Synthesis and Antipepsin Activities of Peptides having a Valine or Valylvaline Moiety at the N-Terminus

Abstract

A series of peptides having a valine or valyvaline moiety at the N-terminus, 1-13, was prepared and their antipepsin activities were tested. All of the peptides possessing an N-acyl-Val-Val moiety, except one, showed some inhibitory activity against pepsin, while compounds lacking N-acyl-Val-Val showed no inhibition even at a concentration of 50 μg/ml. Compound 12, a pepstatin analog, in which a tyrosine residue is present instead of AHMHA of pepstatins, was the most potent inhibitor among the synthetic peptides, but its activity was markedly lower than that of pepstatin A. Compounds 10, 12, and 13 showed neither agonistic nor antagonistic effects on pepstatin A, suggesting major differences in binding abilities of the synthetic peptides and of pepstatin A to the enzyme. The importance of the AHMHA residue of pepstatins in relation to the inhibitory activity is discussed.