Enzymatic Peptide Synthesis with p-Guanidinophenyl and p-(Guanidinomethyl)phenyl Esters as Acyl Donors

Abstract

Two series of "inverse substrates", N-Boc-amino acid p-guanidinophenyl and p-(guanidinomethyl)phenyl esters, were prepared as acyl donor components for enzymatic peptide synthesis. The kinetic behavior of these esters toward bovine and Streptomyces griseus (SG) trypsin was analyzed. 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 most efficient catalyst among the enzymes tested (bovine, porcine, and SG trypsin).