ChemInform Abstract: Thermodynamic and Kinetic Studies of Reactions of Thiols, Disulfides, Sulfur, and Hydrogen Sulfide

ChemInform ◽  
2010 ◽  
Vol 31 (21) ◽  
pp. no-no
Author(s):  
Carl D. Hoff
Keyword(s):  
Hydrogen Sulfide ◽  
Kinetic Studies

scholarly journals Production of the Neuromodulator H2S by Cystathionine β-Synthase via the Condensation of Cysteine and Homocysteine

2004 ◽  
Vol 279 (50) ◽  
pp. 52082-52086 ◽  
Author(s):  
Xulin Chen ◽  
Kwang-Hwan Jhee ◽  
Warren D. Kruger
Keyword(s):  
Hydrogen Sulfide ◽  
Kinetic Studies ◽  
Mammalian Brain ◽  
Replacement Reaction ◽  
Elimination Kinetic ◽  
Major Mechanism ◽  
High Concentrations ◽  
Hydrolysis Of

Hydrogen sulfide (H2S) has been observed in relatively high concentrations in the mammalian brain and has been shown to act as a neuromodulator. However, there is confusion in the literature regarding the actual source of H2S production. Reactions catalyzed by the cystathionine β-synthase enzyme (CBS) are one possible source for the production of H2S. Here we show that the CBS enzyme can efficiently produce H2S via a β-replacement reaction in which cysteine is condensed with homocysteine to form cystathionine and H2S. The production of H2S by this reaction is at least 50 times more efficient than that produced by hydrolysis of cysteine alone via β-elimination. Kinetic studies demonstrate that theKmandKcatfor cysteine is 3-fold higher and 2-fold lower, respectively, than that for serine. Consistent with these data,in vitroreconstitution studies show that at physiologically relevant concentrations of serine, homocysteine, and cysteine, about 5% of the cystathionine formed is from cysteine. We also show that AdoMet stimulates this H2S producing reaction but that there is no evidence for stimulation by calcium and calmodulin as reported previously. In summary, these results confirm the ability of CBS to produce H2S, but show in contrast to prior reports that the major mechanism is via β-replacement and not cysteine hydrolysis. In addition, these studies provide a biochemical explanation for the previously inexplicable homocysteine-lowering effects ofN-acetylcysteine treatments in humans.

Kinetic studies of peroxiredoxin 6 from Arenicola marina: Rapid oxidation by hydrogen peroxide and peroxynitrite but lack of reduction by hydrogen sulfide

2011 ◽  
Vol 514 (1-2) ◽  
pp. 1-7 ◽  
Author(s):  
Eléonore Loumaye ◽  
Gerardo Ferrer-Sueta ◽  
Beatriz Alvarez ◽  
Jean-François Rees ◽  
André Clippe ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Sulfide ◽  
Kinetic Studies ◽  
Peroxiredoxin 6 ◽  
Arenicola Marina ◽  
Oxidation By Hydrogen Peroxide

Reaction between hydrogen sulfide and zinc oxide-titanium oxide sorbents. 1. Single-pellet kinetic studies

1990 ◽  
Vol 29 (7) ◽  
pp. 1160-1167 ◽  
Author(s):  
M. C. Woods ◽  
S. K. Gangwal ◽  
K. Jothimurugesan ◽  
Douglas P. Harrison
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Titanium Oxide ◽  
Kinetic Studies ◽  
Single Pellet

Flavin radicals, conformational sampling and robust design principles in interprotein electron transfer: the trimethylamine dehydrogenase-electron-transferring flavoprotein complex

2004 ◽  
Vol 71 ◽  
pp. 1-14
Author(s):  
David Leys ◽  
Jaswir Basran ◽  
François Talfournier ◽  
Kamaldeep K. Chohan ◽  
Andrew W. Munro ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Kinetic Studies ◽  
Molecular Assembly ◽  
Conformational Sampling ◽  
Trimethylamine Dehydrogenase ◽  
Key Residues ◽  
Electron Transferring Flavoprotein ◽  
Electron Transfer Complex

TMADH (trimethylamine dehydrogenase) is a complex iron-sulphur flavoprotein that forms a soluble electron-transfer complex with ETF (electron-transferring flavoprotein). The mechanism of electron transfer between TMADH and ETF has been studied using stopped-flow kinetic and mutagenesis methods, and more recently by X-ray crystallography. Potentiometric methods have also been used to identify key residues involved in the stabilization of the flavin radical semiquinone species in ETF. These studies have demonstrated a key role for 'conformational sampling' in the electron-transfer complex, facilitated by two-site contact of ETF with TMADH. Exploration of three-dimensional space in the complex allows the FAD of ETF to find conformations compatible with enhanced electronic coupling with the 4Fe-4S centre of TMADH. This mechanism of electron transfer provides for a more robust and accessible design principle for interprotein electron transfer compared with simpler models that invoke the collision of redox partners followed by electron transfer. The structure of the TMADH-ETF complex confirms the role of key residues in electron transfer and molecular assembly, originally suggested from detailed kinetic studies in wild-type and mutant complexes, and from molecular modelling.

Endogenous hydrogen sulfide sulfhydrates IKKβ at cysteine 179 to control pulmonary artery endothelial cell inflammation

2019 ◽  
Vol 133 (20) ◽  
pp. 2045-2059 ◽  
Author(s):  
Da Zhang ◽  
Xiuli Wang ◽  
Siyao Chen ◽  
Selena Chen ◽  
Wen Yu ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Endothelial Cell ◽  
Pulmonary Artery ◽  
Cell Model ◽  
Site Directed Mutagenesis ◽  
Critical Event ◽  
Hypertensive Rats ◽  
Pulmonary Artery Endothelial Cell

Abstract Background: Pulmonary artery endothelial cell (PAEC) inflammation is a critical event in the development of pulmonary arterial hypertension (PAH). However, the pathogenesis of PAEC inflammation remains unclear. Methods: Purified recombinant human inhibitor of κB kinase subunit β (IKKβ) protein, human PAECs and monocrotaline-induced pulmonary hypertensive rats were employed in the study. Site-directed mutagenesis, gene knockdown or overexpression were conducted to manipulate the expression or activity of a target protein. Results: We showed that hydrogen sulfide (H2S) inhibited IKKβ activation in the cell model of human PAEC inflammation induced by monocrotaline pyrrole-stimulation or knockdown of cystathionine γ-lyase (CSE), an H2S generating enzyme. Mechanistically, H2S was proved to inhibit IKKβ activity directly via sulfhydrating IKKβ at cysteinyl residue 179 (C179) in purified recombinant IKKβ protein in vitro, whereas thiol reductant dithiothreitol (DTT) reversed H2S-induced IKKβ inactivation. Furthermore, to demonstrate the significance of IKKβ sulfhydration by H2S in the development of PAEC inflammation, we mutated C179 to serine (C179S) in IKKβ. In purified IKKβ protein, C179S mutation of IKKβ abolished H2S-induced IKKβ sulfhydration and the subsequent IKKβ inactivation. In human PAECs, C179S mutation of IKKβ blocked H2S-inhibited IKKβ activation and PAEC inflammatory response. In pulmonary hypertensive rats, C179S mutation of IKKβ abolished the inhibitory effect of H2S on IKKβ activation and pulmonary vascular inflammation and remodeling. Conclusion: Collectively, our in vivo and in vitro findings demonstrated, for the first time, that endogenous H2S directly inactivated IKKβ via sulfhydrating IKKβ at Cys179 to inhibit nuclear factor-κB (NF-κB) pathway activation and thereby control PAEC inflammation in PAH.

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