151
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Nagaoka SI, Nitta A, Suemitsu A, Mukai K. Tunneling effect in vitamin E recycling by green tea. RSC Adv 2016. [DOI: 10.1039/c6ra05986d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A tunneling effect was found to play an important role in vitamin E recycling reactions by catechins contained in green tea.
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Affiliation(s)
- Shin-ichi Nagaoka
- Department of Chemistry
- Faculty of Science and Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
| | - Akiko Nitta
- Department of Chemistry
- Faculty of Science and Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
| | - Ai Suemitsu
- Department of Chemistry
- Faculty of Science and Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
| | - Kazuo Mukai
- Department of Chemistry
- Faculty of Science and Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
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152
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Abeysinghe T, Hong B, Wang Z, Kohen A. Preserved hydride transfer mechanism in evolutionarily divergent thymidylate synthases. CURRENT TOPICS IN BIOCHEMICAL RESEARCH 2016; 17:19-30. [PMID: 28018055 PMCID: PMC5172458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Thymidylate synthase (TSase) catalyzes a hydride transfer in the last step of the de novo biosynthesis of the DNA nucleotide thymine. We compared two isozymes, namely, TSase from Escherichia coli (ecTSase) and TSase from Bacillus subtilis (bsTSase) that represent a case of divergent evolution. Interestingly, a highly conserved histidine (H147 of ecTSase) was proposed to serve a critical role in catalysis, but in bsTSase it is naturally substituted by valine (Val). Yet, bsTSase is more active than ecTSase, and the intrinsic kinetic isotope effects (KIEs) of both are temperature-independent, suggesting a similarly well-organized transition state (TS) for the catalyzed hydride transfer. To examine the role of that histidine (His) in TSase catalysis, we examined the kinetics of H147V ecTSase, which "bridges" between these two TSases. In contrast to both wild-type TSases, the single mutation results in deficient catalysis. The mutation leads to intrinsic KIEs that are temperature-dependent, indicating a substantial imperfection in its TS. The findings reveal two important features: a direct role of H147 in the hydride transfer step catalyzed by the ecTSase and the evolutionary compensation for its deficiency in bsTSase via extensive polymorphism across the protein. Very different active site residues are observed for these evolutionarily divergent isozymes, which result in a well-organized TS for both. It is suggested that evolutionary pressure compensated for the H to V substitution at the active site of bsTSase by polymorphism leading to a well-organized TS in both enzymes.
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Affiliation(s)
- Thelma Abeysinghe
- Department of Chemistry, The University of Iowa, Iowa City, IA 52242, USA
| | - Baoyu Hong
- Department of Chemistry, The University of Iowa, Iowa City, IA 52242, USA
- Genentech, South San Francisco, CA 94080, USA
| | - Zhen Wang
- Department of Chemistry, The University of Iowa, Iowa City, IA 52242, USA
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Amnon Kohen
- Department of Chemistry, The University of Iowa, Iowa City, IA 52242, USA
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153
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Konkle ME, Blobaum AL, Moth CW, Prusakiewicz JJ, Xu S, Ghebreselasie K, Akingbade D, Jacobs AT, Rouzer CA, Lybrand TP, Marnett LJ. Conservative Secondary Shell Substitution In Cyclooxygenase-2 Reduces Inhibition by Indomethacin Amides and Esters via Altered Enzyme Dynamics. Biochemistry 2015; 55:348-59. [PMID: 26704937 PMCID: PMC4721528 DOI: 10.1021/acs.biochem.5b01222] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The cyclooxygenase enzymes (COX-1 and COX-2) are the therapeutic targets of nonsteroidal anti-inflammatory drugs (NSAIDs). Neutralization of the carboxylic acid moiety of the NSAID indomethacin to an ester or amide functionality confers COX-2 selectivity, but the molecular basis for this selectivity has not been completely revealed through mutagenesis studies and/or X-ray crystallographic attempts. We expressed and assayed a number of divergent secondary shell COX-2 active site mutants and found that a COX-2 to COX-1 change at position 472 (Leu in COX-2, Met in COX-1) reduced the potency of enzyme inhibition by a series of COX-2-selective indomethacin amides and esters. In contrast, the potencies of indomethacin, arylacetic acid, propionic acid, and COX-2-selective diarylheterocycle inhibitors were either unaffected or only mildly affected by this mutation. Molecular dynamics simulations revealed identical equilibrium enzyme structures around residue 472; however, calculations indicated that the L472M mutation impacted local low-frequency dynamical COX constriction site motions by stabilizing the active site entrance and slowing constriction site dynamics. Kinetic analysis of inhibitor binding is consistent with the computational findings.
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Affiliation(s)
- Mary E Konkle
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Anna L Blobaum
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Christopher W Moth
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Jeffery J Prusakiewicz
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Shu Xu
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Kebreab Ghebreselasie
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Dapo Akingbade
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Aaron T Jacobs
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Carol A Rouzer
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Terry P Lybrand
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Lawrence J Marnett
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
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154
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Wang Z, Antoniou D, Schwartz SD, Schramm VL. Hydride Transfer in DHFR by Transition Path Sampling, Kinetic Isotope Effects, and Heavy Enzyme Studies. Biochemistry 2015; 55:157-66. [PMID: 26652185 DOI: 10.1021/acs.biochem.5b01241] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Escherichia coli dihydrofolate reductase (ecDHFR) is used to study fundamental principles of enzyme catalysis. It remains controversial whether fast protein motions are coupled to the hydride transfer catalyzed by ecDHFR. Previous studies with heavy ecDHFR proteins labeled with (13)C, (15)N, and nonexchangeable (2)H reported enzyme mass-dependent hydride transfer kinetics for ecDHFR. Here, we report refined experimental and computational studies to establish that hydride transfer is independent of protein mass. Instead, we found the rate constant for substrate dissociation to be faster for heavy DHFR. Previously reported kinetic differences between light and heavy DHFRs likely arise from kinetic steps other than the chemical step. This study confirms that fast (femtosecond to picosecond) protein motions in ecDHFR are not coupled to hydride transfer and provides an integrative computational and experimental approach to resolve fast dynamics coupled to chemical steps in enzyme catalysis.
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Affiliation(s)
- Zhen Wang
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Dimitri Antoniou
- Department of Chemistry and Biochemistry, University of Arizona , P.O. Box 210041, 1306 East University Boulevard, Tucson, Arizona 85721, United States
| | - Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona , P.O. Box 210041, 1306 East University Boulevard, Tucson, Arizona 85721, United States
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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155
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Abstract
Dihydrofolate reductase from
Escherichia coli (ecDHFR) serves as a model system for investigating the role of protein dynamics in enzyme catalysis. We discuss calculations predicting a network of dynamic motions that is coupled to the chemical step catalyzed by this enzyme. Kinetic studies testing these predictions are presented, and their potential use in better understanding the role of these dynamics in enzyme catalysis is considered. The cumulative results implicate motions across the entire protein in catalysis.
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Affiliation(s)
- Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA, USA
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156
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Ghosh AK, Islam Z, Krueger J, Abeysinghe T, Kohen A. The general base in the thymidylate synthase catalyzed proton abstraction. Phys Chem Chem Phys 2015; 17:30867-75. [PMID: 25912171 PMCID: PMC4624062 DOI: 10.1039/c5cp01246e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The enzyme thymidylate synthase (TSase), an important chemotherapeutic drug target, catalyzes the formation of 2'-deoxythymidine-5'-monophosphate (dTMP), a precursor of one of the DNA building blocks. TSase catalyzes a multi-step mechanism that includes the abstraction of a proton from the C5 of the substrate 2'-deoxyuridine-5'-monophosphate (dUMP). Previous studies on ecTSase proposed that an active-site residue, Y94 serves the role of the general base abstracting this proton. However, since Y94 is neither very basic, nor connected to basic residues, nor located close enough to the pyrimidine proton to be abstracted, the actual identity of this base remains enigmatic. Based on crystal structures, an alternative hypothesis is that the nearest potential proton-acceptor of C5 of dUMP is a water molecule that is part of a hydrogen bond (H-bond) network comprised of several water molecules and several protein residues including H147, E58, N177, and Y94. Here, we examine the role of the residue Y94 in the proton abstraction step by removing its hydroxyl group (Y94F mutant). We investigated the effect of the mutation on the temperature dependence of intrinsic kinetic isotope effects (KIEs) and found that these KIEs are more temperature dependent than those of the wild-type enzyme (WT). These results suggest that the phenolic -OH of Y94 is a component of the transition state for the proton abstraction step. The findings further support the hypothesis that no single functional group is the general base, but a network of bases and hydroxyls (from water molecules and tyrosine) sharing H-bonds across the active site can serve the role of the general base to remove the pyrimidine proton.
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Affiliation(s)
- Ananda K Ghosh
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
| | - Zahidul Islam
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
| | - Jonathan Krueger
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
| | - Thelma Abeysinghe
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
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157
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Zhai X, Amyes TL, Richard JP. Role of Loop-Clamping Side Chains in Catalysis by Triosephosphate Isomerase. J Am Chem Soc 2015; 137:15185-97. [PMID: 26570983 PMCID: PMC4694050 DOI: 10.1021/jacs.5b09328] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The side chains of
Y208 and S211 from loop 7 of triosephosphate
isomerase (TIM) form hydrogen bonds to backbone amides and carbonyls
from loop 6 to stabilize the caged enzyme–substrate complex.
The effect of seven mutations [Y208T, Y208S, Y208A, Y208F, S211G,
S211A, Y208T/S211G] on the kinetic parameters for TIM catalyzed reactions
of the whole substrates dihydroxyacetone phosphate and d-glyceraldehyde
3-phosphate [(kcat/Km)GAP and (kcat/Km)DHAP] and of the substrate pieces
glycolaldehyde and phosphite dianion (kcat/KHPiKGA)
are reported. The linear logarithmic correlation between these kinetic
parameters, with slope of 1.04 ± 0.03, shows that most mutations
of TIM result in an identical change in the activation barriers for
the catalyzed reactions of whole substrate and substrate pieces, so
that the transition states for these reactions are stabilized by similar
interactions with the protein catalyst. The second linear logarithmic
correlation [slope = 0.53 ± 0.16] between kcat for isomerization of GAP and Kd⧧ for phosphite dianion binding to the transition
state for wildtype and many mutant TIM-catalyzed reactions of substrate
pieces shows that ca. 50% of the wildtype TIM dianion binding energy,
eliminated by these mutations, is expressed at the wildtype Michaelis
complex, and ca. 50% is only expressed at the wildtype transition
state. Negative deviations from this correlation are observed when
the mutation results in a decrease in enzyme reactivity at the catalytic
site. The main effect of Y208T, Y208S, and Y208A mutations is to cause
a reduction in the total intrinsic dianion binding energy, but the
effect of Y208F extends to the catalytic site.
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Affiliation(s)
- Xiang Zhai
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
| | - Tina L Amyes
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
| | - John P Richard
- Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States
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158
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Gagné D, French RL, Narayanan C, Simonović M, Agarwal PK, Doucet N. Perturbation of the Conformational Dynamics of an Active-Site Loop Alters Enzyme Activity. Structure 2015; 23:2256-2266. [PMID: 26655472 DOI: 10.1016/j.str.2015.10.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 10/05/2015] [Accepted: 10/13/2015] [Indexed: 01/28/2023]
Abstract
The role of internal dynamics in enzyme function is highly debated. Specifically, how small changes in structure far away from the reaction site alter protein dynamics and overall enzyme mechanisms is of wide interest in protein engineering. Using RNase A as a model, we demonstrate that elimination of a single methyl group located >10 Å away from the reaction site significantly alters conformational integrity and binding properties of the enzyme. This A109G mutation does not perturb structure or thermodynamic stability, both in the apo and ligand-bound states. However, significant enhancement in conformational dynamics was observed for the bound variant, as probed over nano- to millisecond timescales, resulting in major ligand repositioning. These results illustrate the large effects caused by small changes in structure on long-range conformational dynamics and ligand specificities within proteins, further supporting the importance of preserving wild-type dynamics in enzyme systems that rely on flexibility for function.
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Affiliation(s)
- Donald Gagné
- INRS-Institut Armand-Frappier, Université du Québec, 531 Boulevard des Prairies, Laval, QC H7V 1B7, Canada
| | - Rachel L French
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 South Ashland, Chicago, IL 60607, USA
| | - Chitra Narayanan
- INRS-Institut Armand-Frappier, Université du Québec, 531 Boulevard des Prairies, Laval, QC H7V 1B7, Canada
| | - Miljan Simonović
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 South Ashland, Chicago, IL 60607, USA
| | - Pratul K Agarwal
- Computational Biology Institute and Computer Science and Mathematics Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA; Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Nicolas Doucet
- INRS-Institut Armand-Frappier, Université du Québec, 531 Boulevard des Prairies, Laval, QC H7V 1B7, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, 1045 Avenue de la Médecine, Université Laval, QC G1V 0A6, Canada; GRASP, the Groupe de Recherche Axé sur la Structure des Protéines, 3649 Promenade Sir William Osler, McGill University, Montréal, QC H3G 0B1, Canada.
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159
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Bogh SA, Bora I, Rosenberg M, Thyrhaug E, Laursen BW, Sørensen TJ. Azadioxatriangulenium: exploring the effect of a 20 ns fluorescence lifetime in fluorescence anisotropy measurements. Methods Appl Fluoresc 2015; 3:045001. [PMID: 29148501 DOI: 10.1088/2050-6120/3/4/045001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Azaoxatriangulenium (ADOTA) has been shown to be highly emissive despite a moderate molar absorption coefficient of the primary electronic transition. As a result, the fluorescence lifetime is ~20 ns, longer than all commonly used red fluorescent organic probes. The electronic transitions in ADOTA are highly polarised (r 0 = 0.38), which in combination with the long fluorescence lifetime extents the size-range of biomolecular weights that can be detected in fluorescence polarisation-based experiments. Here, the rotational dynamics of bovine serum albumin (BSA) are monitored with three different ADOTA derivatives, differing only in constitution of the reactive linker. A detailed study of the degree of labelling, the steady-state anisotropy, and the time-resolved anisotropy of the three different ADOTA-BSA conjugates are reported. The fluorescence quantum yields (ϕ fl) of the free dyes in PBS solution are determined to be ~55%, which is reduced to ~20% in the ADOTA-BSA conjugates. Despite the reduction in ϕ fl, a ~20 ns intensity averaged lifetime is maintained, allowing for the rotational dynamics of BSA to be monitored for up to 100 ns. Thus, ADOTA can be used in fluorescence polarisation assays to fill the gap between commonly used organic dyes and the long luminescence lifetime transition metal complexes. This allows for efficient steady-state fluorescence polarisation assays for detecting binding of analytes with molecular weights of up to 100 kDa.
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Affiliation(s)
- Sidsel A Bogh
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
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160
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Islam Z, Strutzenberg TS, Ghosh AK, Kohen A. Activation of Two Sequential H-transfers in the Thymidylate Synthase Catalyzed Reaction. ACS Catal 2015; 5:6061-6068. [PMID: 26576323 PMCID: PMC4643671 DOI: 10.1021/acscatal.5b01332] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thymidylate synthase (TSase) catalyzes the de novo biosynthesis of thymidylate, a precursor for DNA, and is thus an important target for chemotherapeutics and antibiotics. Two sequential C-H bond cleavages catalyzed by TSase are of particular interest: a reversible proton abstraction from the 2'-deoxy-uridylate substrate, followed by an irreversible hydride transfer forming the thymidylate product. QM/MM calculations of the former predicted a mechanism where the abstraction of the proton leads to formation of a novel nucleotide-folate intermediate that is not covalently bound to the enzyme (Wang, Z.; Ferrer, S.; Moliner, V.; Kohen, A. Biochemistry2013, 52, 2348-2358). Existence of such intermediate would hold promise as a target for a new class of drugs. Calculations of the subsequent hydride transfer predicted a concerted H-transfer and elimination of the enzymatic cysteine (Kanaan, N.; Ferrer, S.; Marti, S.; Garcia-Viloca, M.; Kohen, A.; Moliner, V. J. Am. Chem. Soc.2011, 133, 6692-6702). A key to both C-H activations is a highly conserved arginine (R166) that stabilizes the transition state of both H-transfers. Here we test these predictions by studying the R166 to lysine mutant of E. coli TSase (R166K) using intrinsic kinetic isotope effects (KIEs) and their temperature dependence to assess effects of the mutation on both chemical steps. The findings confirmed the predictions made by the QM/MM calculations, implicate R166 as an integral component of both reaction coordinates, and thus provide critical support to the nucleotide-folate intermediate as a new target for rational drug design.
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Affiliation(s)
- Zahidul Islam
- The Department of Chemistry, The University of Iowa, Iowa City, IA 52242, U.S.A
| | | | - Ananda K. Ghosh
- The Department of Chemistry, The University of Iowa, Iowa City, IA 52242, U.S.A
| | - Amnon Kohen
- The Department of Chemistry, The University of Iowa, Iowa City, IA 52242, U.S.A
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161
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Tuñón I, Laage D, Hynes JT. Are there dynamical effects in enzyme catalysis? Some thoughts concerning the enzymatic chemical step. Arch Biochem Biophys 2015; 582:42-55. [PMID: 26087289 PMCID: PMC4560206 DOI: 10.1016/j.abb.2015.06.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 06/05/2015] [Accepted: 06/06/2015] [Indexed: 11/21/2022]
Abstract
We offer some thoughts on the much debated issue of dynamical effects in enzyme catalysis, and more specifically on their potential role in the acceleration of the chemical step. Since the term 'dynamics' has been used with different meanings, we find it useful to first return to the Transition State Theory rate constant, its assumptions and the choices it involves, and detail the various sources of deviations from it due to dynamics (or not). We suggest that much can be learned about the key current questions for enzyme catalysis from prior extensive studies of dynamical and other effects in the case of reactions in solution. We analyze dynamical effects both in the neighborhood of the transition state and far from it, together with the situation when quantum nuclear motion is central to the reaction, and we illustrate our discussion with various examples of enzymatic reactions.
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Affiliation(s)
- Iñaki Tuñón
- Departamento de Química Física, Universidad de Valencia, Spain.
| | - Damien Laage
- Ecole Normale Supérieure-PSL Research University, Chemistry Department, Sorbonne Universités-UPMC University Paris 06, CNRS UMR 8640 Pasteur, 24 rue Lhomond, 75005 Paris, France.
| | - James T Hynes
- Ecole Normale Supérieure-PSL Research University, Chemistry Department, Sorbonne Universités-UPMC University Paris 06, CNRS UMR 8640 Pasteur, 24 rue Lhomond, 75005 Paris, France; Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA.
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162
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Vardi-Kilshtain A, Nitoker N, Major DT. Nuclear quantum effects and kinetic isotope effects in enzyme reactions. Arch Biochem Biophys 2015; 582:18-27. [DOI: 10.1016/j.abb.2015.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/02/2015] [Accepted: 03/03/2015] [Indexed: 11/28/2022]
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163
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Ribeiro AJM, Santos-Martins D, Russo N, Ramos MJ, Fernandes PA. Enzymatic Flexibility and Reaction Rate: A QM/MM Study of HIV-1 Protease. ACS Catal 2015. [DOI: 10.1021/acscatal.5b00759] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- António J. M. Ribeiro
- UCBIO,
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
- Dipartimento
di Chimica, Università della Calabria, 87036 Arcavacata
di Rende, Italia
| | - Diogo Santos-Martins
- UCBIO,
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Nino Russo
- Dipartimento
di Chimica, Università della Calabria, 87036 Arcavacata
di Rende, Italia
| | - Maria J. Ramos
- UCBIO,
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Pedro A. Fernandes
- UCBIO,
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
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164
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Isotope-specific and amino acid-specific heavy atom substitutions alter barrier crossing in human purine nucleoside phosphorylase. Proc Natl Acad Sci U S A 2015; 112:11247-51. [PMID: 26305965 DOI: 10.1073/pnas.1513956112] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Computational chemistry predicts that atomic motions on the femtosecond timescale are coupled to transition-state formation (barrier-crossing) in human purine nucleoside phosphorylase (PNP). The prediction is experimentally supported by slowed catalytic site chemistry in isotopically labeled PNP (13C, 15N, and 2H). However, other explanations are possible, including altered volume or bond polarization from carbon-deuterium bonds or propagation of the femtosecond bond motions into slower (nanoseconds to milliseconds) motions of the larger protein architecture to alter catalytic site chemistry. We address these possibilities by analysis of chemistry rates in isotope-specific labeled PNPs. Catalytic site chemistry was slowed for both [2H]PNP and [13C, 15N]PNP in proportion to their altered protein masses. Secondary effects emanating from carbon-deuterium bond properties can therefore be eliminated. Heavy-enzyme mass effects were probed for local or global contributions to catalytic site chemistry by generating [15N, 2H]His8-PNP. Of the eight His per subunit, three participate in contacts to the bound reactants and five are remote from the catalytic sites. [15N, 2H]His8-PNP had reduced catalytic site chemistry larger than proportional to the enzymatic mass difference. Altered barrier crossing when only His are heavy supports local catalytic site femtosecond perturbations coupled to transition-state formation. Isotope-specific and amino acid specific labels extend the use of heavy enzyme methods to distinguish global from local isotope effects.
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165
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Maharjan B, Raghibi Boroujeni M, Lefton J, White OR, Razzaghi M, Hammann BA, Derakhshani-Molayousefi M, Eilers JE, Lu Y. Steric Effects on the Primary Isotope Dependence of Secondary Kinetic Isotope Effects in Hydride Transfer Reactions in Solution: Caused by the Isotopically Different Tunneling Ready State Conformations? J Am Chem Soc 2015; 137:6653-61. [DOI: 10.1021/jacs.5b03085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Binita Maharjan
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, United States
| | - Mahdi Raghibi Boroujeni
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, United States
| | - Jonathan Lefton
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, United States
| | - Ormacinda R. White
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, United States
| | - Mortezaali Razzaghi
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, United States
| | - Blake A. Hammann
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, United States
| | | | - James E. Eilers
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, United States
| | - Yun Lu
- Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, Illinois 62026, United States
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166
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Roberts G. The role of protein dynamics in allosteric effects-introduction. Biophys Rev 2015; 7:161-163. [PMID: 28510175 DOI: 10.1007/s12551-015-0174-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 04/13/2015] [Indexed: 10/23/2022] Open
Affiliation(s)
- Gordon Roberts
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN, UK.
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167
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Jones AR, Rentergent J, Scrutton NS, Hay S. Probing reversible chemistry in coenzyme B12 -dependent ethanolamine ammonia lyase with kinetic isotope effects. Chemistry 2015; 21:8826-31. [PMID: 25950663 PMCID: PMC4497352 DOI: 10.1002/chem.201500958] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Indexed: 01/20/2023]
Abstract
Coenzyme B12-dependent enzymes such as ethanolamine ammonia lyase have remarkable catalytic power and some unique properties that enable detailed analysis of the reaction chemistry and associated dynamics. By selectively deuterating the substrate (ethanolamine) and/or the β-carbon of the 5′-deoxyadenosyl moiety of the intrinsic coenzyme B12, it was possible to experimentally probe both the forward and reverse hydrogen atom transfers between the 5′-deoxyadenosyl radical and substrate during single-turnover stopped-flow measurements. These data are interpreted within the context of a kinetic model where the 5′-deoxyadenosyl radical intermediate may be quasi-stable and rearrangement of the substrate radical is essentially irreversible. Global fitting of these data allows estimation of the intrinsic rate constants associated with CoC homolysis and initial H-abstraction steps. In contrast to previous stopped-flow studies, the apparent kinetic isotope effects are found to be relatively small.
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Affiliation(s)
- Alex R Jones
- School of Chemistry, Manchester Institute of Biotechnology and Photon Science Institute, The University of Manchester, Alan Turing Building, Oxford Road, Manchester M13 9PL (UK).
| | - Julius Rentergent
- Manchester Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN (UK)
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN (UK)
| | - Sam Hay
- Manchester Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN (UK).
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168
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Singh P, Francis K, Kohen A. Network of remote and local protein dynamics in dihydrofolate reductase catalysis. ACS Catal 2015; 5:3067-3073. [PMID: 27182453 DOI: 10.1021/acscatal.5b00331] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular dynamics calculations and bionformatic studies of dihydrofolate reductase (DHFR) have suggested a network of coupled motions across the whole protein that is correlated to the reaction coordinate. Experimental studies demonstrated that distal residues G121, M42 and F125 in E. coli DHFR participate in that network. The missing link in our understanding of DHFR catalysis is the lack of a mechanism by which such remote residues can affect the catalyzed chemistry at the active site. Here, we present a study of the temperature dependence of intrinsic kinetic isotope effects (KIEs) that indicates synergism between a remote residue in that dynamic network, G121, and the active site's residue I14. The intrinsic KIEs for the I14A-G121V double mutant showed steeper temperature dependence (ΔEa(T-H)) than expected from comparison of the wild type and two single mutants. That effect was non-additive, i.e., ΔEa(T-H)G121V +ΔEa(T-H) I14A < ΔEa(T-H) double mutant, which indicates a synergism between the two residues. This finding links the remote residues in the network under investigation to the enzyme's active site, providing a mechanism by which these residues can be coupled to the catalyzed chemistry. This experimental evidence validates calculations proposing that both remote and active site residues constitute a network of coupled promoting motions correlated to the bond activation step (C-H→C hydride transfer in this case). Additionally, the effect of I14A and G121V mutations on single turnover rates was additive rather than synergistic. Although single turnover rate measurements are more readily available and thus more popular than assessing intrinsic kinetic isotope effects, the current finding demonstrates that for these rates, which in DHFR reflect several microscopic rate constants, can fall short of revealing the nature of the C-H bond activation per se.
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Affiliation(s)
- Priyanka Singh
- The Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Kevin Francis
- The Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Amnon Kohen
- The Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
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169
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Singh P, Abeysinghe T, Kohen A. Linking protein motion to enzyme catalysis. Molecules 2015; 20:1192-209. [PMID: 25591120 PMCID: PMC4341894 DOI: 10.3390/molecules20011192] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Accepted: 01/07/2015] [Indexed: 12/01/2022] Open
Abstract
Enzyme motions on a broad range of time scales can play an important role in various intra- and intermolecular events, including substrate binding, catalysis of the chemical conversion, and product release. The relationship between protein motions and catalytic activity is of contemporary interest in enzymology. To understand the factors influencing the rates of enzyme-catalyzed reactions, the dynamics of the protein-solvent-ligand complex must be considered. The current review presents two case studies of enzymes—dihydrofolate reductase (DHFR) and thymidylate synthase (TSase)—and discusses the role of protein motions in their catalyzed reactions. Specifically, we will discuss the utility of kinetic isotope effects (KIEs) and their temperature dependence as tools in probing such phenomena.
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Affiliation(s)
- Priyanka Singh
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
| | - Thelma Abeysinghe
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
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