CHARACTERIZATION OF 3 ENDOGENOUS PEPTIDE INHIBITORS FOR MULTIPLE METALLOPROTEINASES WITH FIBRINOGENOLYTIC ACTIVITY FROM THE VENOM OF TAIWANHABU (TRIMERESURUS-MUCROSQUAMATUS)

Three small peptide components were isolated and purified from the ven om of Taiwan habu (Trimeresurus mucrosquamatus), which show specific a ctivity to inhibit the strong proteolytic activity of multiple metallo proteinases present in the crude venom. Using multiple chromatographie s coupled with successive ultrafiltrations, three inhibitors, i.e. pyr oglutamate-lysine-tryptophan (pyroGlu-Lys-Trp), pyroglutamate-asparasn e-tryptophan (pyroGlu-Asn-Trp) and pyroglutarnate-glutamine-tryptophan (pyroGlu-Gln-Trp) were obtained in good yields and high homogeneity. The yields of these peptide fractions were estimated to be about 0.65 mg, 0.55 mg and 0.42 mg from 250 mg total lyophilized crude venom, whi ch corresponded to the approximate concentrations of 8.4 mM, 7.3 mM an d 5.4 mM respectively in venom secretion. Detailed and unambiguous str uctural determination was established by amino acid analyses, mass spe ctrometry and microsequencing of purified peptides. Further functional characterization of these three tripeptides showed that they could we akly inhibit three metalloproteinases previously isolated from the sam e venom. The inhibitory activities were similar among these tripeptide s and their IC50 (concentration for 50% inhibition) were estimated in a range of 0.20-0.95 mM, which is much more effective than citrate, an other venom protease inhibitor of low molecular-weight component. Sinc e these tripeptides are the endogenous peptide inhibitors present in t he lumen of venom glands, it is conceivable that they may act as a sel f-defensive mechanism against the auto-digestive deleterious effect of the strong metalloproteinases in vivo, particularly several zinc-depe ndent metalloproteinases present in crotalid and viperid venoms. (C) 1 998 Academic Press.