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Please use this identifier to cite or link to this item: https://hdl.handle.net/20.500.12008/47182 How to cite
Title: Acidity of persulfides and its modulation by the protein environments in sulfide quinone oxidoreductase and thiosulfate sulfurtransferase.
Authors: Benchoam, Dayana
Cuevasanta, Ernesto
Roman, Joseph V.
Banerjee, Ruma
Alvarez, Beatriz
Type: Artículo
Descriptors: PERSULFUROS, SULFURO DE HIDROGENO, EFECTO ALFA, TIOL, SULFURO, QUINONA OXIDORREDUCTASA, TIOSULFATO, AZUFRETRANSFERASA, RODANASA
Issue Date: 2024
Abstract: Persulfides (RSSH/RSS−) participate in sulfur metabolism and are proposed to transduce hydrogen sulfide (H2S) signaling. Their biochemical properties are poorly understood. Herein, we studied the acidity and nucleophilicity of several low molecular weight persulfides using the alkylating agent, monobromobimane. The different persulfides presented similar pKa values (4.6–6.3) and pH-independent rate constants (3.2–9.0 × 103 M−1 s−1), indicating that the substituents in persulfides affect properties to a lesser extent than in thiols because of the larger distance to the outer sulfur. The persulfides had higher reactivity with monobromobimane than analogous thiols and putative thiols with the same pKa, providing evidence for the alpha effect (enhanced nucleophilicity by the presence of a contiguous atom with high electron density). Additionally, we investigated two enzymes from the human mitochondrial H2S oxidation pathway that form catalytic persulfide intermediates, sulfide quinone oxidoreductase and thiosulfate sulfurtransferase (TST, rhodanese). The pH dependence of the activities of both enzymes was measured using sulfite and/or cyanide as sulfur acceptors. The TST halfreactions were also studied by stopped-flow fluorescence spectroscopy. Both persulfidated enzymes relied on protonated groups for reaction with the acceptors. Persulfidated sulfide quinone oxidoreductase appeared to have a pKa of 7.8 ± 0.2. Persulfidated TST presented a pKa of 9.38 ± 0.04, probably due to a critical active site residue rather than the persulfide itself. The TST thiol reacted in the anionic state with thiosulfate, with an apparent pKa of 6.5 ± 0.1. Overall, our study contributes to a fundamental understanding of persulfide properties and their modulation by protein environments.
Publisher: American Society for Biochemistry and Molecular Biology
IN: Journal of Biological Chemistry, v. 300, nº 5, 2024 -- e107149
Citation: Benchoam, D, Cuevasanta, E y otros. Acidity of persulfides and its modulation by the protein environments in sulfide quinone oxidoreductase and thiosulfate sulfurtransferase. Journal of Biological Chemistry [en línea], v. 300, nº 5, 2024. -- e107149. 14 p.
Appears in Collections:Publicaciones académicas y científicas - Facultad de Química

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