Inhibition of Mouse Blastocyst Hatching by Subsite-Specific Trypsin Inhibitors, Peptidyl Argininals.

To explore the substrate or subsite specificity of a mouse hatching enzyme, effects of leupeptin [acetyl(P )-Leu(P )-Leu(P )-argininal(P )] and its analogs (peptidyl argininals) on mouse blastocyst hatching were investigated. The compounds containing benzyloxycarbonyl group (Z) in the P position inhibited the hatching more strongly than those containing acetyl group or unprotected N-terminal amino acid. Among five Z-Leu-P -argininals, a derivative containing a P Ser residue was the most potent inhibitor, and the derivatives containing Leu, Thr, Pro, and Gly in the P position followed in this order. Then, we synthesized four Z-P -Ser-argininals and tested their effects on hatching. The result indicated that the compound with Phe residue in the P position was the strongest inhibitor, and the Leu-, Pro-, and Ala-containing derivatives were ranked in this order. Thus, among Z-dipeptidyl-argininals tested, Z-Phe-Ser-argininal most potently inhibited the mouse embryonic hatching, suggesting the preference of the mouse hatching enzyme for Phe(P )-Ser(P )-Arg(P ) sequence as a substrate.