Structure-reactivity relations for thiol-disulfide interchange

Houk, Janette; Whitesides, George M.

doi:10.1021/ja00256a040

Cited by 229 publications

(141 citation statements)

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“…The fifth column of (13), it appears that our data are in conflict with the results obtained in earlier studies in which the indirect lipoamide dehydrogenase-mediated reaction system was used. This is especially perplexing because the lipoamide dehydrogenasemediated method appears to give more consistent results when applied to cyclic disulfide reagents (27). In addition, an experimental check on the value of the dithiothreitollipoamide equilibrium constant by determining the concentration of species by UV absorbance measurements (10) is in excellent agreement with the value obtained by the lipoamide dehydrogenase-mediated method (10).…”

mentioning

confidence: 71%

Equilibrium and kinetic constants for the thiol-disulfide interchange reaction between glutathione and dithiothreitol.

Rothwarf

Scheraga

1992

Proc. Natl. Acad. Sci. U.S.A.

106

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The equilibrium and rate constants for the reaction between oxidized and reduced glutathione and oxidized and reduced dithiothreitol have been determined at several pH values and temperatures. The measurements involve approach to equilibrium from both directions, quenching of the reaction by lowering the pH or by addition of methyl methanethiosulfonate, separation of reactants and products by reverse-phase HPLC, and determination of their concentrations. Analysis of reaction mixtures was carried out at various times to assure that equilibrium had been reached and to determine kinetic constants prior to the attainment of equilibrium.The thiol-disulfide interchange reaction is important in a variety of biological systems (1-3) and, in particular, in studies of the regeneration of disuffide-containing proteins from their reduced forms (4-6). The thiol/disulfide reagents in widest use in studies of the regeneration of proteins are oxidized glutathione (GSSG) and reduced glutathione (GSH), primarily because they are known to occur at significant concentrations in biological systems (7) and because they exhibit a suitable redox potential.The oxidation of monothiols such as GSH is a bimolecular process and is entropically different from the unimolecular process of disulfide formation that occurs in proteins. In contrast, the formation of cyclic disulfides such as oxidized dithiothreitol (DTToX) results from a unimolecular process. Glutathione forms stable mixed disulfides with protein thiols, which greatly complicates studies of regeneration pathways. On the other hand, while DTTOX is a much weaker oxidizing agent, it does not form stable mixed disulfides (because the cyclization reaction is very fast), making it a useful reagent for studies of protein regeneration (5, 8). It has been argued, though incorrectly, that, while these reagents differ in their entropies of disulfide formation, they are similar in their abilities to regenerate protein when concentrations are adjusted to give similar redox potentials (9).The role that these different types (mono-and cyclic thiol) of reagents play is a key feature of the detailed regeneration processes of proteins. Any attempt to distinguish these different roles requires a quantitative determination of their relative redox potentials. In order to make comparisons between the results of regeneration experiments using dithiothreitol and those using glutathione, it is necessary to know the equilibrium constant for the reaction between glutathione and dithiothreitol. The equations describing this equilibriumwhere the brackets indicate concentrations at equilibrium.Unfortunately, a wide range of values has been reported for this thiol-disulfide exchange equilibrium constant. Values of 8800 M at pH 7 and 300C (10) and 13,000 M at pH 7 and an unspecified temperature (11) have been reported, based on an indirect technique involving a lipoamide dehydrogenasemediated reaction between NAD+ and lipoamide. Use of intermediates populated during the regeneration of bovine pancreatic ...

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mentioning

confidence: 71%

Equilibrium and kinetic constants for the thiol-disulfide interchange reaction between glutathione and dithiothreitol.

Rothwarf

Scheraga

1992

Proc. Natl. Acad. Sci. U.S.A.

106

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“…It is interesting to note, however, that activity with 2-mercaptoethanol or glutathione is not observed (12,17). This lack of activity is presumably a consequence of decreased reducing power and the inability to form a more stable intermolecular ring structure like DTT or the formation of a stable disulfide bond in thioredoxin (36)(37)(38)(39)(40)(41).…”

Section: Discussionmentioning

confidence: 99%

Thiol–disulfide exchange is involved in the catalytic mechanism of peptide methionine sulfoxide reductase

Lowther

Brot

Weissbach

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

162

183

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Peptide methionine sulfoxide reductase (MsrA; EC 1.8.4.6) reverses the inactivation of many proteins due to the oxidation of critical methionine residues by reducing methionine sulfoxide, Met(O), to methionine. MsrA activity is independent of bound metal and cofactors but does require reducing equivalents from either DTT or a thioredoxin-regenerating system. In an effort to understand these observations, the four cysteine residues of bovine MsrA were mutated to serine in a series of permutations. An analysis of the enzymatic activity of the variants and their free sulfhydryl states by mass spectrometry revealed that thioldisulfide exchange occurs during catalysis. In particular, the strictly conserved Cys-72 was found to be essential for activity and could form disulfide bonds, only upon incubation with substrate, with either Cys-218 or Cys-227, located at the C terminus. The significantly decreased activity of the Cys-218 and Cys-227 variants in the presence of thioredoxin suggested that these residues shuttle reducing equivalents from thioredoxin to the active site. A reaction mechanism based on the known reactivities of thiols with sulfoxides and the available data for MsrA was formulated. In this scheme, Cys-72 acts as a nucleophile and attacks the sulfur atom of the sulfoxide moiety, leading to the formation of a covalent, tetracoordinate intermediate. Collapse of the intermediate is facilitated by proton transfer and the concomitant attack of Cys-218 on Cys-72, leading to the formation of a disulfide bond. The active site is returned to the reduced state for another round of catalysis by a series of thiol-disulfide exchange reactions via Cys-227, DTT, or thioredoxin.oxidation ͉ cysteine ͉ thioredoxin ͉ Alzheimer's disease ͉ aging

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“…The starting components of the network are cystamine (CSSC, 3) and L-alanine ethyl thioester (AlaSEt, 2). Trace amounts of cysteamine (CSH, 1) are generated as follows: AlaSEt slowly hydrolyzes, generating alanine (8) and ethanethiol (ESH, 4); EtSH then reacts with CSSC via thiolate-disulfide interchange, 24 yielding disulfide 6 and CSH. With CSH present, self-amplification occurs through two steps: (i) CSH reacts with AlaSEt rapidly by thiolate-thioester exchange and intramolecular rearrangement (Kent ligation), 25 yielding two thiols, EtSH, and L-alanine mercaptoethyl amide (5); and (ii) these two thiols then undergo thiolate-disulfide interchange with CSSC, yielding two molecules of CSH (and disulfides 6 and 7).…”

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confidence: 99%

Autocatalytic, bistable, oscillatory networks of biologically relevant organic reactions

Semenov

Kraft

Ainla

et al. 2016

Nature

Self Cite

308

274

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(ii) a trigger that controls autocatalytic growth; and (iii) inhibitory processes that remove activating thiol species produced during the autocatalytic cycle. In contrast to previous studies demonstrating oscillations and bistability using highly evolved biomolecules (i.e., enzymes 15 and DNA 16,17 ) or inorganic molecules of questionable biochemical relevance (e.g. those used in Belousov-Zhabotinsky-type reactions), 18,19 the organic molecules used in our network are relevant to current metabolism and similar to those that might have existed on early Earth. By using small organic molecules to build a network of organic reactions with autocatalytic, bistable, and oscillatory behavior, we identified principles that clarify how dynamic networks relevant to life might possibly have developed. In the future, modifications of this network will clarify the influence of molecular structure on the dynamics of reaction networks, and may enable the design of biomimetic networks, and of synthetic self-regulating and evolving chemical systems.3 Figure 1 summarizes the network of organic reactions that we used to assemble our model system. All of these reactions are nearly quantitative, and the structure of their reactants can be varied by synthesis to control rates of reactions. Thiols and thioesters, which are central to these reactions, are important in many biological processes (e.g., the formation of disulfide bonds in proteins, transformations involving coenzyme-A, the reduction of oxidized molecules by glutathione, 20 the synthesis of polyketides, 21 and the nonribosomal synthesis of peptides 21 ), and thus, might represent reactions that enabled life to emerge on early Earth. 22 To control the dynamics of these processes, we constructed a modular chemical reaction network (CRN) shown schematically in control-theoretic terms 23 in Fig. 1a. A "trigger" produces an initial chemical signal, and an "auto-amplifier" amplifies this signal, which may or may not be suppressed by inhibition. To keep the reactions out of equilibrium-and thus, to enable the self-organization of reactions by communication through concentrations of reactants and products -we used a continuous-stirred tank reactor (CSTR) to mix reactants and products, while allowing a flux of species into and out of the network over time. A biological cell has some conceptual analogies to a micron-scale, diffusively mixed, tank reactor. The dynamic behavior of this system -especially bistability and oscillationsreflects the balances of triggering, auto-amplification, and inhibition.We first constructed a chemical network capable of auto-amplification using thiols and thioesters (Fig. 1b). The starting components of the network are cystamine (CSSC, 3) and L-alanine ethyl thioester (AlaSEt, 2). Trace amounts of cysteamine (CSH, 1) are generated as follows: AlaSEt slowly hydrolyzes, generating alanine (8) and ethanethiol (ESH, 4); EtSH then reacts with CSSC via thiolate-disulfide interchange, 24 yielding disulfide 6 and CSH. With CSH present, self-amplification oc...

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Structure-reactivity relations for thiol-disulfide interchange

Cited by 229 publications

References 1 publication

Equilibrium and kinetic constants for the thiol-disulfide interchange reaction between glutathione and dithiothreitol.

Equilibrium and kinetic constants for the thiol-disulfide interchange reaction between glutathione and dithiothreitol.

Thiol–disulfide exchange is involved in the catalytic mechanism of peptide methionine sulfoxide reductase

Autocatalytic, bistable, oscillatory networks of biologically relevant organic reactions

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