Hydrolysis and transpeptidation of lysine peptides by trypsin.

The study of the tryptic digestion of poly-L-lysine (Katchalski, 1951; Waley & Watson, 1953) has shown that lysine oligopeptides appear duringthe reaction. A better understanding of the mode of action of trypsin on the high-molecular-weight peptide might be gained by a study of the action of the enzyme on a homologous series of lysine peptides (for a preliminary note see Katchalski, Berger & Levin, 1954). In the present article the behaviour of the following substrates towards trypsin is reported: L-lysine amide, di-L-lysine, tri-L-lysine, di-L-lysine amide, glycyl-L-lysine amide, L-lysylglycine amide, benzoyl-L-lysine, benzoyldi-L-lysine and benzoyltri-L-lysine. In agreement with the results of Waley & Watson (1954), it will be shown that trypsin mediates transpeptidation as well as hydrolysis of many of the substrates investigated. The effect of free c-amino and x-carboxyl groups on hydrolysis and transpeptidation will also be shown. In the synthesis of the lysine peptides and their derivatives the mixed anhydride method of Wieland & Sehring (1950) as well as the azide method was used. As it has been shown (Vaughan, 1952; Vaughan & Eichler, 1953), that racemization may accompany peptide synthesis when mixed anhydrides of acylated amino acids are used, the azide method was employed in the synthesis of benzoyldi-L-lysine and benzoyltri-L-lysine.