Abstract
A sweet tasting peptide containing the L-lysine residue, N-acetyl-L-phenylalanyl-L-lysine, was synthesized from N-acetyl-L-phenylalanine ethyl ester (Ac-Phe-OEt) as donor and L-lysine esters as acceptor nucleophiles by an α-chymotrypsin catalyzed reaction. It was revealed by HPLC analysis that the reaction proceeded most satisfactorily at pH 9 within 3 min in a reaction system containing 100 mM Ac-Phe-OEt, equimolar esters of lysine and 10 JIM of the enzyme, where the product yield based on the donor concentration was 53 % for ethyl, 67 % for n-butyl and 31 % for benzyl esters. The highest reaction yield (75 %) was attained by using a double molar excess of lysine n-butyl ester. The present results suggest that α-chymotrypsin may become a useful tool for the synthesis of peptides containing basic amino acids.
