OH Radical-induced Crosslinks of Methionine Peptides

Abstract
Reactions of radiation-generated OH radicals with methionine (Met) and its homopeptides, l-Met-l-Met and tri-l-Met, were investigated through reaction products. Samples of irradiated Met and HCl-hydrolysates of its irradiated homopeptides were trimethylsilylated and analysed by capillary gas chromatography-mass spectrometry. Mass spectra taken revealed the formation of three products, 2-amino-4-(methyldithio)butanoic acid, 4,4′-thiobis(2-aminobutanoic acid) and homocystine. G values of these products were determined to be 0·10, 0·16 and 0·30, respectively.