The reaction of cystine and Alanine-3-sulphinic acid with halogens

Abstract

Aqueous chlorine and bromine react with cystine, cysteine, alanine-3- sulphinic acid, and cystine S,S-dioxide to give cysteic acid (3) and cysteicylcysteic acid (2).' When the reaction is performed in the presence of other amino acids it is possible to obtain mixed peptides. The mechanism of formation of the peptide bond is discussed and a sulphonic-carboxylic acid mixed anhydride is proposed as an intermediate.