Sulfenic acids react as both nucleophiles and electrophiles, which may be attributable to interconversion between sulfenyl and sulfinyl tautomers. We demonstrate one-pot trapping of both tautomeric forms of glutathione sulfenic acid by LCMS. The sulfinyl tautomers are characterized by reaction with nucleophilic reagents such as dimedone and cyanide, giving unique products that are analogous to corresponding adducts of aldehydes. Likewise, we show that aldehyde reactive reagents such as silyl enol ethers also react with glutathione sulfenic acid to give products characteristic of both sulfenyl and sulfinyl tautomers.
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http://dx.doi.org/10.1021/acschembio.6b00980 | DOI Listing |
ACS Chem Biol
February 2017
Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States.
Sulfenic acids react as both nucleophiles and electrophiles, which may be attributable to interconversion between sulfenyl and sulfinyl tautomers. We demonstrate one-pot trapping of both tautomeric forms of glutathione sulfenic acid by LCMS. The sulfinyl tautomers are characterized by reaction with nucleophilic reagents such as dimedone and cyanide, giving unique products that are analogous to corresponding adducts of aldehydes.
View Article and Find Full Text PDFJ Phys Chem A
April 2015
Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States.
The conformations, equilibrium structures, hydrogen bonds, and non-covalent interactions involved in the mechanisms of tautomerization, condensations, and C-sulfenylation and O-sulfenylation of 2,4-pentanedione by sulfur hydride hydroxide (hydrogen thioperoxide, oxadisulfane, H-SOH) have been studied using BD(T), CCSD(T), and QCISD(T) with the cc-pVTZ basis set and using B3LYP, B3PW91, CAM-B3LYP, PBE1PBE, PBEh1PBE, LC-ωPBE, M06-2X, and ωB97XD with the 6-311+G(d,p) basis set. All levels of theory predict the sulfenyl (H-SOH) tautomer of hydrogen thioperoxide to be lower in energy than the sulfinyl (H2S═O) tautomer. Four reasonable mechanisms were considered for the tautomerization of the sulfenyl tautomer of hydrogen thioperoxide to the sulfinyl tautomer: a cyclic three-membered water-free transition state (TS, CCSD(T) activation energy barrier E(⧧) = 65.
View Article and Find Full Text PDFJ Phys Chem A
April 2011
Department of Chemistry and Biochemistry and Centre for Research in Molecular Modeling, Concordia University, 7141 Sherbrooke Street West, Montreal, QC H4B 1R6, Canada.
We present a computational study on the concerted hydrolysis of several classes of N-sulfinylamines of generic formula R-N═S═O, such as the -amines themselves (R-NSO), -hydrazines (R-NH-NSO), -hydrazides (R-CO-NH-NSO) and -amides (R-CO-NSO), as these species are known to possess a wide range of hydrolytic reactivity. Two possible mechanisms of hydrolysis, with a water dimer across the S═O and N═S bonds, in the gas phase are investigated. The reactivity is discussed with respect to the electronic structures, established with the use of the quantum theory of Atoms in Molecules, Natural Bond Orbital and Natural Resonance Theory approaches.
View Article and Find Full Text PDFChirality
October 2010
Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel.
The pyramidal inversion mechanisms of the 6-methoxy and the 5-methoxy tautomers of (S)-omeprazole were studied, employing ab initio and DFT methods. The conformational space of the model molecule (S)-2-[(3-methyl-2-pyridinyl)methyl]sulfinyl-1H-benzimidazole was calculated, with respect to rotations around single bonds, at the B3LYP/6-311G(d,p) level. All of the resulting conformations were used as starting points for full optimizations of (S)-omeprazole, at B3LYP/6-31G(d), B3LYP/6-311G(d,p), B3LYP/6-311++G(d,p), B3LYP/6-311G(2df,2pd), MP2/6-31G(d), and MP2/6-311G(d,p) levels.
View Article and Find Full Text PDFChirality
January 2006
Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel.
A study of the conformational spaces of the chiral proton pump inhibitor (PPI) drug omeprazole by semiempirical, ab-initio, and DFT methods is described. In addition to the chiral center at the sulfinyl sulfur atom, the chiral axis at the pyridine ring (due to the hindered rotation of the 4-methoxy substituents) was considered. The results were analyzed in terms of the 5-methoxy and 6-methoxy tautomers and the two pairs of enantiomers (R,P)/(S,M) and (R,M)/(S,P).
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