Glutathione in Relation to Transpeptidation Reactions

Abstract

This chapter discusses glutathione in relation to transpeptidation reactions. The majority of transpeptidation reactions consist of the transfer of α-amino-acyl groups from peptide or amide linkage in the donor molecule to new linkage with the amino group of the acceptor molecule; however, in addition, enzymes catalyzing transfer of γ -glutamyl and β-aspartyl groups have been discovered. All the known transpeptidation and transamidation reactions are of the carboxyl-transfer type. The capacity to donate γ -glutamyl groups is not an exclusive property of glutathione and, indeed, γ -glutamylcysteine, an intermediate in the synthesis of glutathione (GSH), is equally effective. The chapter presents the role of GSH as a coenzyme in the glyoxalase and triosephosphate dehydrogenase systems in which the sulphydryl group of GSH participates in the formation and the transfer of acyl groups.