Disulfides form persulfides at alkaline pH leading to potential overestimations in the cold cyanolysis method

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Título

Disulfides form persulfides at alkaline pH leading to potential overestimations in the cold cyanolysis method

Tema

DISULFURO 
PERSULFURO
GLUTATION
AZUFRE
BIBLIOGRAFIA NACIONAL QUIMICA
2023

Abstract

It is well established that proteins and peptides can release sulfur under alkaline treatment, mainly through the β-elimination of disulfides with the concomitant formation of persulfides and dehydroalanine derivatives. In this study, we evaluated the formation of glutathione persulfide (GSSH/GSS- ) by exposure of glutathione disulfide (GSSG) to alkaline conditions. The kinetics of the reaction between GSSG and HO- was investigated by UV–Vis absorbance, reaction with 5,5′-dithio-bis-(2-nitrobenzoic acid) (DTNB), and cold cyanolysis, obtaining an apparent second-order rate constant of ~10-3 M-1 s -1 at 25 ◦C. The formation of GSSH and the dehydroalanine derivative was confirmed by HPLC and/or mass spectrometry. However, the mixtures did not equilibrate in a timescale of hours, and additional species, including thiol and diverse sulfane sulfur compounds were also formed, probably through further reactions of the persulfide. Cold cyanolysis is frequently used to quantify persulfides, since it measures sulfane sulfur. This method involves a step in which the sample to be analyzed is incubated with cyanide at alkaline pH. When cold cyanolysis was applied to samples containing GSSG, sulfane sulfur products that were not present in the original sample were measured. Thus, our results reveal the risk of overestimating the amount of sulfane sulfur compounds in samples that contain disulfides due to their decay to persulfides and other sulfane sulfur compounds at alkaline pH. Overall, our study highlights that the β-elimi nation of disulfides is a potential source of persulfides, although we do not recommend the preparation of GSSH from incubation of GSSG in alkali. Our study also highlights the importance of being cautious when doing and interpreting cold cyanolysis experiments.

Autor

Cuevasanta, Ernesto
Semelak, Jonathan A.
Mastrogiovanni, Mauricio
Estrin, Darío A.
Möller Rodríguez, Matías Nicolás
Alvarez, Beatriz

Fuente

Free Radical Biology and Medicine v.207, 2023. -- pp. 63-71

Editor

Elsevier

Fecha

2023

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Formato

PDF

Extent

9 p.

Idioma

Inglés

Tipo

Artículo

Identificador

10.1016/j.freeradbiomed.2023.07.006

Document Item Type Metadata

Original Format

PDF
Fecha de agregación
August 28, 2023
Colección
Bibliografía Nacional Química
Tipo de Elemento
Document
Etiquetas
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Citación
Benchoam, Dayana, “Disulfides form persulfides at alkaline pH leading to potential overestimations in the cold cyanolysis method,” RIQUIM - Repositorio Institucional de la Facultad de Química - UdelaR, accessed May 25, 2024, https://riquim.fq.edu.uy/items/show/6683.
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