales. It is not limited to linear dynamics regimes, and can be generalized to any time scale. It also has the potential to be used to cluster frames in molecular dynamics trajectories according to the nature of their recurrence dynamics. One shortcoming for this method is the need to have large enough time windows to insure good statistical quality for the recurrence complexity measures needed to detect the transitions.
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Affiliation(s)
- Wael I Karain
- Department of Physics, Birzeit University, P.O.Box 14, Birzeit, Palestine.
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Mirmohades M, Adamska-Venkatesh A, Sommer C, Reijerse E, Lomoth R, Lubitz W, Hammarström L. Following [FeFe] Hydrogenase Active Site Intermediates by Time-Resolved Mid-IR Spectroscopy. J Phys Chem Lett 2016; 7:3290-3293. [PMID: 27494400 DOI: 10.1021/acs.jpclett.6b01316] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Time-resolved nanosecond mid-infrared spectroscopy is for the first time employed to study the [FeFe] hydrogenase from Chlamydomonas reinhardtii and to investigate relevant intermediates of the enzyme active site. An actinic 355 nm, 10 ns laser flash triggered photodissociation of a carbonyl group from the CO-inhibited state Hox-CO to form the state Hox, which is an intermediate of the catalytic proton reduction cycle. Time-resolved infrared spectroscopy allowed us to directly follow the subsequent rebinding of the carbonyl, re-forming Hox-CO, and determine the reaction half-life to be t1/2 ≈ 13 ± 5 ms at room temperature. This gives direct information on the dynamics of CO inhibition of the enzyme.
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Affiliation(s)
- Mohammad Mirmohades
- Department of Chemistry - Ångström Laboratory, Uppsala University , Box 523, 751 20 Uppsala, Sweden
| | - Agnieszka Adamska-Venkatesh
- Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Constanze Sommer
- Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Edward Reijerse
- Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Reiner Lomoth
- Department of Chemistry - Ångström Laboratory, Uppsala University , Box 523, 751 20 Uppsala, Sweden
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Leif Hammarström
- Department of Chemistry - Ångström Laboratory, Uppsala University , Box 523, 751 20 Uppsala, Sweden
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Lee T, Kim J, Park J, Pak Y, Kim H, Lim M. Rebinding dynamics of NO to microperoxidase-8 probed by time-resolved vibrational spectroscopy. Phys Chem Chem Phys 2016; 18:5192-202. [PMID: 26813691 DOI: 10.1039/c5cp06336a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Femtosecond vibrational spectroscopy was used to probe the rebinding kinetics of NO to microperoxidase-8 (Mp), an ideal model system for the active site of ligand-binding heme proteins, including myoglobin and hemoglobin, after the photodeligation of MpNO in glycerol/water (G/W) solutions at 294 K. The geminate rebinding (GR) of NO to Mp in viscous solutions was highly efficient and ultrafast and negligibly dependent on the solution viscosity, which was adjusted by changing the glycerol content from 65% to 90% by volume in G/W mixtures. The kinetics of the GR of NO to Mp in viscous solutions was well represented by an exponential function with a time constant of ca. 11 ps. Although the kinetic traces of the GR of NO to Mp in solutions with three different viscosities (18, 81, and 252 cP) almost overlap, they show a slight difference early in the decay process. The kinetic traces were also described by the diffusion-controlled reaction theory with a Coulomb potential. Since the ligand is deligated in a neutral form, an ionic pair of NO(-) and Mp(+) may be produced before forming the Mp-NO bond by an electron transfer from Mp to NO as the deligated NO is sufficiently near to the Fe atom of Mp. The strong reactivity between NO and ferrous heme may arise from the Coulomb interaction between the reacting pair, which is consistent with the harpooning mechanism for NO binding to heme.
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Affiliation(s)
- Taegon Lee
- Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University, Busan, 46241 Korea.
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Lima FA, Penfold TJ, van der Veen RM, Reinhard M, Abela R, Tavernelli I, Rothlisberger U, Benfatto M, Milne CJ, Chergui M. Probing the electronic and geometric structure of ferric and ferrous myoglobins in physiological solutions by Fe K-edge absorption spectroscopy. Phys Chem Chem Phys 2014; 16:1617-31. [PMID: 24317683 DOI: 10.1039/c3cp53683a] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present an iron K-edge X-ray absorption study of carboxymyoglobin (MbCO), nitrosylmyoglobin (MbNO), oxymyoglobin (MbO2), cyanomyoglobin (MbCN), aquomet myoglobin (metMb) and unligated myoglobin (deoxyMb) in physiological media. The analysis of the XANES region is performed using the full-multiple scattering formalism, implemented within the MXAN package. This reveals trends within the heme structure, absent from previous crystallographic and X-ray absorption analysis. In particular, the iron-nitrogen bond lengths in the porphyrin ring converge to a common value of about 2 Å, except for deoxyMb whose bigger value is due to the doming of the heme. The trends of the Fe-Nε (His93) bond length is found to be consistent with the effect of ligand binding to the iron, with the exception of MbNO, which is explained in terms of the repulsive trans effect. We derive a high resolution description of the relative geometry of the ligands with respect to the heme and quantify the magnitude of the heme doming in the deoxyMb form. Finally, time-dependent density functional theory is used to simulate the pre-edge spectra and is found to be in good agreement with the experiment. The XAS spectra typically exhibit one pre-edge feature which arises from transitions into the unoccupied dσ and dπ - πligand* orbitals. 1s → dπ transitions contribute weakly for MbO2, metMb and deoxyMb. However, despite this strong Fe d contribution these transitions are found to be dominated by the dipole (1s → 4p) moment due to the low symmetry of the heme environment.
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Affiliation(s)
- Frederico A Lima
- École Polytechnique Fédérale de Lausanne, Laboratoire de Spectroscopie Ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne, CH, Switzerland.
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Park S, Park J, Lin HW, Lim M. Vibrational Relaxation of Cyanate or Thiocyanate Bound to Ferric Heme Proteins Studied by Femtosecond Infrared Spectroscopy. B KOREAN CHEM SOC 2014. [DOI: 10.5012/bkcs.2014.35.3.758] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Choi JH, Kwak KW, Cho M. Computational infrared and two-dimensional infrared photon echo spectroscopy of both wild-type and double mutant myoglobin-CO proteins. J Phys Chem B 2013; 117:15462-78. [PMID: 23869523 DOI: 10.1021/jp405210s] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The CO stretching mode of both wild-type and double mutant ( T67R / S92D ) MbCO (carbonmonoxymyoglobin) proteins is an ideal infrared (IR) probe for studying the local electrostatic environment inside the myoglobin heme pocket. Recently, to elucidate the conformational switching dynamics between two distinguishable states, extensive IR absorption, IR pump-probe, and two-dimensional (2D) IR spectroscopic studies for various mutant MbCO's have been performed by the Fayer group. They showed that the 2D IR spectroscopy of the double mutant, which has a peroxidase enzyme activity, reveals a rapid chemical exchange between two distinct states, whereas that of the wild-type does not. Despite the fact that a few simulation studies on these systems were already performed and reported, such complicated experimental results have not been fully reproduced nor described in terms of conformational state-to-state transition processes. Here, we first develop a distributed vibrational solvatochromic charge model for describing the CO stretch frequency shift reflecting local electric potential changes. Then, by carrying out molecular dynamic simulations of the two MbCO's and examining their CO frequency trajectories, it becomes possible to identify a proper reaction coordinate consisting of His64 imidazole ring rotation and its distance to the CO ligand. From the 2D surfaces of the resulting potential of mean forces, the spectroscopically distinguished A1 and A3 states of the wild-type as well as two more substates of the double mutant are identified and their vibrational frequencies and distributions are separately examined. Our simulated IR absorption and 2D IR spectra of the two MbCO's are directly compared with the previous experimental results reported by the Fayer group. The chemical exchange rate constants extracted from the two-state kinetic analyses of the simulated 2D IR spectra are in excellent agreement with the experimental values. On the basis of the quantitative agreement between the simulated spectra and experimental ones, we further examine the conformational differences in the heme pockets of the two proteins and show that the double mutation, T67R / S92D , suppresses the A1 population, restricts the imidazole ring rotation, and increases hydrogen-bond strength between the imidazole Nε-H and the oxygen atom of the CO ligand. It is believed that such delicate change of distal His64 imidazole ring dynamics induced by the double mutation may be responsible for its enhanced peroxidase catalytic activity as compared to the wild-type myoglobin.
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Affiliation(s)
- Jun-Ho Choi
- Department of Chemistry, Korea University , Seoul 136-713, Korea
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Park J, Lee T, Lim M. Vibrational relaxation of NO stretching modes in ferrous NO and ferric NO in model heme. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.09.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Kim J, Park J, Lee T, Pak Y, Lim M. Dynamics of geminate rebinding of CO to cytochrome c in guanidine HCl probed by femtosecond vibrational spectroscopy. J Phys Chem B 2013; 117:4934-44. [PMID: 23590118 DOI: 10.1021/jp401481q] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Femtosecond vibrational spectroscopy was used to probe the rebinding dynamics of CO to cytochrome c (Cytc) in 1.8 and 7 M guanidine HCl (GdnHCl) after photodeligation of the corresponding CO-bound protein in D2O buffer (pD = 7.4) at 283 K. Geminate rebinding (GR) dynamics of CO to the folded Cytc in 1.8 M GdnHCl (nCytc) is similar to that to chemically modified cytochrome c (cCytc), suggesting that the overall conformations of nCytcCO and cCytcCO are similar. About 86% of the dissociated CO molecules were geminately rebound to nCytc nonexponentially within 1 ns. The efficient GR of CO to the folded Cytc can be attributed to the organized protein matrix near the active site of nCytc that provides an efficient trap for the diffusing CO ligand after photodissociation. Although the concentration of nCytc did not affect its GR yield of CO, GR yield of CO to the unfolded Cytc in 7 M GdnHCl (uCytc) increased from 5 to 30% as the protein concentration increased from 0.3 to 9 mM. Time-resolved spectra of the (13)CO dissociated from both 9 mM nCytc(13)CO and 9 mM uCytc(13)CO showed a growing band with a peak at 2090 cm(-1) on the picosecond time scale, which was assigned to (13)CO in D2O solvent. At 1 ns, the fraction of the CO band in the solvent was about 10% of the nascent photodeligated protein in nCytc and more than 50% in the concentrated uCytc. Whereas a small opening in the active site of nCytc is responsible for the ultrafast escape of CO to solution in the folded protein, a large fraction of the CO escape to the solvent in uCytc results from the denatured structure of the active site in the unfolded protein. The spectrum of the CO dissociated from the concentrated uCytcCO contained a band that decayed as efficiently as that for the folded protein, suggesting that some fraction of uCytcCO might form aggregates even in 7 M denaturant, such that the aggregate acts as an efficient trap for the diffusing CO after deligation. No hint of precipitate in the concentrated uCytcCO and protein refolding upon dilution of the GdnHCl indicate that the aggregate does not grow continuously but remains as a soluble oligomer. The delayed appearance of the solvated CO and the inefficient GR of CO in uCytcCO suggest that the monomeric unfolded CytcCO so loosely arranged that the protein matrix cannot trap CO efficiently but the bound CO is still buried within hydrophobic residues even under the harsh denaturation condition.
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Affiliation(s)
- Jooyoung Kim
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan, 609-735 Korea
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Park J, Lee T, Lim M. Geminate rebinding dynamics of nitric oxide to ferric hemoglobin in D2O solution. Photochem Photobiol Sci 2013; 12:1008-15. [PMID: 23512239 DOI: 10.1039/c3pp50014d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Femtosecond mid-infrared (mid-IR) spectroscopy was used to probe geminate rebinding (GR) dynamics of photo-released nitric oxide (NO) to ferric hemoglobin (Hb(III)) in D2O solution at room temperature. Time-resolved vibrational spectra exhibit two overlapping NO bands for NO-bound Hb(III) (Hb(III)NO), a major band at 1925 cm(-1) (89%) and a minor one at 1905 cm(-1) (11%), suggesting that Hb(III)NO has at least two conformational substates. Both bands decay nonexponentially, each with a different time scale, and the decays are described by a stretched exponential function; the major band's decay is described by 0.96 exp(-t/40 ps)(0.86) + 0.04 and the minor band's decay is described by exp(-t/85 ps)(0.75). These decays arise mainly from the GR of the photo-released NO to Hb(III), indicating that the bound state's conformer influences the NO binding. In particular, the His64 residue, known to have inward conformation in the major band and outward conformation in the minor band, plays a significant role in controlling the binding of NO to Hb(III). The GR of NO to ferric Hb is slower than that to ferrous Hb, which shows fast and efficient GR due to the high reactivity of NO to the heme Fe(ii). The slower GR of NO to Hb(III) may be caused by the lower reactivity of NO to the heme Fe(iii).
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Affiliation(s)
- Jaeheung Park
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea
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Nienhaus K, Nienhaus GU. A spectroscopic study of structural heterogeneity and carbon monoxide binding in neuroglobin. J Biol Phys 2013; 31:417-32. [PMID: 23345908 DOI: 10.1007/s10867-005-0173-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Neuroglobin (Ngb) is a small globular protein that binds diatomic ligands like oxygen, carbon monoxide (CO) and nitric oxide at a heme prosthetic group. We have performed FTIR spectroscopy in the infrared stretching bands of CO and flash photolysis with monitoring in the electronic heme absorption bands to investigate structural heterogeneity at the active site of Ngb and its effects on CO binding and migration at cryogenic temperatures. Four CO stretching bands were identified; they correspond to discrete conformations that differ in structural details and CO binding properties. Based on a comparison of bound-state and photoproduct IR spectra of the wild-type protein, Ngb distal pocket mutants and myoglobin, we have provided structural interpretations of the conformations associated with the different CO bands. We have also studied ligand migration to the primary docking site, B. Rebinding from this site is governed by very low enthalpy barriers (∼1 kJ/mol), indicating an extremely reactive heme iron. Moreover, we have observed ligand migration to a secondary docking site, C, from which CO rebinding involves higher enthalpy barriers.
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Affiliation(s)
- Karin Nienhaus
- Department of Biophysics, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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Yan L, Pelmenschikov V, Dapper CH, Scott AD, Newton WE, Cramer SP. IR-monitored photolysis of CO-inhibited nitrogenase: a major EPR-silent species with coupled terminal CO ligands. Chemistry 2012; 18:16349-57. [PMID: 23136072 PMCID: PMC4497518 DOI: 10.1002/chem.201202072] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 08/22/2012] [Indexed: 11/07/2022]
Abstract
Fourier transform infrared spectroscopy (FTIR) was used to observe the photolysis and recombination of a new EPR-silent CO-inhibited form of α-H195Q nitrogenase from Azotobacter vinelandii. Photolysis at 4 K reveals a strong negative IR difference band at nu = 1938 cm(-1), along with a weaker negative feature at 1911 cm(-1). These bands and the associated chemical species have both been assigned the label "Hi-3". A positive band at nu = 1921 cm(-1) was assigned to the "Lo-3" photoproduct. By using an isotopic mixture of (12)C (16)O and (13)C (18)O, we show that the Hi-3 bands arise from coupling of two similar CO oscillators with one uncoupled frequency at approximately nu = 1917 cm(-1). Although in previous studies Lo-3 was not observed to recombine, by extending the observation range to 200-240 K, we found that recombination to Hi-3 does indeed occur, with an activation energy of approximately 6.5 kJ mol(-1). The frequencies of the Hi-3 bands suggest terminal CO ligation. This hypothesis was tested with DFT calculations on models with terminal CO ligands on Fe2 and Fe6 of the FeMo-cofactor. An S = 0 model with both CO ligands in exo positions predicts symmetric and asymmetric stretches at nu = 1938 and 1909 cm(-1), respectively, with relative band intensities of about 3.5:1, which is in good agreement with experiment. From the observed IR intensities, Hi-3 was found to be present at a concentration about equal to that of the EPR-active Hi-1 species. The relevance of Hi-3 to the nitrogenase catalytic mechanism and its recently discovered Fischer-Tropsch chemistry is discussed.
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Affiliation(s)
- Lifen Yan
- Department of Chemistry, University of California, Davis, CA 95616
| | | | - Christie H. Dapper
- Department of Biochemistry, Virginia Polytechnic Institute, Blacksburg, VA 24061, USA
| | - Aubrey D. Scott
- Department of Chemistry, University of California, Davis, CA 95616
| | - William E. Newton
- Department of Biochemistry, Virginia Polytechnic Institute, Blacksburg, VA 24061, USA
| | - Stephen P. Cramer
- Department of Chemistry, University of California, Davis, CA 95616
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA 94720
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Thielges MC, Fayer MD. Protein dynamics studied with ultrafast two-dimensional infrared vibrational echo spectroscopy. Acc Chem Res 2012; 45:1866-74. [PMID: 22433178 DOI: 10.1021/ar200275k] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Proteins, enzymes, and other biological molecules undergo structural dynamics as an intrinsic part of their biological functions. While many biological processes occur on the millisecond, second, and even longer time scales, the fundamental structural dynamics that eventually give rise to such processes occur on much faster time scales. Many decades ago, chemical kineticists focused on the inverse of the reaction rate constant as the important time scale for a chemical reaction. However, through transition state theory and a vast amount of experimental evidence, we now know that the key events in a chemical reaction can involve structural fluctuations that take a system of reactants to its transition state, the crossing of a barrier, and the eventual relaxation to product states. Such dynamics occur on very fast time scales. Today researchers would like to investigate the fast structural fluctuations of biological molecules to gain an understanding of how biological processes proceed from simple structural changes in biomolecules to the final, complex biological function. The study of the fast structural dynamics of biological molecules requires experiments that operate on the appropriate time scales, and in this Account, we discuss the application of ultrafast two-dimensional infrared (2D IR) vibrational echo spectroscopy to the study of protein dynamics. The 2D IR vibrational echo experiment is akin to 2D NMR, but it operates on time scales many orders of magnitude faster. In the experiments, a particular vibrational oscillator serves as a vibrational dynamics probe. As the structure of the protein evolves in time, the structural changes are manifested as time-dependent changes in the frequency of the vibrational dynamics probe. The 2D IR vibrational echo experiments can track the vibrational frequency evolution, which we then relate to the time evolution of the protein structure. In particular, we measured protein substate interconversion for mutants of myoglobin using 2D IR chemical exchange spectroscopy and observed well-defined substate interconversion on a sub-100 ps time scale. In another study, we investigated the influence of binding five different substrates to the enzyme cytochrome P450(cam). The various substrates affect the enzyme dynamics differently, and the observed dynamics are correlated with the enzyme's selectivity of hydroxylation of the substrates and with the substrate binding affinity.
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Affiliation(s)
- Megan C. Thielges
- Department of Chemistry Stanford University, Stanford, California 94305, United States
| | - Michael D. Fayer
- Department of Chemistry Stanford University, Stanford, California 94305, United States
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21
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Kim J, Park J, Lee T, Lim M. Dynamics of Geminate Rebinding of NO with Cytochrome c in Aqueous Solution Using Femtosecond Vibrational Spectroscopy. J Phys Chem B 2012; 116:13663-71. [PMID: 23113639 DOI: 10.1021/jp308468j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Jooyoung Kim
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735,
Korea
| | - Jaeheung Park
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735,
Korea
| | - Taegon Lee
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735,
Korea
| | - Manho Lim
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735,
Korea
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22
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King JT, Kubarych KJ. Site-specific coupling of hydration water and protein flexibility studied in solution with ultrafast 2D-IR spectroscopy. J Am Chem Soc 2012; 134:18705-12. [PMID: 23101613 DOI: 10.1021/ja307401r] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
There is considerable evidence for the slaving of biomolecular dynamics to the motions of the surrounding solvent environment, but to date there have been few direct experimental measurements capable of site-selectively probing both the dynamics of the water and the protein with ultrafast time resolution. Here, two-dimensional infrared spectroscopy (2D-IR) is used to study the ultrafast hydration and protein dynamics sensed by a metal carbonyl vibrational probe covalently attached to the surface of hen egg white lysozyme dissolved in D(2)O/glycerol solutions. Surface labeling provides direct access to the dynamics at the protein-water interface, where both the hydration and the protein dynamics can be observed simultaneously through the vibrational probe's frequency-frequency correlation function. In pure D(2)O, the correlation function shows a fast initial 3 ps decay corresponding to fluctuations of the hydration water, followed by a significant static offset attributed to fluctuations of the protein that are not sampled within the <20 ps experimental window. Adding glycerol increases the bulk solvent viscosity while leaving the protein structurally intact and hydrated. The hydration dynamics exhibit a greater than 3-fold slowdown between 0 and 80% glycerol (v/v), and the contribution from the protein's dynamics is found to slow in a nearly identical fashion. In addition, the magnitude of the dynamic slowdown associated with hydrophobic hydration is directly measured and shows quantitative agreement with predictions from molecular dynamics simulations.
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Affiliation(s)
- John T King
- Department of Chemistry, University of Michigan, Ann Arbor, 48109, United States
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23
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Kim S, Park J, Lee T, Lim M. Direct Observation of Ligand Rebinding Pathways in Hemoglobin Using Femtosecond Mid-IR Spectroscopy. J Phys Chem B 2012; 116:6346-55. [PMID: 22587393 DOI: 10.1021/jp3026495] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Seongheun Kim
- Department of Chemistry and Chemistry
Institute for
Functional Materials, Pusan National University, Busan 609-735, Korea
| | - Jaeheung Park
- Department of Chemistry and Chemistry
Institute for
Functional Materials, Pusan National University, Busan 609-735, Korea
| | - Taegon Lee
- Department of Chemistry and Chemistry
Institute for
Functional Materials, Pusan National University, Busan 609-735, Korea
| | - Manho Lim
- Department of Chemistry and Chemistry
Institute for
Functional Materials, Pusan National University, Busan 609-735, Korea
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24
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Kim S, Lim M. Protein Conformation-Controlled Rebinding Barrier of NO and Its Binding Trajectories in Myoglobin and Hemoglobin at Room Temperature. J Phys Chem B 2012; 116:5819-30. [DOI: 10.1021/jp300176q] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Seongheun Kim
- Department of Chemistry and Chemistry Institute for
Functional Materials, Pusan National University, Busan 609-735, Korea
| | - Manho Lim
- Department of Chemistry and Chemistry Institute for
Functional Materials, Pusan National University, Busan 609-735, Korea
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25
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Schweitzer-Stenner R. Using spectroscopic tools to probe porphyrin deformation and porphyrin-protein interactions. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424611003343] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The reactivity and functionality of heme proteins are to a significant extent determined by the conformation of their functional heme groups and by the interaction of axial ligands with their protein environment. This review focuses on experimental methods and theoretical concepts for elucidating symmetry lowering perturbations of the heme induced by the protein environment of the heme pocket. First, we discuss a variety of methods which can be used to probe the electric field at the heme, including spectral hole burning as well as low temperature absorption and room temperature circular dichroism spectroscopy. Second, we show how heme deformations can be described as superposition of deformations along normal coordinates, thereby using the irreducible representations of the D4h point group as a classification tool. Finally, resonance Raman spectroscopy is introduced as a tool to probe the deformations of metalloprophyrins in solution and in protein matrices by measuring and comparing intensities and depolarization properties rather than wavenumber positions.
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26
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Cazade PA, Huang J, Yosa J, Szymczak JJ, Meuwly M. Atomistic simulations of reactive processes in the gas- and condensed-phase. INT REV PHYS CHEM 2012. [DOI: 10.1080/0144235x.2012.694694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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27
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Farah K, Müller-Plathe F, Böhm MC. Classical Reactive Molecular Dynamics Implementations: State of the Art. Chemphyschem 2012; 13:1127-51. [DOI: 10.1002/cphc.201100681] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Indexed: 11/09/2022]
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28
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Adamczyk K, Candelaresi M, Kania R, Robb K, Bellota-Antón C, Greetham GM, Pollard MR, Towrie M, Parker AW, Hoskisson PA, Tucker NP, Hunt NT. The effect of point mutation on the equilibrium structural fluctuations of ferric Myoglobin. Phys Chem Chem Phys 2012; 14:7411-9. [DOI: 10.1039/c2cp23568d] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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29
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Bianconi A, Ciasca G, Tenenbaum A, Battisti A, Campi G. Temperature and solvent dependence of the dynamical landscape of tau protein conformations. J Biol Phys 2012; 38:169-79. [PMID: 23277677 PMCID: PMC3285732 DOI: 10.1007/s10867-011-9244-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 10/18/2011] [Indexed: 02/05/2023] Open
Abstract
We report the variation with temperature of the ensemble distribution of conformations spanned by the tau protein in its dynamical states measured by small-angle X-ray scattering (SAXS) using synchrotron radiation. The SAXS data show a clear temperature variation of the distribution of occupied protein conformations from 293 to 318 K. More conformations with a smaller radius of gyration are occupied at higher temperature. The protein-solvent interactions are shown by computer simulation to be essential for controlling the dynamics of protein conformations, providing evidence for the key role of water solvent in the protein dynamics, as proposed by Giorgio Careri.
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Affiliation(s)
- Antonio Bianconi
- Physics Department, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Roma, Italy
| | - Gabriele Ciasca
- Physics Department, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Roma, Italy
| | - Alexander Tenenbaum
- Physics Department, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Roma, Italy
| | - Anna Battisti
- Physics Department, University of Trento, Via Sommarive 14, 38123 Povo (Trento), Italy
- LISC, FBK-CMM and University of Trento, Via Sommarive 18, 38123 Povo (Trento), Italy
| | - Gaetano Campi
- CNR, Institute of Crystallography, Via Salaria Km 29.300, 00016 Monterotondo (Roma), Italy
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30
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Healy AJ, Reeve HA, Vincent KA. Development of an infrared spectroscopic approach for studying metalloenzyme active site chemistry under direct electrochemical control. Faraday Discuss 2011; 148:345-57; discussion 421-41. [DOI: 10.1039/c004274a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Lutz S, Meuwly M. Structural characterization of spectroscopic substates in carbonmonoxy neuroglobin. Faraday Discuss 2011; 150:375-90; discussion 391-418. [DOI: 10.1039/c0fd00003e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Bagchi S, Nebgen BT, Loring RF, Fayer MD. Dynamics of a myoglobin mutant enzyme: 2D IR vibrational echo experiments and simulations. J Am Chem Soc 2010; 132:18367-76. [PMID: 21142083 PMCID: PMC3033732 DOI: 10.1021/ja108491t] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Myoglobin (Mb) double mutant T67R/S92D displays peroxidase enzymatic activity in contrast to the wild type protein. The CO adduct of T67R/S92D shows two CO absorption bands corresponding to the A(1) and A(3) substates. The equilibrium protein dynamics for the two distinct substates of the Mb double mutant are investigated by using two-dimensional infrared (2D IR) vibrational echo spectroscopy and molecular dynamics (MD) simulations. The time-dependent changes in the 2D IR vibrational echo line shapes for both of the substates are analyzed using the center line slope (CLS) method to obtain the frequency-frequency correlation function (FFCF). The results for the double mutant are compared to those from the wild type Mb. The experimentally determined FFCF is compared to the FFCF obtained from molecular dynamics simulations, thereby testing the capacity of a force field to determine the amplitudes and time scales of protein structural fluctuations on fast time scales. The results provide insights into the nature of the energy landscape around the free energy minimum of the folded protein structure.
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Affiliation(s)
- Sayan Bagchi
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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33
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Kim JY, Park JH, Chowdhury SA, Lim MH. Picosecond Dynamics of CN--Ligated Ferric Cytochrome c after Photoexcitation Using Time-resolved Vibrational Spectroscopy. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.12.3771] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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34
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35
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Servantie J, Atilgan C, Atilgan AR. Depth dependent dynamics in the hydration shell of a protein. J Chem Phys 2010; 133:085101. [DOI: 10.1063/1.3481089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Park J, Lee T, Lim M. Viscosity-Dependent Dynamics of CO Rebinding to Microperoxidase-8 in Glycerol/Water Solution. J Phys Chem B 2010; 114:10897-904. [DOI: 10.1021/jp1050436] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Jaeheung Park
- Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University, Busan, 609-735 Korea
| | - Taegon Lee
- Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University, Busan, 609-735 Korea
| | - Manho Lim
- Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University, Busan, 609-735 Korea
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37
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Nienhaus K, Nienhaus GU. Ligand dynamics in heme proteins observed by Fourier transform infrared-temperature derivative spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:1030-41. [PMID: 20656073 DOI: 10.1016/j.bbapap.2010.07.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 07/14/2010] [Accepted: 07/15/2010] [Indexed: 11/29/2022]
Abstract
Fourier transform infrared (FTIR) spectroscopy is a powerful tool for the investigation of protein-ligand interactions in heme proteins. Nitric oxide and carbon monoxide are attractive physiologically relevant ligands because their bond stretching vibrations give rise to strong mid-infrared absorption bands that can be measured with exquisite sensitivity and precision using photolysis difference spectroscopy at cryogenic temperatures. These stretching bands are fine-tuned by electrostatic interactions with the environment and, therefore, ligands can be utilized as local probes of structure and dynamics. Bound to the heme iron, the ligand stretching bands are susceptible to changes in the iron-ligand bond and the electric field at the active site. Upon photolysis, the vibrational bands display changes due to ligand relocation to docking sites within the protein, rotational motions of the ligand in these sites and protein conformational changes. Photolysis difference spectra taken over a wide temperature range (3-300K) using specific temperature protocols for sample photodissociation can provide detailed insights into both protein and ligand dynamics. Moreover, temperature-derivative spectroscopy (TDS) has proven to be a particularly powerful technique to study protein-ligand interactions. The FTIR-TDS technique has been extensively applied to studies of carbon monoxide binding to heme proteins, whereas measurements with nitric oxide are still scarce. Here we describe infrared cryo-spectroscopy and present a variety of applications to the study of protein-ligand interactions in heme proteins. This article is part of a Special Issue entitled: Protein Dynamics: Experimental and Computational Approaches.
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Affiliation(s)
- Karin Nienhaus
- Karlsruhe Institute of Technology (KIT), Institute of Applied Physics and Center for Functional Nanostructures, Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe, Germany
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38
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39
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Murphy EJ, Maréchal A, Segal AW, Rich PR. CO binding and ligand discrimination in human myeloperoxidase. Biochemistry 2010; 49:2150-8. [PMID: 20146436 DOI: 10.1021/bi9021507] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Despite the fact that ferrous myeloperoxidase (MPO) can bind both O(2) and NO, its ability to bind CO has been questioned. UV/visible spectroscopy was used to confirm that CO induces small spectral shifts in ferrous MPO, and Fourier transform infrared difference spectroscopy showed definitively that these arose from formation of a heme ferrous-CO compound. Recombination rates after CO photolysis were monitored at 618 and 645 nm as a function of CO concentration and pH. At pH 6.3, k(on) and k(off) were 0.14 mM(-1) x s(-1) and 0.23 s(-1), respectively, yielding an unusually high K(D) of 1.6 mM. This affinity of MPO for CO is 10 times weaker than its affinity for O(2). The observed rate constant for CO binding increased with increasing pH and was governed by a single protonatable group with a pK(a) of 7.8. Fourier transform infrared spectroscopy revealed two different conformations of bound CO with frequencies at 1927 and 1942 cm(-1). Their recombination rate constants were identical, indicative of two forms of bound CO that are in rapid thermal equilibrium rather than two distinct protein populations with different binding sites. The ratio of bound states was pH-dependent (pK(a) approximately 7.4) with the 1927 cm(-1) form favored at high pH. Structural factors that account for the ligand-binding properties of MPO are identified by comparisons with published data on a range of other ligand-binding heme proteins, and support is given to the recent suggestion that the proximal His336 in MPO is in a true imidazolate state.
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Affiliation(s)
- Emma J Murphy
- Centre for Molecular Medicine, Division of Medicine, University College London, 5 University Street, London WC1E 6JJ, UK
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40
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Devereux M, Meuwly M. Force Field Optimization using Dynamics and Ensemble Averaged Data: Vibrational Spectra and Relaxation in Bound MbCO. J Chem Inf Model 2010; 50:349-57. [DOI: 10.1021/ci9004404] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Michael Devereux
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
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41
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Tomita A, Sato T, Nozawa S, Koshihara SY, Adachi SI. Tracking ligand-migration pathways of carbonmonoxy myoglobin in crystals at cryogenic temperatures. Acta Crystallogr A 2010; 66:220-8. [DOI: 10.1107/s0108767309050752] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 11/25/2009] [Indexed: 05/26/2023] Open
Abstract
In order to explore the ligand-migration dynamics in myoglobin induced by photodissociation, cryogenic X-ray crystallographic investigations of carbonmonoxy myoglobin crystals illuminated by continuous wave and pulsed lasers at 1–15 kHz repetition rate have been carried out. Here it is shown that this novel method, extended pulsed-laser pumping of carbonmonoxy myoglobin, promotes ligand migration in the protein matrix by crossing the glass transition temperature repeatedly, and enables the visualization of the migration pathway of the photodissociated ligands in native Mb at cryogenic temperatures. It has revealed that the migration of the CO molecule into each cavity induces structural changes of the amino-acid residues around the cavity which result in the expansion of the cavity. The sequential motion of the ligand and the cavity suggests a self-opening mechanism of the ligand-migration channel arising by induced fit.
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42
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Devereux M, Plattner N, Meuwly M. Application of multipolar charge models and molecular dynamics simulations to study stark shifts in inhomogeneous electric fields. J Phys Chem A 2010; 113:13199-209. [PMID: 19681623 DOI: 10.1021/jp903954t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Atomic multipole moments are used to investigate vibrational frequency shifts of CO and H(2) in uniform and inhomogeneous electric fields using ab initio calculations and Molecular Dynamics (MD) simulations. The importance of using atomic multipole moments that can accurately represent both molecular electrostatics and the vibrational response of the molecule to changes in the local electric field is highlighted. The vibrational response of CO to applied uniform and inhomogeneous electric fields is examined using Density Functional Theory calculations for a range of test fields, and the results are used to assess the performance of different atomic multipole models. In uniform fields, the calculated Stark tuning rates of Deltamu = 0.52 cm(-1)/(MV/cm) (DFT), Deltamu = 0.55 cm(-1)/(MV/cm) (fluctuating three-point charge model), and Deltamu = 0.64 cm(-1)/(MV/cm) (Multipole model up to octupole), compare favorably with the experimentally measured value of 0.67 cm(-1)/(MV/cm). For H(2), which has no permanent dipole moment, CCSD(T) calculations demonstrate the importance of bond-weakening effects in force fields in response to the applied inhomogeneous electric field. Finally, CO in hexagonal ice is considered as a test system to highlight the performance of selected multipolar models in MD simulations. The approach discussed here can be applied to calibrate a range of multipolar charge models for diatomic probes, with applications to interpret Stark spectroscopy measurements in protein active sites.
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Affiliation(s)
- Michael Devereux
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland.
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43
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Devereux M, Meuwly M. Anharmonic Coupling in Molecular Dynamics Simulations of Ligand Vibrational Relaxation in Bound Carbonmonoxy Myoglobin. J Phys Chem B 2009; 113:13061-70. [DOI: 10.1021/jp903741v] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Michael Devereux
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
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44
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Devereux M, Meuwly M. Structural assignment of spectra by characterization of conformational substates in bound MbCO. Biophys J 2009; 96:4363-75. [PMID: 19486661 DOI: 10.1016/j.bpj.2009.01.064] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 12/18/2008] [Accepted: 01/21/2009] [Indexed: 11/18/2022] Open
Abstract
Residue motions of the distal heme pocket and bound CO ligand of carbonmonoxy Myoglobin are studied using a combination of molecular dynamics simulations and quantum chemical methods. Using mixed quantum mechanics/molecular mechanics calculations together with sampling from molecular dynamics simulations (QM/MM(MD)), the experimentally observed spectroscopic A(0) and A(1) substates of the bound CO ligand are assigned to the open and closed conformation of His(64) and the His(epsilon)(64) tautomer, respectively. Several previously proposed origins of the A(3) substate, including rotamers of the doubly protonated His(64)H(+) side chain, His(64)H(+) inside the distal pocket, and cooperative motions with Arg(45), are investigated with QM/MM(MD). However, the signatures of the calculated infrared spectra do not agree with the experimentally observed ones. For additional insight on this, extensive molecular dynamics simulations are used together with improved electrostatics for the bound ligand. A CO fluctuating charge model is developed to describe the ab initio dipole and quadrupole moments of the bound ligand. CO absorption spectra are then obtained directly from the dynamics simulations. Finally, the electrostatics of the heme pocket is examined in detail in an attempt to determine the structural origins of the observed spectroscopic A-states from MD simulations. However, contrary to related simulations for unbound CO in myoglobin, the shifts and splittings for carbonmonoxy Myoglobin are generally small and difficult to relate to structural change. This suggests that coupling of the CO motion to other degrees of freedom, such as the Fe-CO stretching and bending, is important to correctly describe the dynamics of bound CO in myoglobin.
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Affiliation(s)
- Michael Devereux
- Department of Chemistry, University of Basel, Basel, Switzerland
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45
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Guo L, Park J, Lee T, Chowdhury P, Lim M, Gai F. Probing the role of hydration in the unfolding transitions of carbonmonoxy myoglobin and apomyoglobin. J Phys Chem B 2009; 113:6158-63. [PMID: 19348439 DOI: 10.1021/jp900009x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We show that the equilibrium unfolding transition of horse carbonmonoxy myoglobin monitored by the stretching vibration of the CO ligand, a local environmental probe, is very sharp and, thus, quite different from those measured by global conformational reporters. In addition, the denatured protein exhibits an A(0)-like CO band. We hypothesize that this sharp transition reports penetration of water into the heme pocket of the protein. Parallel experiments on horse apomyoglobin, wherein an environment-sensitive fluorescent probe, nile red, was used, also reveals a similar putative hydration event. Given the importance of dehydration in protein folding and also the recent debate over the interpretation of probe-dependent unfolding transitions, these results have strong implications on the mechanism of protein folding.
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Affiliation(s)
- Lin Guo
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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46
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Fayer M. Dynamics of Liquids, Molecules, and Proteins Measured with Ultrafast 2D IR Vibrational Echo Chemical Exchange Spectroscopy. Annu Rev Phys Chem 2009; 60:21-38. [PMID: 18851709 DOI: 10.1146/annurev-physchem-073108-112712] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- M.D. Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305;
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47
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Rebinding Dynamics of CO Following Photodissociation of 4.0 M Guanidine HCl-Denatured Carbonmonoxyhemoglobin. B KOREAN CHEM SOC 2009. [DOI: 10.5012/bkcs.2009.30.4.913] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Schmidt M, Achterhold K, Prusakov V, Parak FG. Protein dynamics of a β-sheet protein. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 38:687-700. [DOI: 10.1007/s00249-009-0427-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 02/12/2009] [Accepted: 02/16/2009] [Indexed: 11/29/2022]
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Abstract
Protein functions require conformational motions. We show here that the dominant conformational motions are slaved by the hydration shell and the bulk solvent. The protein contributes the structure necessary for function. We formulate a model that is based on experiments, insights from the physics of glass-forming liquids, and the concepts of a hierarchically organized energy landscape. To explore the effect of external fluctuations on protein dynamics, we measure the fluctuations in the bulk solvent and the hydration shell with broadband dielectric spectroscopy and compare them with internal fluctuations measured with the Mössbauer effect and neutron scattering. The result is clear. Large-scale protein motions are slaved to the fluctuations in the bulk solvent. They are controlled by the solvent viscosity, and are absent in a solid environment. Internal protein motions are slaved to the beta fluctuations of the hydration shell, are controlled by hydration, and are absent in a dehydrated protein. The model quantitatively predicts the rapid increase of the mean-square displacement above approximately 200 K, shows that the external beta fluctuations determine the temperature- and time-dependence of the passage of carbon monoxide through myoglobin, and explains the nonexponential time dependence of the protein relaxation after photodissociation.
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Abstract
Vibrational changes associated with CO recombination to ferrous horseradish peroxidase were investigated by rapid-scan FTIR (Fourier-transform IR) spectroscopy in the 1200-2200 cm(-1) range. At pH 6.0, two conformers of bound CO are present that appear as negative bands at 1905 and 1934 cm(-1) in photolysis spectra. Their recombination rate constants are identical, confirming that they arise from two substates of bound CO that are in rapid thermal equilibrium, rather than from heterogeneous protein sites. A smaller positive band at 2134 cm(-1) also appears on photolysis and decays with the same rate constant, indicative of an intraprotein geminate site involved in recombination or, possibly, a weak-affinity surface CO-binding site. Other signals arising from protein and haem in the 1700-1200 cm(-1) range can also be time-resolved with similar kinetics.
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