Interaction kinetics of selenium-containing compounds with oxidants.

Interaction kinetics of selenium-containing compounds with oxidants.
Free Radic Biol Med. 2020 May 18;:
Authors: Carroll L, Gardiner K, Ignasiak M, Holmehave J, Shimodaira S, Breitenbach T, Iwaoka M, Ogilby PR, Pattison DI, Davies MJ
Abstract
Selenium compounds have been identified as potential oxidant scavengers for biological applications due to the nucleophilicity of Se, and the ease of oxidation of the selenium centre. Previous studies have reported apparent second order rate constants for a limited number of oxidants (e.g. HOCl, ONOOH) with some selenium species, but these data are limited. Here we provide apparent second order rate constants for reaction of selenols (RSeH), selenides (RSeR') and diselenides (RSeSeR') with biologically-relevant oxidants (HOCl, H2O2, other peroxides) as well as overall consumption data for the excited state species singlet oxygen (1O2). Selenols show very high reactivity with HOCl and 1O2, with rate constants > 108 M-1 s-1, whilst selenides and diselenides typically react with rate constants one- (selenides) or two- (diselenides) orders of magnitude slower. Rate constants for reaction of diselenides with H2O2 and other hydroperoxides are much slower, with k for H2O2 being <1 M-1 s-1, and for amino acid and peptide hydroperoxides ∼102 M-1 s-1. The rate constants determined for HOCl and 1O2 with these selenium species are greater than, or similar to, rate constants for amino aci...

Source: Free Radical Biology and Medicine - May 17, 2020 Category: Biology Authors: Carroll L, Gardiner K, Ignasiak M, Holmehave J, Shimodaira S, Breitenbach T, Iwaoka M, Ogilby PR, Pattison DI, Davies MJ Tags: Free Radic Biol Med Source Type: research