SYNTHESIS AND PROTEASE-CATALYZED HYDROLYSIS OF A NOVEL HYDRAZINOPEPTIDE

In order to explore the potentiality of hydrazinopeptides as protease inhibitors, the resistance of the hydrazinopeptidic bond toward proteo lysis was investigated. To this end, the novel hydrazinohexapeptide Z- Ala(2)-Pro-Val-hlle-Leu-OMe (1), where hIle represents hydrazinoisoleu cine, was designed and synthesized together with the p arent peptide Z -Ala(2)-Pro-Val-Ile-Leu-OMe (2). The interactions of 1 and 2 with hum an leukocyte elastase (HLE) and porcine pancreatic elastase (PPE) were analyzed comparatively. We observed that 1 behaved as a substrate for both elastases, without the formation of a stable acyl-enzyme as in t he case of azapeytides. Compounds 1 and 2 were cleaved at the same sit e (-Val-//-NH-) with a slight delay of hydrolysis for 1 compared to 2 (k(cat)/K-M for 1 vs. 2 decreased by a factor of 2.7 for the HLE-catal yzed hydrolysis at pH 8.0 and 25 degrees C). The presence of the hydra zinopeptidic bond (-CONHNH-) in 1 reduced by a factor of 4.7 the appar ent enzyme affinity without abolishing it. These results indicate that suitably designed hydrazinopeptides may represent interesting targets in the search for protease resisting pseudopeptides. (C) Munksgaard 1 993.