Chemistry of sulfenic acids. 7. Reason for the high reactivity of sulfenic acids. Stabilization by intramolecular hydrogen bonding and electronegativity effects

Davis, Franklin A.; Jenkins, Linda A.; Billmers, Robert L.

doi:10.1021/jo00357a017

Cited by 113 publications

(52 citation statements)

References 5 publications

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“…Two additional products having accurate mass values and adducts consistent with empirical formulae C 4 H 9 NO 3 S and C 4 H 8 O 4 S were identified by LC-TOFMS. Although these formulae are compatible with structures such as the previously unreported homocysteine sulphenic acid and 2-hydroxy-4-sulphenobutanoic acid; sulphenic acids are normally found to be highly reactive transient compounds that are difficult to detect and isolate unless stabilized by steric hindrance 44 or intramolecular H-bonding involving a seven-membered ring 45 . However, in view of the known instability of most sulphenic acids 44 , much stronger evidence will be required before the structures for the minor products can be confirmed and thus they are not shown as decay products in Fig.…”

Section: Resultsmentioning

confidence: 66%

Abiotic methanogenesis from organosulphur compounds under ambient conditions

et al. 2014

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Methane in the environment is produced by both biotic and abiotic processes. Biomethanation involves the formation of methane by microbes that live in oxygen-free environments. Abiotic methane formation proceeds under conditions at elevated temperature and/or pressure. Here we present a chemical reaction that readily forms methane from organosulphur compounds under highly oxidative conditions at ambient atmospheric pressure and temperature. When using iron(II/III), hydrogen peroxide and ascorbic acid as reagents, S-methyl groups of organosulphur compounds are efficiently converted into methane. In a first step, methyl sulphides are oxidized to the corresponding sulphoxides. In the next step, demethylation of the sulphoxide via homolytic bond cleavage leads to methyl radical formation and finally to methane in high yields. Because sulphoxidation of methyl sulphides is ubiquitous in the environment, this novel chemical route might mimic methane formation in living aerobic organisms.

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Section: Resultsmentioning

confidence: 66%

Abiotic methanogenesis from organosulphur compounds under ambient conditions

et al. 2014

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“…We speculate this was an intermediate state during the H 2 O 2 oxidation. H 2 O 2 is known to oxidize thiol groups to the highly reactive sulfenic acid (26). The most common reaction of sulfenic acids is the formation of thiosulfinate, if the two sulfenic acids are in close proximity within the protein (26).…”

Section: Discussionmentioning

confidence: 99%

“…H 2 O 2 is known to oxidize thiol groups to the highly reactive sulfenic acid (26). The most common reaction of sulfenic acids is the formation of thiosulfinate, if the two sulfenic acids are in close proximity within the protein (26). Sulfenic acid formation was thought to be vital for the activation of OxyR, a procaryotic transcription factor known to be activated by H 2 O 2 (27 contained a disulfide bond.…”

Section: Discussionmentioning

confidence: 99%

Mass Spectrometry Unravels Disulfide Bond Formation as the Mechanism That Activates a Molecular Chaperone

Barbirz¹,

Jakob²,

Glocker³

2000

Journal of Biological Chemistry

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The heat shock protein Hsp33 is a very potent molecular chaperone with a distinctive mode of functional regulation; its activity is redox-regulated. In its reduced form all six cysteinyl residues of Hsp33 are present as thiols, and Hsp33 displays no folding helper activity. This indicates a significant conformational change during the activation process of Hsp33. Mass spectrometry, thus, unraveled a novel molecular mechanism by which alteration of the disulfide bond structure, as a result of changes in the cellular redox potential, results in the activation of a molecular chaperone.Hsp33 is a newly discovered heat shock protein that functions as a highly efficient molecular chaperone (1). Hsp33 protects bacterial cells from deleterious effects caused by oxidants like H 2 O 2 showing that it plays a role in the bacterial defense system against oxidative stress. Hsp33 is distinguished from all other known chaperone proteins by the finding that Hsp33 is functionally regulated at posttranslational level, by the redox conditions of the environment (1) (reviewed in Refs. 2 and 3). Elevated H 2 O 2 concentrations induce the chaperone functions of Hsp33 (1), but the precise molecular mechanism that translates the changes of the cellular redox environment into differences in chaperone activity is not yet understood.The Hsp33 amino acid sequence contains a novel conserved motif consisting of four cysteinyl residues near the C terminus of the protein. These cysteinyl residues form a C-X-C motif and a C-Y-Z-C motif (Fig. 1), separated by 27-30 amino acid residues in Escherichia coli Hsp33 and its homologues. These four cysteinyl residues are present in all 27 known Hsp33 homologues suggesting that they play an important role in the function of Hsp33. In addition, two further cysteinyl residues, Cys 141 and Cys 239 , are present in Hsp33. Cys 239 is very poorly conserved occurring in only 4 of the 27 known Hsp33 homologues. Cys 141 is moderately conserved and is present in 10 of the 27 Hsp33 homologues known so far. We have postulated that disulfide bond formation is involved in the activation process of Hsp33. Thus, analysis of the disulfide bond status and connectivities in inactive and in active Hsp33 seemed very important to further understand the regulation of this efficient molecular chaperone.Two complementary mass spectrometry-based strategies are suitable for determining the presence and locations of disulfide bonds in proteins. Which one is superior is dependent on the proximity of the involved cysteinyl residues in the amino acid sequence. Both approaches involve cleavage of the protein by enzymatic or chemical means under conditions that minimize disulfide bond scrambling (4 -6). The first approach can be used when the proteolytically derived peptides contain zero or one cysteinyl residue. The peptide mixtures are directly analyzed by mass spectrometric peptide mapping. Molecular mass analyses identify the peptides and disulfide-bonded dipeptides by assigning the observed ion signals to the corresponding calculat...

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“…From the chemical point of view, RSOH exhibits both electrophilic and nucleophilic behavior. Thiosulfinate formation clearly exemplifies this dual nature (11), although this self-condensation has little biological relevance due to high abundant thiols and steric hindrance, which make this reaction negligible in cells. Therefore, oxidation to Cys-SO 2 H appears to be the only significant reaction in which RSOH exhibits its nucleophilic nature.…”

Section: Sulfenic Acid Formation and Reactivitymentioning

confidence: 96%