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Mechanisms and consequences of protein cysteine oxidation: the role of the initial short-lived intermediates. Essays Biochem 2020; 64:55-66. [PMID: 31919496 DOI: 10.1042/ebc20190053] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 12/27/2022]
Abstract
Thiol groups in protein cysteine (Cys) residues can undergo one- and two-electron oxidation reactions leading to the formation of thiyl radicals or sulfenic acids, respectively. In this mini-review we summarize the mechanisms and kinetics of the formation of these species by biologically relevant oxidants. Most of the latter react with the deprotonated form of the thiol. Since the pKa of the thiols in protein cysteines are usually close to physiological pH, the thermodynamics and the kinetics of their oxidation in vivo are affected by the acidity of the thiol. Moreover, the protein microenvironment has pronounced effects on cysteine residue reactivity, which in the case of the oxidation mediated by hydroperoxides, is known to confer specificity to particular protein cysteines. Despite their elusive nature, both thiyl radicals and sulfenic acids are involved in the catalytic mechanism of several enzymes and in the redox regulation of protein function and/or signaling pathways. They are usually short-lived species that undergo further reactions that converge in the formation of different stable products, resulting in several post-translational modifications of the protein. Some of these can be reversed through the action of specific cellular reduction systems. Others damage the proteins irreversibly, and can make them more prone to aggregation or degradation.
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Saif B, Zhang W, Zhang X, Gu Q, Yang P. Sn-Triggered Two-Dimensional Fast Protein Assembly with Emergent Functions. ACS NANO 2019; 13:7736-7749. [PMID: 31244042 DOI: 10.1021/acsnano.9b01392] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The discovery of a general strategy for organizing functional proteins into stable nanostructures with the desired dimension, shape, and function is an important focus in developing protein-based self-assembled materials, but the scalable synthesis of such materials and transfer to other substrates remain great challenges. We herein tackle this issue by creating a two-dimensional metal-protein hybrid nanofilm that is flexible and cost-effective with reliable self-recovery, stability, and multifunctionality. As it differs from traditional metal ions, we discover the capability of Sn2+ to initiate fast amyloid-like protein assembly (occurring in seconds) by effectively reducing the disulfide bonds of native globular proteins. The Sn2+-initiated lysozyme aggregation at the air/water interface leads to droplet flattening, a result never before reported in a protein system, which finally affords a multifunctional 2D Sn-doped hybrid lysozyme nanofilm with an ultralarge area (e.g., 0.2 m2) within a few minutes. The hybrid film is distinctive in its ease of coating on versatile material surfaces with endurable chemical and mechanical stability, optical transparency, and diverse end uses in antimicrobial and photo-/electrocatalytic scaffolds. Our approach provides not only insights into the effect of tin ions on macroscopic self-assembly of proteins but also a controllable and scalable synthesis of a potential biomimic framework for biomedical and biocatalytic applications.
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Affiliation(s)
- Bassam Saif
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710062 , P.R. China
| | - Wenxin Zhang
- School and Hospital of Stomatology , Tianjin Medical University , 12 Observatory Road , Tianjin 30070 , P.R. China
| | - Xu Zhang
- School and Hospital of Stomatology , Tianjin Medical University , 12 Observatory Road , Tianjin 30070 , P.R. China
| | - Quan Gu
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710062 , P.R. China
| | - Peng Yang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710062 , P.R. China
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Bunik VI. Redox-Driven Signaling: 2-Oxo Acid Dehydrogenase Complexes as Sensors and Transmitters of Metabolic Imbalance. Antioxid Redox Signal 2019; 30:1911-1947. [PMID: 30187773 DOI: 10.1089/ars.2017.7311] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
SIGNIFICANCE This article develops a holistic view on production of reactive oxygen species (ROS) by 2-oxo acid dehydrogenase complexes. Recent Advances: Catalytic and structural properties of the complexes and their components evolved to minimize damaging effects of side reactions, including ROS generation, simultaneously exploiting the reactions for homeostatic signaling. CRITICAL ISSUES Side reactions of the complexes, characterized in vitro, are analyzed in view of protein interactions and conditions in vivo. Quantitative data support prevalence of the forward 2-oxo acid oxidation over the backward NADH oxidation in feeding physiologically significant ROS production by the complexes. Special focus on interactions between the active sites within 2-oxo acid dehydrogenase complexes highlights the central relevance of the complex-bound thiyl radicals in regulation of and signaling by complex-generated ROS. The thiyl radicals arise when dihydrolipoyl residues of the complexes regenerate FADH2 from the flavin semiquinone coproduced with superoxide anion radical in 1e- oxidation of FADH2 by molecular oxygen. FUTURE DIRECTIONS Interaction of 2-oxo acid dehydrogenase complexes with thioredoxins (TRXs), peroxiredoxins, and glutaredoxins mediates scavenging of the thiyl radicals and ROS generated by the complexes, underlying signaling of disproportional availability of 2-oxo acids, CoA, and NAD+ in key metabolic branch points through thiol/disulfide exchange and medically important hypoxia-inducible factor, mammalian target of rapamycin (mTOR), poly (ADP-ribose) polymerase, and sirtuins. High reactivity of the coproduced ROS and thiyl radicals to iron/sulfur clusters and nitric oxide, peroxynitrite reductase activity of peroxiredoxins and transnitrosylating function of thioredoxin, implicate the side reactions of 2-oxo acid dehydrogenase complexes in nitric oxide-dependent signaling and damage.
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Affiliation(s)
- Victoria I Bunik
- 1 Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation.,2 Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
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Trujillo M, Alvarez B, Radi R. One- and two-electron oxidation of thiols: mechanisms, kinetics and biological fates. Free Radic Res 2015; 50:150-71. [PMID: 26329537 DOI: 10.3109/10715762.2015.1089988] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The oxidation of biothiols participates not only in the defense against oxidative damage but also in enzymatic catalytic mechanisms and signal transduction processes. Thiols are versatile reductants that react with oxidizing species by one- and two-electron mechanisms, leading to thiyl radicals and sulfenic acids, respectively. These intermediates, depending on the conditions, participate in further reactions that converge on different stable products. Through this review, we will describe the biologically relevant species that are able to perform these oxidations and we will analyze the mechanisms and kinetics of the one- and two-electron reactions. The processes undergone by typical low-molecular-weight thiols as well as the particularities of specific thiol proteins will be described, including the molecular determinants proposed to account for the extraordinary reactivities of peroxidatic thiols. Finally, the main fates of the thiyl radical and sulfenic acid intermediates will be summarized.
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Affiliation(s)
- Madia Trujillo
- a Departamento de Bioquímica , Facultad de Medicina, Universidad de la República , Montevideo , Uruguay .,b Center for Free Radical and Biomedical Research , Universidad de la República , Montevideo , Uruguay , and
| | - Beatriz Alvarez
- b Center for Free Radical and Biomedical Research , Universidad de la República , Montevideo , Uruguay , and.,c Laboratorio de Enzimología, Facultad de Ciencias , Universidad de la República , Montevideo , Uruguay
| | - Rafael Radi
- a Departamento de Bioquímica , Facultad de Medicina, Universidad de la República , Montevideo , Uruguay .,b Center for Free Radical and Biomedical Research , Universidad de la República , Montevideo , Uruguay , and
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Nakajima M, Fava E, Loescher S, Jiang Z, Rueping M. Photoredox-Catalyzed Reductive Coupling of Aldehydes, Ketones, and Imines with Visible Light. Angew Chem Int Ed Engl 2015; 54:8828-32. [DOI: 10.1002/anie.201501556] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Indexed: 11/09/2022]
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Nakajima M, Fava E, Loescher S, Jiang Z, Rueping M. Eine additivarme photoredoxkatalysierte reduktive Kupplung von Aldehyden, Ketonen und Iminen mit sichtbarem Licht. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201501556] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Höckendorf RF, Hao Q, Sun Z, Fox-Beyer BS, Cao Y, Balaj OP, Bondybey VE, Siu CK, Beyer MK. Reactions of CH3SH and CH3SSCH3 with gas-phase hydrated radical anions (H2O)n(•-), CO2(•-)(H2O)n, and O2(•-)(H2O)n. J Phys Chem A 2012; 116:3824-35. [PMID: 22435875 DOI: 10.1021/jp302076f] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The chemistry of (H(2)O)(n)(•-), CO(2)(•-)(H(2)O)(n), and O(2)(•-)(H(2)O)(n) with small sulfur-containing molecules was studied in the gas phase by Fourier transform ion cyclotron resonance mass spectrometry. With hydrated electrons and hydrated carbon dioxide radical anions, two reactions with relevance for biological radiation damage were observed, cleavage of the disulfide bond of CH(3)SSCH(3) and activation of the thiol group of CH(3)SH. No reactions were observed with CH(3)SCH(3). The hydrated superoxide radical anion, usually viewed as major source of oxidative stress, did not react with any of the compounds. Nanocalorimetry and quantum chemical calculations give a consistent picture of the reaction mechanism. The results indicate that the conversion of e(-) and CO(2)(•-) to O(2)(•-) deactivates highly reactive species and may actually reduce oxidative stress. For reactions of (H(2)O)(n)(•-) with CH(3)SH as well as CO(2)(•-)(H(2)O)(n) with CH(3)SSCH(3), the reaction products in the gas phase are different from those reported in the literature from pulse radiolysis studies. This observation is rationalized with the reduced cage effect in reactions of gas-phase clusters.
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Affiliation(s)
- Robert F Höckendorf
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, 24098 Kiel, Germany
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Mechanical force can fine-tune redox potentials of disulfide bonds. Biophys J 2012; 102:622-9. [PMID: 22325286 DOI: 10.1016/j.bpj.2011.12.039] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 12/16/2011] [Indexed: 11/20/2022] Open
Abstract
Mechanical force applied along a disulfide bond alters its rate of reduction. We here aimed at quantifying the direct effect of force onto the chemical reactivity of a sulfur-sulfur bond in contrast to indirect, e.g., steric or mechanistic, influences. To this end, we evaluated the dependency of a disulfide bond's redox potential on a pulling force applied along the system. Our QM/MM simulations of cystine as a model system take conformational dynamics and explicit solvation into account and show that redox potentials increase over the whole range of forces probed here (30-3320 pN), and thus even in the absence of a significant disulfide bond elongation (<500 pN). Instead, at low forces, dihedrals and angles, as the softer degrees of freedom are stretched, contribute to the destabilization of the oxidized state. We find physiological forces to be likely to tune the disulfide's redox potentials to an extent similar to the tuning within proteins by point mutations.
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Metabolic control exerted by the 2-oxoglutarate dehydrogenase reaction: a cross-kingdom comparison of the crossroad between energy production and nitrogen assimilation. Biochem J 2009; 422:405-21. [PMID: 19698086 DOI: 10.1042/bj20090722] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mechanism-based inhibitors and both forward and reverse genetics have proved to be essential tools in revealing roles for specific enzymatic processes in cellular function. Here, we review experimental studies aimed at assessing the impact of OG (2-oxoglutarate) oxidative decarboxylation on basic cellular activities in a number of biological systems. After summarizing the catalytic and regulatory properties of the OGDHC (OG dehydrogenase complex), we describe the evidence that has been accrued on its cellular role. We demonstrate an essential role of this enzyme in metabolic control in a wide range of organisms. Targeting this enzyme in different cells and tissues, mainly by its specific inhibitors, effects changes in a number of basic functions, such as mitochondrial potential, tissue respiration, ROS (reactive oxygen species) production, nitrogen metabolism, glutamate signalling and survival, supporting the notion that the evolutionary conserved reaction of OG degradation is required for metabolic adaptation. In particular, regulation of OGDHC under stress conditions may be essential to overcome glutamate excitotoxicity in neurons or affect the wound response in plants. Thus, apart from its role in producing energy, the flux through OGDHC significantly affects nitrogen assimilation and amino acid metabolism, whereas the side reactions of OGDHC, such as ROS production and the carboligase reaction, have biological functions in signalling and glyoxylate utilization. Our current view on the role of OGDHC reaction in various processes within complex biological systems allows us a far greater fundamental understanding of metabolic regulation and also opens up new opportunities for us to address both biotechnological and medical challenges.
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Houée-Levin C, Bergès J. Single electron localisation on the cystine/cysteine couple: sulphur or carbon? RESEARCH ON CHEMICAL INTERMEDIATES 2009. [DOI: 10.1007/s11164-009-0041-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Houée-Levin C, Bergès J. Conformational stability of disulfide bonds in redox processes. Radiat Phys Chem Oxf Engl 1993 2008. [DOI: 10.1016/j.radphyschem.2008.05.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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12
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Bergès J, Rickard G, Rauk A, Houée-Levin C. Proton distribution in one-electron reduced thioredoxin modulated by aspartate 30: A QM/MM study. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.01.076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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13
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Fourré I, Silvi B. What can we learn from two-center three-electron bonding with the topological analysis of ELF? HETEROATOM CHEMISTRY 2007. [DOI: 10.1002/hc.20325] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Modelli A, Jones D. Temporary Anion States and Dissociative Electron Attachment in Diphenyl Disulfide. J Phys Chem A 2006; 110:10219-24. [PMID: 16928111 DOI: 10.1021/jp0628683] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The temporary anion states of gas-phase diphenyl disulfide are characterized by means of electron transmission (ET) and dissociative electron attachment (DEA) spectroscopies. The measured energies of vertical electron attachment are compared to the virtual orbital energies of the neutral state molecule supplied by MP2 and B3LYP calculations with the 6-31G basis set. The calculated energies, scaled with empirical equations, reproduce satisfactorily the attachment energies measured in the ET spectrum. The first anion state of diphenyl disulfide is stable, thus escaping detection in ETS. The vertical and adiabatic electron affinities, evaluated with B3LYP/6-31+G calculations as the energy difference between the neutral and anion states, are predicted to be 0.37 and 1.38 eV, respectively. The anion current displayed in the DEA spectrum has a sharp and intense peak at zero energy, essentially due to the C6H5S- negative fragment. In agreement, according to the calculations, the localization properties of the first anion state are strongly S-S antibonding, and the energetic requirement for its dissociation along the S-S bond is fulfilled even at zero energy.
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Affiliation(s)
- Alberto Modelli
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, via Selmi 2, 40126 Bologna, Italy.
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Sicard-Roselli C, Lemaire S, Jacquot JP, Favaudon V, Marchand C, Houée-Levin C. Thioredoxin Ch1 of Chlamydomonas reinhardtii displays an unusual resistance toward one-electron oxidation. ACTA ACUST UNITED AC 2004; 271:3481-7. [PMID: 15317583 DOI: 10.1111/j.1432-1033.2004.04279.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
To test thioredoxin resistance to oxidizing free radicals, we have studied the one-electron oxidation of wild-type thioredoxin and of two forms with the point mutations D30A and W35A, using azide radicals generated by gamma-ray or pulse radiolysis. The oxidation patterns of wild-type thioredoxin and D30A are similar. In these forms, Trp35 is the primary target and is 'repaired' by one-electron reduction; first by intramolecular electron transfer from tyrosine, and then from other residues. Conversely, during oxidation of W35A, Trp13 is poorly reactive. For all proteins, activity is conserved showing an unusual resistance toward oxidation.
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Sawicka A, Skurski P, Simons J. Excess Electron Attachment to Disulfide-Bridged l,l-Cystine. An ab Initio Study. J Phys Chem A 2004. [DOI: 10.1021/jp0311862] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Agnieszka Sawicka
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80−952 Gdańsk, Poland, and Henry Eyring Center for Theoretical Chemistry, Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Piotr Skurski
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80−952 Gdańsk, Poland, and Henry Eyring Center for Theoretical Chemistry, Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Jack Simons
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80−952 Gdańsk, Poland, and Henry Eyring Center for Theoretical Chemistry, Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
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18
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Probing the stability of the disulfide radical intermediate of thioredoxin using direct electrochemistry. Int J Pept Res Ther 2003. [DOI: 10.1007/s10989-004-2410-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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19
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Probing the stability of the disulfide radical intermediate of thioredoxin using direct electrochemistry. ACTA ACUST UNITED AC 2003. [DOI: 10.1007/bf02442581] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Braïda B, Hiberty PC. A Simplified Gaussian-2 Scheme for Determining Electron Affinities of Covalent Bonds. Application to the Disulfide Bond RS−SR‘ (R, R‘ = H, CH3, C2H5). J Phys Chem A 2003. [DOI: 10.1021/jp0341624] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Benoît Braïda
- Laboratoire de Chimie physique, Groupe de Chimie Théorique, Bat 490, Université de Paris-Sud, 91405 Orsay Cédex, France
| | - Philippe C. Hiberty
- Laboratoire de Chimie physique, Groupe de Chimie Théorique, Bat 490, Université de Paris-Sud, 91405 Orsay Cédex, France
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Abstract
A number of cellular systems cooperate in redox regulation, providing metabolic responses according to changes in the oxidation (or reduction) of the redox active components of a cell. Key systems of central metabolism, such as the 2-oxo acid dehydrogenase complexes, are important participants in redox regulation, because their function is controlled by the NADH/NAD+ ratio and the complex-bound dihydrolipoate/lipoate ratio. Redox state of the complex-bound lipoate is an indicator of the availability of the reaction substrates (2-oxo acid, CoA and NAD+) and thiol-disulfide status of the medium. Accumulation of the dihydrolipoate intermediate causes inactivation of the first enzyme of the complexes. With the mammalian pyruvate dehydrogenase, the phosphorylation system is involved in the lipoate-dependent regulation, whereas mammalian 2-oxoglutarate dehydrogenase exhibits a higher sensitivity to direct regulation by the complex-bound dihydrolipoate/lipoate and external SH/S-S, including mitochondrial thioredoxin. Thioredoxin efficiently protects the complexes from self-inactivation during catalysis at low NAD+. As a result, 2-oxoglutarate dehydrogenase complex may provide succinyl-CoA for phosphorylation of GDP and ADP under conditions of restricted NAD+ availability. This may be essential upon accumulation of NADH and exhaustion of the pyridine nucleotide pool. Concomitantly, thioredoxin stimulates the complex-bound dihydrolipoate-dependent production of reactive oxygen species. It is suggested that this side-effect of the 2-oxo acid oxidation at low NAD+in vivo would be overcome by cooperation of mitochondrial thioredoxin and the thioredoxin-dependent peroxidase, SP-22.
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Affiliation(s)
- Victoria I Bunik
- A.N.Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
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Bunik VI, Sievers C. Inactivation of the 2-oxo acid dehydrogenase complexes upon generation of intrinsic radical species. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:5004-15. [PMID: 12383259 DOI: 10.1046/j.1432-1033.2002.03204.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Self-regulation of the 2-oxo acid dehydrogenase complexes during catalysis was studied. Radical species as side products of catalysis were detected by spin trapping, lucigenin fluorescence and ferricytochrome c reduction. Studies of the complexes after converting the bound lipoate or FAD cofactors to nonfunctional derivatives indicated that radicals are generated via FAD. In the presence of oxygen, the 2-oxo acid, CoA-dependent production of the superoxide anion radical was detected. In the absence of oxygen, a protein-bound radical concluded to be the thiyl radical of the complex-bound dihydrolipoate was trapped by alpha-phenyl-N-tert-butylnitrone. Another, carbon-centered, radical was trapped in anaerobic reaction of the complex with 2-oxoglutarate and CoA by 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO). Generation of radical species was accompanied by the enzyme inactivation. A superoxide scavenger, superoxide dismutase, did not protect the enzyme. However, a thiyl radical scavenger, thioredoxin, prevented the inactivation. It was concluded that the thiyl radical of the complex-bound dihydrolipoate induces the inactivation by 1e- oxidation of the 2-oxo acid dehydrogenase catalytic intermediate. A product of this oxidation, the DMPO-trapped radical fragment of the 2-oxo acid substrate, inactivates the first component of the complex. The inactivation prevents transformation of the 2-oxo acids in the absence of terminal substrate, NAD+. The self-regulation is modulated by thioredoxin which alleviates the adverse effect of the dihydrolipoate intermediate, thus stimulating production of reactive oxygen species by the complexes. The data point to a dual pro-oxidant action of the complex-bound dihydrolipoate, propagated through the first and third component enzymes and controlled by thioredoxin and the (NAD+ + NADH) pool.
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Affiliation(s)
- Victoria I Bunik
- A.N.Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.
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Braïda B, Thogersen L, Wu W, Hiberty PC. Stability, Metastability, and Unstability of Three-Electron-Bonded Radical Anions. A Model ab Initio Theoretical Study. J Am Chem Soc 2002; 124:11781-90. [PMID: 12296746 DOI: 10.1021/ja026707y] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The stability of O therefore O, N therefore N, S therefore S, P therefore P, and Si therefore Si three-electron bonds in anionic radicals isoelectronic to dihalogen radical anions is studied by means of ab initio calculations on model systems. The difficulty of generating the dissociation energy profiles of such anions and their rearrangement to neutral species is solved by a practical method which consists of calculating the neutral and anionic energy profiles separately and shifting the curves with respect to each other to match the experimental energy gap between the asymptotes. Here the neutral and anionic reaction profiles are calculated at the CASPT2 and MP2 levels, respectively. The calculations predict that the O therefore O bond is likely to be observed in anions of the type [RO therefore OR](*-), where R is any alkyl substituent or carbon chain. The anion Si(2)H(6)(*-) is found to be a metastable species, with a fair barrier to electron detachment. The barrier is much smaller for N(2)H(4)(*-) and P(2)H(4)(*-), thus precluding experimental observation. However, these species can be stabilized by electron-attractor substituents, the effect of which can be quantitatively estimated by means of the parent anion's diagrams and some fast complementary calculations. An example is given with the [CF(3)HN therefore NHCF(3)](*-) anionic complex.
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Affiliation(s)
- Benoît Braïda
- Laboratoire de Chimie Physique, Groupe de Chimie Théorique, Bat 490, Université de Paris-Sud, 91405 ORSAY Cédex, France
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Houée-Levin C. Determination of redox properties of protein disulfide bonds by radiolytic methods. Methods Enzymol 2002; 353:35-44. [PMID: 12078509 DOI: 10.1016/s0076-6879(02)53034-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- Chantal Houée-Levin
- Laboratory of Physical Chemistry, Interdisciplinary Research Laboratory 8000, Centre Universitaire, F-91405 Orsay, France
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Braïda B, Hazebroucq S, Hiberty PC. Methyl substituent effects in [H(n)X...XH(n)](+) three-electron-bonded radical cations (X = F, O, N, Cl, S, P; n = 1 - 3). An ab initio theoretical study. J Am Chem Soc 2002; 124:2371-8. [PMID: 11878994 DOI: 10.1021/ja0165887] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of methyl substitution on the geometries and bonding energies of a systematic series of three-electron-bonded radical cations of the type [H(n)X...XH(n)](+), covering all possible symmetrical three-electron bonds that may take place between atoms of the second and third rows of the periodic table, have been investigated at the level of Møller-Plesset perturbation theory. Methyl substitution leads to significant weakening and lengthening of the X...X bond when X is a second-row atom. The effects increase with the number of substitutions and are more and more important in the series X = N, O, F. By contrast, methyl substitution leaves the bonding energies between third-row atoms practically unchanged but leads to a surprising bond shortening in the S...S and P...P cases. These seemingly contradictory effects are rationalized through a qualitative analysis based on an elementary molecular orbital description of three-electron bonding.
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Affiliation(s)
- Benoît Braïda
- Laboratoire de Chimie-Physique, Groupe de Chimie Théorique, Université de Paris-Sud, 91405 Orsay Cedex, France
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26
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Menchise V, Corbier C, Didierjean C, Jacquot JP, Benedetti E, Saviano M, Aubry A. Crystal structure of the W35A mutant thioredoxin h from Chlamydomonas reinhardtii: the substitution of the conserved active site Trp leads to modifications in the environment of the two catalytic cysteines. Biopolymers 2002; 56:1-7. [PMID: 11582571 DOI: 10.1002/1097-0282(2000)56:1<1::aid-bip1036>3.0.co;2-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The conformational analysis of W35A thioredoxin h from the eukaryotic green alga Chlamydomonas reinhardtii in the solid state has been carried out by x-ray diffraction, with the aim to clarify the role of Trp in the catalysis. Comparative analysis of W35A mutant with wild-type (WT) thioredoxin shows that, even if the structural motif of thioredoxin is not perturbed, the substitution of Trp35 by an Ala leads to significant changes in protein conformation near the active site. This rearrangement increases its solvent exposure and explains the change of the pKa values of the catalytic cysteines. The substitution of the Trp residue also influences the crystal packing as well as the recognition ability of thioredoxin. The solid state analysis suggests that the Trp residue has a structural function both to force the active site in the bioactive conformation, and to mediate the protein-protein recognition.
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Affiliation(s)
- V Menchise
- LCM3B, groupe Biocristallographie, ESA CNRS 7036, Université Henri Poincaré, Nancy 1, Faculté des Sciences, BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France
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27
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Weik M, Ravelli RB, Silman I, Sussman JL, Gros P, Kroon J. Specific protein dynamics near the solvent glass transition assayed by radiation-induced structural changes. Protein Sci 2001; 10:1953-61. [PMID: 11567086 PMCID: PMC2374210 DOI: 10.1110/ps.09801] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2001] [Revised: 06/22/2001] [Accepted: 07/03/2001] [Indexed: 10/17/2022]
Abstract
The nature of the dynamical coupling between a protein and its surrounding solvent is an important, yet open issue. Here we used temperature-dependent protein crystallography to study structural alterations that arise in the enzyme acetylcholinesterase upon X-ray irradiation at two temperatures: below and above the glass transition of the crystal solvent. A buried disulfide bond, a buried cysteine, and solvent exposed methionine residues show drastically increased radiation damage at 155 K, in comparison to 100 K. Additionally, the irradiation-induced unit cell volume increase is linear at 100 K, but not at 155 K, which is attributed to the increased solvent mobility at 155 K. Most importantly, we observed conformational changes in the catalytic triad at the active site at 155 K but not at 100 K. These changes lead to an inactive catalytic triad conformation and represent, therefore, the observation of radiation-inactivation of an enzyme at the atomic level. Our results show that at 155 K, the protein has acquired--at least locally--sufficient conformational flexibility to adapt to irradiation-induced alterations in the conformational energy landscape. The increased protein flexibility may be a direct consequence of the solvent glass transition, which expresses as dynamical changes in the enzyme's environment. Our results reveal the importance of protein and solvent dynamics in specific radiation damage to biological macromolecules, which in turn can serve as a tool to study protein flexibility and its relation to changes in a protein's environment.
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Affiliation(s)
- M Weik
- Department of Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands.
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28
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Carles S, Lecomte F, Schermann JP, Desfrançois C, Xu S, Nilles JM, Bowen KH, Bergès J, Houée-Levin C. Nondissociative Electron Capture by Disulfide Bonds. J Phys Chem A 2001. [DOI: 10.1021/jp0040603] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | | | | | | | | | | | | | - J. Bergès
- Laboratoire de Chimie Théorique, UMR 7616 CNRS - Université Paris 6, 75005 Paris, France
| | - C. Houée-Levin
- Laboratoire de Chimie Physique, UMR 8600 CNRS - Université Paris-Sud, 91405 Orsay, France
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