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Mokdad A, Ang E, Desciak M, Ott C, Vilbert A, Beddow O, Butuc A, Larsen RW, Reynolds MF. Photoacoustic Calorimetry Studies of O 2-Sensing FixL and (R200, I209) Variants from Sinorhizobium meliloti Reveal Conformational Changes Coupled to Ligand Photodissociation from the Heme-PAS Domain. Biochemistry 2024; 63:116-127. [PMID: 38127721 PMCID: PMC10765370 DOI: 10.1021/acs.biochem.3c00438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 11/29/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023]
Abstract
FixL is an oxygen-sensing heme-PAS protein that regulates nitrogen fixation in the root nodules of plants. In this paper, we present the first photothermal studies of the full-length wild-type FixL protein from Sinorhizobium meliloti and the first thermodynamic profile of a full-length heme-PAS protein. Photoacoustic calorimetry studies reveal a quadriphasic relaxation for SmFixL*WT and the five variant proteins (SmFixL*R200H, SmFixL*R200Q, SmFixL*R200E, SmFixL*R200A, and SmFixL*I209M) with four intermediates from <20 ns to ∼1.5 μs associated with the photodissociation of CO from the heme. The altered thermodynamic profiles of the full-length SmFixL* variant proteins confirm that the conserved heme domain residues R200 and I209 are important for signal transduction. In contrast, the truncated heme domain, SmFixLH128-264, shows only a single, fast monophasic relaxation at <50 ns associated with the fast disruption of a salt bridge and release of CO to the solvent, suggesting that the full-length protein is necessary to observe the conformational changes that propagate the signal from the heme domain to the kinase domain.
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Affiliation(s)
- Audrey Mokdad
- Department
of Chemistry, University of South Florida, 4202 East Fowler Avenue SCA 400, Tampa, Florida 33620, United States
| | - EuTchen Ang
- Department
of Chemistry and Biochemistry, Saint Joseph’s
University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States
| | - Michael Desciak
- Department
of Chemistry and Biochemistry, Saint Joseph’s
University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States
| | - Christine Ott
- Department
of Chemistry and Biochemistry, Saint Joseph’s
University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States
| | - Avery Vilbert
- Department
of Chemistry and Biochemistry, Saint Joseph’s
University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States
| | - Olivia Beddow
- Department
of Chemistry and Biochemistry, Saint Joseph’s
University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States
| | - Artiom Butuc
- Department
of Chemistry and Biochemistry, Saint Joseph’s
University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States
| | - Randy W. Larsen
- Department
of Chemistry, University of South Florida, 4202 East Fowler Avenue SCA 400, Tampa, Florida 33620, United States
| | - Mark F. Reynolds
- Department
of Chemistry and Biochemistry, Saint Joseph’s
University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States
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Garg M, Sharma D, Kumar R. Analysis of the effect of 1-Allyl-3-Methylimidazolium chloride on thermodynamic stability, folding kinetics, and motional dynamics of horse cytochrome c. Biophys Chem 2022; 290:106892. [PMID: 36115294 DOI: 10.1016/j.bpc.2022.106892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 09/03/2022] [Accepted: 09/04/2022] [Indexed: 11/02/2022]
Abstract
1-allyl-3-methylimidazolium chloride (AMIMCl) acts as a potential green solvent for proteins. The present work provides a possible pathway by which the structural, kinetic, thermodynamic, and folding properties of horse cytochrome c (cyt c) are affected in green aqueous-AMIMCl systems. Analysis of the effect of AMIMCl on thermodynamic stability, refolding/unfolding kinetics, and motional dynamics of cyt c provided important information, (i) AMIMCl decreases the thermodynamic stability of reduced cyt c and also strengthens the guanidinium chloride (GdmCl)-mediated decrease in thermodynamic stability of protein, (ii) AMIMCl reduces the thermal-fluctuation of Met80-containing omega-loop of natively-folded compact state of carbonmonoxycytochrome c (MCO-state) due to polyfunctional interactions between the AMIM+ and different groups of protein, (iii) AMIMCl shifts the kinetic chevron plot, ln kobs[GdmCl] to the lower concentration of GdmCl, (iv) AMIMCl shifts the refolding and unfolding limps to vertically downwards and upwards, respectively, and (v) AMIMCl reducing the unfolding free energy estimated by both thermodynamic and kinetic analysis.
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Affiliation(s)
- Mansi Garg
- Department of Chemistry, Central University of Punjab, Bathinda 151001, India
| | - Deepak Sharma
- Council of Scientific and Industrial Research- Institute of Microbial Technology, Sector 39A, Chandigarh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Rajesh Kumar
- Department of Chemistry, Central University of Punjab, Bathinda 151001, India.
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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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Effect of imidazolium based ionic liquids on CO-association dynamics and thermodynamic stability of Ferrocytochrome c. Biophys Chem 2020; 268:106497. [PMID: 33212391 DOI: 10.1016/j.bpc.2020.106497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 11/01/2020] [Accepted: 11/01/2020] [Indexed: 11/20/2022]
Abstract
Analysis of kinetic and thermodynamic parameters measured for CO-association reaction of Ferrocytochrome c (Ferrocyt c) under variable concentrations of 1-butyl-3-methylimidazolium with varying anion ([Bmim]X) (X = Cl-, I-, Br-, HSO4-) at pH 7 revealed that the low concentration of [Bmim]X (≤0.5 M) constrains the CO-association dynamics of Ferrocyt c and typically follows the order: [Bmim]HSO4 > [Bmim]Cl > [Bmim]Br > [Bmim]I. At relatively higher concentrations (>0.5), the chaotropic action of [Bmim]+ dominates which consequently increases the thermal-fluctuations responsible to denature the protein and thus accelerates the speed of CO-association reaction. Analysis of thermal denaturation curves of Ferrocyt c measured at different concentrations of [Bmim]X revealed that the [Bmim]X decreases the thermodynamic stability of protein and typically follows the order: [Bmim]I > [Bmim]Br > [Bmim]Cl > [Bmim]CH3COO > [Bmim]HSO4, demonstrating that the effect of [Bmim]X on thermodynamic stability of protein is not in accordance to Hofmeister series effect of anions because instead of increasing the kosmotropic anion carrying [Bmim]X ([Bmim]CH3COO and [Bmim]HSO4) also decreases the thermodynamic stability of protein.
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5
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Jain R, Sharma D, Kumar R, Kumar R. Structural, kinetic and thermodynamic characterizations of SDS-induced molten globule state of a highly negatively charged cytochrome c. J Biochem 2019; 165:125-137. [PMID: 30371870 DOI: 10.1093/jb/mvy087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 10/26/2018] [Indexed: 11/14/2022] Open
Abstract
This study presents the structural, kinetic and thermodynamic characterizations of previously unknown submicellar concentrations of SDS-induced molten globule (MGSDS) state of a highly negatively charged base-denatured ferricytochrome c (UB-state) at pH ∼12.8 (±0.2). The far-UV CD, near-UV CD, ANS-fluorescence data of UB-state in the presence of different concentrations of SDS indicate that the submicellar concentrations of SDS (≤0.4 mM) transform the UB-state to MGSDS-state. The MGSDS-state has native-like α-helical secondary structure but lacks tertiary structure. The free energy change (ΔG°D) for UB→ MGSDS transition determined by far-UV CD (∼2.7 kcal mol-1) is slightly higher than those determined by fluorescence (∼2.0 kcal mol-1) at 25°C. At very low SDS and NaCl concentrations, the MGSDS-state undergoes cold denaturation. As SDS concentration is increased, the thermal denaturation temperature increases and the cold denaturation temperature decrease. Kinetic experiments involving the measurement of the CO-association rate to the base-denatured ferrocytochrome c at pH ≈12.8 (±0.2), 25°C indicate that the submicellar concentrations of SDS restrict the internal dynamics of base-denatured protein.
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Affiliation(s)
- Rishu Jain
- School of Chemistry and Biochemistry, Thapar University, Patiala, India.,Department of Chemistry, Gujranwala Guru Nanak Khalsa College, Ghumar Mandi, Civil Lines, Ludhiana, India
| | - Deepak Sharma
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39A, Chandigarh, India
| | - Rakesh Kumar
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39A, Chandigarh, India
| | - Rajesh Kumar
- School of Chemistry and Biochemistry, Thapar University, Patiala, India.,School of Basic and Applied Sciences, Department of Chemical Sciences, Central University of Punjab, Bathinda, India
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6
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Carlson GM, Fenton AW. What Mutagenesis Can and Cannot Reveal About Allostery. Biophys J 2017; 110:1912-23. [PMID: 27166800 DOI: 10.1016/j.bpj.2016.03.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/24/2016] [Accepted: 03/14/2016] [Indexed: 10/21/2022] Open
Abstract
Allosteric regulation of protein function is recognized to be widespread throughout biology; however, knowledge of allosteric mechanisms, the molecular changes within a protein that couple one binding site to another, is limited. Although mutagenesis is often used to probe allosteric mechanisms, we consider herein what the outcome of a mutagenesis study truly reveals about an allosteric mechanism. Arguably, the best way to evaluate the effects of a mutation on allostery is to monitor the allosteric coupling constant (Qax), a ratio of the substrate binding constants in the absence versus presence of an allosteric effector. A range of substitutions at a given residue position in a protein can reveal when a particular substitution causes gain-of-function, which addresses a key challenge in interpreting mutation-dependent changes in the magnitude of Qax. Thus, whole-protein mutagenesis studies offer an acceptable means of identifying residues that contribute to an allosteric mechanism. With this focus on monitoring Qax, and keeping in mind the equilibrium nature of allostery, we consider alternative possibilities for what an allosteric mechanism might be. We conclude that different possible mechanisms (rotation-of-solid-domains, movement of secondary structure, side-chain repacking, changes in dynamics, etc.) will result in different findings in whole-protein mutagenesis studies.
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Affiliation(s)
- Gerald M Carlson
- Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas
| | - Aron W Fenton
- Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas.
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Kumar S, Sharma D, Kumar R. Effect of urea and alkylureas on the stability and structural fluctuation of the M80-containing Ω-loop of horse cytochrome c. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:641-55. [DOI: 10.1016/j.bbapap.2014.01.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/10/2014] [Accepted: 01/22/2014] [Indexed: 11/27/2022]
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Marcelli A, Abbruzzetti S, Bustamante JP, Feis A, Bonamore A, Boffi A, Gellini C, Salvi PR, Estrin DA, Bruno S, Viappiani C, Foggi P. Following ligand migration pathways from picoseconds to milliseconds in type II truncated hemoglobin from Thermobifida fusca. PLoS One 2012; 7:e39884. [PMID: 22792194 PMCID: PMC3391200 DOI: 10.1371/journal.pone.0039884] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 05/28/2012] [Indexed: 11/18/2022] Open
Abstract
CO recombination kinetics has been investigated in the type II truncated hemoglobin from Thermobifida fusca (Tf-trHb) over more than 10 time decades (from 1 ps to ∼100 ms) by combining femtosecond transient absorption, nanosecond laser flash photolysis and optoacoustic spectroscopy. Photolysis is followed by a rapid geminate recombination with a time constant of ∼2 ns representing almost 60% of the overall reaction. An additional, small amplitude geminate recombination was identified at ∼100 ns. Finally, CO pressure dependent measurements brought out the presence of two transient species in the second order rebinding phase, with time constants ranging from ∼3 to ∼100 ms. The available experimental evidence suggests that the two transients are due to the presence of two conformations which do not interconvert within the time frame of the experiment. Computational studies revealed that the plasticity of protein structure is able to define a branched pathway connecting the ligand binding site and the solvent. This allowed to build a kinetic model capable of describing the complete time course of the CO rebinding kinetics to Tf-trHb.
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Affiliation(s)
- Agnese Marcelli
- LENS, European Laboratory for Non-linear Spectroscopy, Florence, Italy.
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9
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Time resolved thermodynamics associated with ligand photorelease in heme peroxidases and globins: Open access channels versus gated ligand release. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1065-76. [PMID: 21278003 DOI: 10.1016/j.bbapap.2011.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 01/14/2011] [Accepted: 01/17/2011] [Indexed: 10/18/2022]
Abstract
Heme proteins represent a diverse class of biomolecules responsible for an extremely diverse array of physiological functions including electron transport, monooxygenation, ligand transport and storage, cellular signaling, respiration, etc. An intriguing aspect of these proteins is that such functional diversity is accomplished using a single type of heme macrocycle based upon iron protoporphyrin IX. The functional diversity originates from a delicate balance of inter-molecular interactions within the protein matrix together with well choreographed dynamics that modulate the heme electronic structure as well as ligand entry/exit pathways from the bulk solvent to the active site. Of particular interest are the dynamics and energetics associated with the entry/exit of ligands as this process plays a significant role in regulating the rates of heme protein activity. Time-resolved photoacoustic calorimetry (PAC) has emerged as a powerful tool through which to probe the underlying energetics associated with small molecule dissociation and release to the bulk solvent in heme proteins on time scales from tens of nanoseconds to several microseconds. In this review, the results of PAC studies on various classes of heme proteins are summarized highlighting how different protein structures affect the thermodynamics of ligand migration. This article is part of a Special Issue entitled: Protein Dynamics: Experimental and Computational Approaches.
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10
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Mokdad A, Nissen M, Satterlee JD, Larsen RW. Evidence for fast conformational change upon ligand dissociation in the HemAT class of bacterial oxygen sensors. FEBS Lett 2007; 581:4512-8. [PMID: 17765225 DOI: 10.1016/j.febslet.2007.08.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 08/13/2007] [Accepted: 08/14/2007] [Indexed: 10/22/2022]
Abstract
Here we report the results of transient absorption and photoacoustic calorimetry studies of CO photodissociation from the heme domain of the bacterial oxygen sensor HemAT-Bs. The results indicate that CO photolysis is accompanied by an overall DeltaH of -19 kcal mol(-1) and DeltaV of +4 ml mol(-1) as well as a red-shifted kinetic difference spectrum all occurring in <50 ns. Analysis of the DeltaH/DeltaV reveals that a conformational change takes place with a DeltaH(conf) of -40 kcal mol(-1) and DeltaV(conf) of -22 ml mol(-1). These thermodynamic changes are consistent with an increase in the solvent accessible surface area of the protein upon ligand dissociation, as observed in the X-ray structure of the ferric CN-bound and CN free forms of HemAT-Bs.
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Affiliation(s)
- Audrey Mokdad
- Department of Chemistry, University of South Florida, 4202 East Fowler Ave., Tampa, FL 33620, United States
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12
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Oertling WA, Cornellison CD, Treff NR, Watanabe J, Pressler MA, Small JR. Photoacoustic characterization of protein dynamics following CO photodetachment from fully reduced bovine cytochrome c oxidase. J Inorg Biochem 2007; 101:635-43. [PMID: 17280717 DOI: 10.1016/j.jinorgbio.2006.12.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2006] [Revised: 12/08/2006] [Accepted: 12/12/2006] [Indexed: 11/25/2022]
Abstract
We report a protein conformational change following carbon monoxide photodetachment from fully reduced bovine cytochrome c oxidase that is hypothesized to be associated with changes in ligand mobility through a dioxygen access channel in the protein. Although not resolved by earlier photoacoustic or optical studies on this adduct, utilization of slightly lower temperatures revealed a process with a kinetic lifetime of about 70 ns at 10 degrees C. We measure an enthalpy change of about 8 kcal/mol in 0.050 M HEPES buffer that becomes less endothermic (DeltaH approximately 2 kcal/mol) at higher ionic strength. The volume contraction of about -0.7 mL/mol associated with the process almost doubles in higher ionic strength buffer systems. Measurements of samples in phosphate buffer systems are similar and appear to display the same subtle ionic strength dependence. Both the isolation of this photoacoustic signal component and the possible dependence on ionic strength of the thermodynamic parameters derived from its analysis appear analogous to and consistent with prior photoacoustic results monitoring CO photodetachment from the camphor complex of cytochrome P-450. Accordingly, we consider a similar model in which a conformational change results in movement of an exposed charged group or groups towards the interior of the protein, out of contact with solvent, as in the closing of a salt bridge.
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Affiliation(s)
- W Anthony Oertling
- Department of Chemistry and Biochemistry, 226 Science Building, Eastern Washington University, Cheney, WA 99004-2440, USA.
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Walther M, Raicu V, Ogilvie JP, Phillips R, Kluger R, Miller RJD. Determination of the Fe−CO Bond Energy in Myoglobin Using Heterodyne-Detected Transient Thermal Phase Grating Spectroscopy. J Phys Chem B 2005; 109:20605-11. [PMID: 16853667 DOI: 10.1021/jp052344n] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bond energies at active sites of proteins are intimately coupled to the structure-function relationship in biological systems. Due to the unknown nature of the protein relaxation along a reaction coordinate, it has not been possible to directly determine bond energies relevant to protein function. By embedding proteins in trehalose glasses, it is possible to freeze out protein relaxation on short time scales and determine the bond energies of photolabile ligands using photothermal spectroscopies. As a prototypical example, the photodissociation dynamics and energetics of carboxy-myoglobin (MbCO) in a trehalose glass matrix at room temperature were studied by transient absorption (or pump-probe) and transient thermal phase grating spectroscopy to determine the CO recombination dynamics and associated energetics, respectively. Both the initial energetics of the bond breaking and the energy released upon bond reformation could be used, on a time scale faster than significant protein relaxation, to determine the Fe-CO bond energy as 34 +/- 4 kcal/mol. This bond energy is significantly larger than that typically cited (25 kcal/mol) on the basis of indirect measurements but is in good agreement with recent theoretical predictions (35 kcal/mol) (Rovira, C.; Parrinello, M. Int. J. Quantum Chem. 2000, 80, 1172). This result in combination with the theoretical study suggests that protein structure plays a significant role in the bond energies at active sites which in turn provides a tuning element of the effective barrier heights independent to the transition state region.
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Affiliation(s)
- Markus Walther
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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