Reaction rates of glutathione and ascorbate with alkyl radicals are too slow for protection against protein peroxidation in vivo

Thomas Nauser*, Janusz M. Gebicki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Reaction kinetics of amino acid and peptide alkyl radicals with GSH and ascorbate, the two most abundant endogenous antioxidants, were investigated by pulse radiolysis. Rate constants in the order of 106 M−1s−1 were found. Alkyl radicals react at almost diffusion controlled rates and irreversibly with oxygen to form peroxyl radicals, and competition with this reaction is the benchmark for efficient repair in vivo. We consider repair of protein radicals and assume comparable rate constants for the reactions of GSH/ascorbate with peptide alkyl radicals and with alkyl radicals on a protein surface. Given physiological concentrations of oxygen, GSH and ascorbate, protein peroxyl radicals will always be a major product of protein alkyl radicals in vivo. Therefore, if they are formed by oxidative stress, protein alkyl radicals are a probable cause for biological damage.

Original languageEnglish
Pages (from-to)118-123
Number of pages6
JournalArchives of Biochemistry and Biophysics
Volume633
DOIs
Publication statusPublished - 1 Nov 2017

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