Action of Trypsin on α-Carbethoxy-L-lysyl-L-serylglycine and its O-Phosphorylated Analogue

Abstract

THE occurrence and isolation of phosphorylated peptides from enzymic hydrolysates of casein have already been reported^1,2. These peptides exhibit unusual resistance to further proteolytic action, a fact which has been correlated with the existence of O-phosphorylated serine residues in their molecules. In order to investigate further the resistance of such peptides to the action of trypsin, certain synthetic peptide-substrates suitable for this enzyme have been tested. Thus α-carbethoxy-L-lysyl-L-serylglycine and α - carbethoxy - L - lysyl - (O - phosphoryl) - L - serylglycine were synthesized as follows.