ENZYMATIC PEPTIDE-SYNTHESIS WITH P-GUANIDINOPHENYL AND P-(GUANIDINOMETHYL)PHENYL ESTERS AS ACYL DONORS

Two series of ''inverse substrates'', N-Boc-amino acid p-guanidinophen yl and p-(guanidinomethyl)phenyl esters, were prepared as acyl donor c omponents for enzymatic peptide synthesis. The kinetic behavior of the se esters toward bovine and Streptomyces griseus (SG) trypsin was anal yzed. The spatial requirement of the active site of these enzymes for catalytic efficiency is discussed based on the steric characteristics of the substrates, These substrates were found to couple readily with amino acid p-nitroanilides to produce peptides. SG trypsin was the mos t efficient catalyst among the enzymes tested (bovine, porcine, and SG trypsin).