Characterization of multiple metalloproteinases with fibrinogenolytic activity from the venom of Taiwan habu (Trimeresurus mucrosquamatus): protein microsequencing coupled with cDNA sequence analysis

Fractionation and proteomic analysis of the Walterinnesia aegyptia snake venom using OFFGEL and MALDI-TOF-MS techniques

Animal venoms are complex mixtures of more than 100 different compounds, including peptides, proteins, and nonprotein compounds such as lipids, carbohydrates, and metal ions. In addition, the existing compounds show a wide range of molecular weights and concentrations within these venoms, making separation and purification procedures quite tedious. Here, we analyzed for the first time by MS the advantages of using the OFFGEL technique in the separation of the venom components of the Egyptian Elapidae Walterinnesia aegyptia snake compared to two classical methods of separation, SEC and RP-HPLC. We demonstrate that OFFGEL separates venom components over a larger scale of fractions, preserve respectable resolution with regard to the presence of a given compound in adjacent fractions and allows the identification of a greater number of ions by MS (102 over 134 total ions). We also conclude that applying several separating techniques (SEC and RP-HPLC in addition to OFFGEL) provides complementary results in terms of ion detection (21 more for SEC and 22 more with RP-HPLC). As a result, we provide a complete list of 134 ions present in the venom of W. aegyptia by using all these techniques combined.

Purification and biochemical characterization of a fibrin(ogen)olytic metalloprotease from Macrovipera mauritanica snake venom which induces vascular permeability

In the present study, a novel fibrin(ogen)olytic metalloprotease from Macrovipera mauritanica snake venom was purified and characterized in terms of enzyme kinetics and substrate specificity. The purified enzyme [termed snake venom metalloprotease-Macrovipera mauritanica (SVMP‑MM)] was composed of a single polypeptide with an apparent molecular weight of 27 kDa, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminus of the enzyme was composed of NH(2)-QRFAPRYIEL-COOH, as determined by N-terminal sequencing. The Aα- and the Bβ-chains of fibrinogen were completely cleaved by SVMP-MM within 20 and 480 min, respectively. However, the γ-chain was much more resistant to digestion by the enzyme. The enzyme also exhibited proteolytic activity, cleaving the α-α polymer of cross-linked fibrin, but did not effectively digest the γ-γ polymer. To determine the kinetic parameters for SVMP-MM, a fluorescence-quenching peptide (termed o-aminobenzoic acid-HTEKLVTS-2,4-dinitrophenyl‑NH(2)) containing a K-L sequence for SVMP-MM cleavage was designed and synthesized. The optimal pH and temperature for the enzyme activity were found to be 5.5 and 37˚C, respectively, when the fluorogenic substrate was synthesized and used as a substrate. Among the various divalent cations tested, Ni(2+) and Cu(2+) showed strong inhibitory effects on enzyme activity, with an average of 69.6% inhibition. The enzyme activity was also inhibited by treatment with 1,10-phenanthroline, ethylenediaminetetraacetic acid and glycol-bis-(2‑aminoethylether)-N,N,N',N'-tetra-acetic acid, but not with aprotinin, tosyl-lysine chloromethyl ketone and tosyl-phenylalanyl chloromethyl ketone, suggesting that SVMP-MM is a metalloprotease and not a serine protease. The enzymatic parameters, including the K(M), k(cat), and k(cat)/K(M) values were estimated to be 0.015 mM, 0.031 sec(-1), and 20.67 mM(-1)sec(-1), respectively. SVMP-MM induced vascular permeability by digesting type IV collagen. The results obtained in our study demonstrate that SVMP-MM is a fibrin(ogen)olytic P-I class metalloprotease, which can induce a hemorrhagic reaction in vivo.

Crystal structure of a Trimeresurus mucrosquamatus venom metalloproteinase providing new insights into the inhibition by endogenous tripeptide inhibitors

The crystal structure of TM-1, a P-I class snake-venom metalloproteinase (SVMP) from the Trimeresurus mucrosquamatus venom, was determined at 1.8-Å resolution. The structure exhibits the typical feature of SVMPs and is stabilized by three disulfide linkages. The active site shows a deep S1' substrate-binding pocket limited by the non-conserved Pro174 at the bottom. Further comparisons with other SVMPs suggest that the deep S1' site of TM-1 correlates with its high inhibition sensitivity to the endogenous tripeptide inhibitors. Proteolytic specificity analysis revealed that TM-1 prefers substrates having a moderate-size and hydrophobic residue at the P1' position, consistent with our structural observation.

Activities against hemostatic proteins and adrenal gland ultrastructural changes caused by the brown widow spider Latrodectus geometricus (Araneae: Theridiidae) venom

Brown widow spider (BrWS) (Latrodectus geometricus) venom produces intense systemic reactions such as cramps, harsh muscle nociceptive, nauseas, vomiting and hypertension. The proposed pathogenic mechanisms resulting in these accidents have principally been damages occurring at the nervous system. However, it is suspected that there is also damage of the adrenal glands, as a result of the experimental animal's clinical manifestations, which developed symptoms compatible with acute adrenal insufficiency. We have currently found that the adrenal gland is damaged by this venom gland homogenates (VGH) producing severe alterations on cortex cells resulting in death by acute adrenal insufficiency. In general, the ultrastructural study on the glands of mice under transmission electronic microscopy observations showed alterations in the majority of the intracellular membranes within 3 to 24h. BrWSVGH also showed specific actions on extracellular matrix proteins such as fibronectin, laminin and fibrinogen. In addition, zymogram experiments using gelatin as substrates detected gelatinolytic activity. The molecular exclusion fractionation of crude BrWSVGH resulted in 15 fractions, of which F1 and F2 presented alpha/beta-fibrinogenase and fibronectinolytic activities. Fractions F6, F14 and F15 showed only alpha-fibrinogenase activity; in contrast, the gelatinolytic action was only observed in fraction F11. Only metalloproteinase inhibitors abolished all these proteolytic activities. Our results suggest that adrenal cortex lesions may be relevant in the etiopathogenesis of severe brown widow spider envenoming. To our knowledge, this is the first report on adrenal gland damages, fibrinogenolytic activity and interrelations with cell-matrix adhesion proteins caused by L.geometricus VGH. The venom of this spider could be inducing hemostatic system damages on envenomed patients.

Recombinant fibrinogenase from Agkistrodon acutus venom protects against sepsis via direct degradation of fibrin and TNF-alpha

Severe sepsis remains a leading cause of death and disability because of less effective therapy available for this disease. A complex interplay between the inflammatory factors and the coagulation pathways seems to be the fundamental mechanisms for the pathogenesis of sepsis. Here we report that recombinant fibrinogenase II (rF II) from Agkistrodon acutus plasmin-independently degraded the thrombi, and inhibited inflammatory responses by direct and specific degradation of tumor necrosis factor alpha (TNF-alpha) induced by lipopolysaccharide (LPS) without showing proteolytic activities on interleukin-1 (IL-1), cluster of differentiation 68 (CD68) and some other serum proteins. We also report that rF II effectively protected against LPS induced sepsis in a rabbit model. Administration of rF II reduced hepatic and renal damage, decreased the levels of alanine aminotransferase (ALT) and blood urea nitrogen (BUN), and increased survival rate in LPS-induced sepsis rabbits. We further confirmed the rescue effect of rF II on severe sepsis in rat caecal ligation and puncture (CLP) model. Our findings suggest that rF II could effectively protect against sepsis via direct degradation of microthrombi and inflammatory factor TNF-alpha as well as provide a novel strategy to develop a single proteinase molecule for targeting the main pathological processes of this disease.

Isolation and characterization of a novel proteinase inhibitor from the snake serum of Taiwan habu (Trimeresurus mucrosquamatus)

A proteinase inhibitor (designated as TMI) was isolated and purified from the snake serum of Taiwan habu (Trimeresurus mucrosquamatus) by using successive chromatographies which included Sephadex G-100, DEAE-Sephacel chromatographies, and C(4) reverse-phase HPLC. The purified inhibitor was shown to be a homogeneous protein with a molecular mass of about 47 or 36 kDa in the presence or absence of a reducing agent, beta-mercaptoethanol. The inhibitor decreases in molecular mass by about 23% with N-linked neuraminidase treatment, suggesting that it is a glycoprotein. Further enzymatic analyses indicated that this inhibitor possesses strong inhibitory activities toward three zinc-dependent metalloproteinases and not fibrinogenolytic serine proteases previously isolated from the venom of the same snake species with an IC(50) of about 0.2-1.1 microM. Its IC(50) value was approximately three orders of magnitude more effective than those of the tripeptide inhibitors we previously purified from the crude venom of the same snake (Biochem. Biophys. Res. Commun. 248, 562-568 (1998)). The purified inhibitor showed stronger inhibitory action against caseinolytic activities of crude venoms from closely related species of Taiwan habu than those from unrelated species. N-terminal sequence analysis showed that its sequence is distinctly different from sequences of those serum inhibitors reported for other snake species in the literature. Based on inhibition susceptibility and primary structures of various snake protease inhibitors, it is suggested that this novel inhibitor isolated from the serum of Taiwan habu may be a unique self-defense protein factor mainly for protection against envenomation from snakes of the same genus.

Characterization of three endogenous peptide inhibitors for multiple metalloproteinases with fibrinogenolytic activity from the venom of Taiwan habu (Trimeresurus mucrosquamatus)

Three small peptide components were isolated and purified from the venom of Taiwan habu (Trimeresurus mucrosquamatus), which show specific activity to inhibit the strong proteolytic activity of multiple metalloproteinases present in the crude venom. Using multiple chromatographies coupled with successive ultrafiltrations, three inhibitors, i.e. pyroglutamate-lysine-tryptophan (pyroGlu-Lys-Trp), pyroglutamate-asparagine-tryptophan (pyroGlu-Asn-Trp) and pyroglutamate-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, which corresponded to the approximate concentrations of 8.4 mM, 7.3 mM and 5.4 mM respectively in venom secretion. Detailed and unambiguous structural determination was established by amino acid analyses, mass spectrometry and microsequencing of purified peptides. Further functional characterization of these three tripeptides showed that they could weakly inhibit three metalloproteinases previously isolated from the same venom. The inhibitory activities were similar among these tripeptides 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, another venom protease inhibitor of low molecular-weight component. Since these tripeptides are the endogenous peptide inhibitors present in the lumen of venom glands, it is conceivable that they may act as a self-defensive mechanism against the auto-digestive deleterious effect of the strong metalloproteinases in vivo, particularly several zinc-dependent metalloproteinases present in crotalid and viperid venoms.

Cloning and expression of a cysteine-rich venom protein from Trimeresurus mucrosquamatus (Taiwan habu)

A full-length cDNA for cysteine-rich venom protein (CRVP) was constructed by immunoscreening and 5'-rapid amplification of cDNA ends from a cDNA library of venom gland of Trimeresurus mucrosquamatus. The predicted CRVP consisted of 183 amino acid residues including a putative signal peptide of 21 residues. Northern blot hybridization suggested the tissue-specific expression in venom gland and its corresponding length of cDNA. The predicted amino acid sequence of CRVP was homologous to a rat epididymal metalloprotein and a lizard helothermine. Amino acid sequence analysis suggested that CRVP may be a venom metalloprotein targeted against ryanodine receptors and Ca2+ release. Moreover, CRVP expressed in Escherichia coli exhibited the same antigenicity as their native venom forms of T. mucrosquamatus. This is the first report in the cloning and expression of a CRVP from the venom gland of T. mucrosquamatus.

Isolation of a venom factor devoid of proteolytic activity from Taiwan habu (Trimeresurus mucrosquamatus): N-terminal sequence homology and no functional similarity to factors IX/X-binding proteins and botrocetin

One novel venom factor was isolated and purified from the venom of Taiwan habu (Trimeresurus mucrosquamatus) using two consecutive anion-exchange and gel-filtration chromatographies followed by cation-exchange HPLC. Further characterization of the purified protein indicated that it lacks the proteolytic activity toward fibrinogen molecules, suggesting that this protein factor does not belong to the familes of metalloproteinases and thrombin-like serine proteases commonly found in the crude venoms of various crotalid snakes. The purified protein exists as a native dimeric protein of 26 kDa, consisting of two closely similar subunits of 16 and 13 kDa, held together by disulfide linkage. N-Terminal sequence analysis revealed that both chains are homologous to each other at the N-terminal fragment and also similar to the factors IX/X-binding protein isolated from Trimeresurus flavoviridis and botrocetin from Bothrops jararaca. This study points to the existence of one new two-chain venom factor without fibrinogenase activity from Taiwan habu, which, in contrast to botrocetin, promotes platelet agglutination even in the absence of von Willebrand factor. Unlike factors IX/X-binding proteins, it did not show affinity to coagulation factors IX and X in the presence of Ca2+ ion. It also shows no inhibition on thrombin, in contrast with bothrojaracin, a thrombin inhibitor isolated from Bothrops jararaca venom. We have therefore named this novel venom factor trimecetin to distinguish it from some structurally related venom factors present in various crotalid and viperid snakes.