Photosensitized deamination of sulfur-amino acids by flavin mononucleotide.

Abstract

Abstract— S‐Methylcysteine, methionine and cystine were found to be photochemically deaminated at a much higher rate than methionine sulfoxide, homomethionine and other non‐sulfur amino acids in the presence of flavin mononucleotide. These data strongly support the view that the initial oxidation of those sulfur‐amino acids by the photoactivated flavin is a one‐electron abstraction from the sulfur atom followed by an intramolecular electron transfer from the carboxyl anion of the amino acid to the sulfinium radical, resulting in the decarboxylation‐deamination.