Evaluation of Hydroxyl Radical Reactivity by Thioether Group Proximity in Model Peptide Backbone: Methionine versus S-Methyl-Cysteine.
Int J Mol Sci
; 23(12)2022 Jun 11.
Article
em En
| MEDLINE
| ID: mdl-35742994
ABSTRACT
Hydroxyl radicals (HOâ¢) have long been regarded as a major source of cellular damage. The reaction of HO⢠with methionine residues (Met) in peptides and proteins is a complex multistep process. Although the reaction mechanism has been intensively studied, some essential parts remain unsolved. In the present study we examined the reaction of HO⢠generated by ionizing radiation in aqueous solutions under anoxic conditions with two compounds representing the simplest model peptide backbone CH3C(O)NHCHXC(O)NHCH3, where X = CH2CH2SCH3 or CH2SCH3, i.e., the Met derivative in comparison with the cysteine-methylated derivative. We performed the identification and quantification of transient species by pulse radiolysis and final products by LC-MS and high-resolution MS/MS after γ-radiolysis. The results allowed us to draw for each compound a mechanistic scheme. The fate of the initial one-electron oxidation at the sulfur atom depends on its distance from the peptide backbone and involves transient species of five-membered and/or six-membered ring formations with different heteroatoms present in the backbone as well as quite different rates of deprotonation in forming α-(alkylthio)alkyl radicals.
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Base de dados:
MEDLINE
Assunto principal:
Radical Hidroxila
/
Metionina
Idioma:
En
Revista:
Int J Mol Sci
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Polônia