The protease-catalyzed syntheses of 3 peptides derivatives, Boc-Leu-Ile-Cys(Bzl)-N2H2Ph (I), Boc-Gly-Cys(Bzl)-Ser(Bzl)-Gly-Lys(Z)-N2H2Ph (II), and Z-Leu-Gly-Leu-Trp-N2H2Ph, from amino acid sequence 598~609 of gp 41 of Human Immunodeficiency Virus-I (HIV-I), are reported. The C-terminal phenylhydrazide, as well as all the peptide bonds were constructed by papain-mediated synthesis via stepwise elongation. To suppress the side reaction of the secondary hydrolysis, the Na-protected amino acid esters were used as carboxyl components to react with the nucleophiles, amino acid or peptide phenylhydrazides, in an alkaline media. MeCN was more suitable than MeOH for the enzymic peptide synthesis. For comparison, I and II were also synthesized by the conventional DCCI method. The products obtained from both methods were shown to be identical by several criteria.

Key words: PAPAIN, PEPTIDE BOND