Amino Acids and Peptides. XLIV. Synthesis of Stereoisomeric Pentapeptides of Thiol Proteinase Inhibitor

Abstract

Stereoisomers of thiol proteinase inhibitor (TPI) were synthesized by a conventional solution method. Among them, iNoc-D-Gln-Val-Ala-Ala-pNA weakly inhibited the aminolytic activity of papain, although iNoc-Gln-Val-Val-Ala-Ala-pNA inhibited papain activity fairly potently. However, the other five D-amino acid-containing peptides did not show any inhibitor effects on papain. The circular dichroism (CD) spectra of the enzyme-peptides mixtures were measured in order to study the relationship between the peptide anilides-papain interaction and the inhibitory activity.