Inhibition of starfish oocyte maturation by leupeptin analogs, potent trypsin inhibitors.

Inhibition of subsite-substituted leupeptin analogs, potent trypsin inhibitors, on 1-methyladenine-induced germinal vesicle breakdown was investigated in a starfish, Asterina pectinifera. Of benzyloxycarbonyl(Z)-Leu-P2-argininals, the analog with Ser at P2 residue was the strongest inhibitor, and those with Pro, Leu greater than Thr greater than Gly were followed in this order. In Z-P3-Ser-argininals, ranking of the inhibitory ability was as follows: Phe greater than Leu much greater than Pro greater than Ala at P3 residue. Among 11 analogs synthesized, Z-Phe-Ser-argininal showed the strongest inhibition. The inhibitory potency of the analog was 100-fold stronger than that of leupeptin (acetyl-Leu-Leu-argininal). Thus, trypsin-like enzyme possessing a narrow subsite specificity participates in oocyte maturation in the starfish.