Structures and Functions of Snake Venom Metalloproteinases (SVMP) from Protobothrops venom Collected in Japan.

Snake venom metalloproteinases (SVMP) are widely distributed among the venoms of Crotalinae and Viperidae, and are organized into three classes (P-I, P-II and P-III) according to their size and domain structure. P-I SVMP are the smallest SVMP, as they only have a metalloproteinase (M) domain. P-II SVMP contain a disintegrin-like (D) domain, which is connected by a short spacer region to the carboxyl terminus of the M domain. P-III SVMP contain a cysteine-rich (C) domain, which is attached to the carboxyl terminus of the D domain. Some SVMP exhibit hemorrhagic activity, whereas others do not. In addition, SVMP display fibrinolytic/fibrinogenolytic (FL) activity, and the physiological functions of SVMP are controlled by their structures. Furthermore, these proteinases also demonstrate fibrinogenolytic and proteolytic activity against synthetic substrates for matrix metalloproteinases and ADAM (a disintegrin and metalloproteinase). This article describes the structures and FL, hemorrhagic, and platelet aggregation-inhibiting activity of SVMP derived from Protobothrops snake venom that was collected in Japan.

Design and Synthesis of Non-peptide RGD Mimics for Evaluation of Their Utility as Anti-platelet Agents.

Arg-Gly-Asp (RGD) mimics were synthesized and their anti-platelet activity was evaluated. A concise method was developed for the synthesis of the target compounds from dehydroepiandrosterone and Wieland-Miescher and Hajos-Parrish ketones, which are suitable for readily available platform. Among the synthesized compounds, the perhydronaphthalene framework with a 3-(4-piperidinyl)propoxyl structure 3e possessed the highest anti-aggregative activity. The IC50 values of 3e were 0.91 mM (ADP initiation) and 0.54 mM (collagen initiation).

Amino acid sequence of a kinin-releasing enzyme, KR-E-1, from the venom of Agkistrodon caliginosus (Kankoku-mamushi).

The amino acid sequence of a bradykinin-releasing enzyme, named KR-E-1, isolated from the venom of Agkistrodon caliginosus (Kankoku-mamushi) was determined by Edman sequencing of the peptides which was derived from digests with cyanogen bromide, hydroxylamine, achromobacter protease I, trypsin, V8 protease, arginine endopeptidase, and endoproteinase Asp-N. KR-E-1 consisted of 235 amino acids and showed conservation of the catalytic amino acid residues (His(57), Asp(102), and Ser(195)) of the chymotrypsin family of serine protease in its amino acid sequence. The carboxy-terminal amino acid, Phe, was determined using carboxypeptidase Y. This enzyme contains glucosamine and an N-linked glycosylation site. KR-E-1 showed 32, 31, 65, 65, and 67% sequence homology to human kallikrein, bovine thrombin, KN-BJ 2, elegaxobin, and elegaxobin II, respectively. The characteristic of structure of KR-E-1 was found to involve hydrophobic amino acid residues abundantly localizing in positions 1-50, with lysine residues abundantly localizing in positions 73-101.

Distribution of low molecular weight platelet aggregation inhibitors from snake venoms.

An assay of platelet aggregation inhibitors measured by the turbidimeter using Aggregometer PAM 8C (Mebanix) was performed after each crude snake venom (57 species) was subjected to ultrafiltration using MILLIPORE UFP 1 LGC. The snake venoms of Viperidae (three species), Elapidae (11 species), and Hydrophiidae (two species) inhibited ADP-induced rabbit platelet aggregation. In particular, six venoms of Bitis gabonica, Pseudocerastes persicus, Dendroaspis angusticeps, D. polylepis, Ophiophagus hannah, and N. nigricollis crawshawii strongly inhibited platelet aggregation. Furthermore, adenosine was identified from Bitis gabonica venom using HPLC and FAB/MS analysis.

Effect of amino acids near the RGD sequence on binding activities between αIIbß3 integrin and fibrinogen in the presence of RGD-containing synthetic peptides from elegantin and angustatin.

Elegantin and angustatin, which were isolated from the snake venoms of Protobothrops elegans and Dendroaspis angusticeps, markedly inhibit binding between platelet integrins and fibrinogen via the Arg-Gly-Asp (RGD) sequence. Angustatin, which is a three-finger toxin containing the RGD sequence, inhibits platelet aggregation almost ten times more strongly than disintegrin isolated from the venoms of Viperidae and Crotalidae. The RGD sequences of both polypeptides are located at the top of hairpin loops, and the composition of the RGD loop is very important for binding to integrin. We investigated the effects of synthetic RGD loop peptides from angustatin and elegantin on ADP- or collagen-induced platelet aggregation and αIIbß3-fibrinogen binding. Synthetic angustatin (PRGDMP)-type peptides inhibited platelet aggregation more strongly than elegantin (ARGDDX)-type peptides. In particular, the cyclic angustatin peptide (CPRGDMPC) inhibited ADP- and collagen-induced platelet aggregation at least 10-50 times more strongly than the other peptides. The cyclic angustatin peptide (CPRGDMPC) was also the strongest inhibitor of binding between αIIbß3 and fibrinogen, the IC50 of this peptide was approximately 2.58µM. Regarding the inhibition of binding between αIIbß3 and fibrinogen, CPRGDMPC demonstrated a stronger inhibitory and more stable effect in the presence of Mg2+ than in the presence of Ca2+.

Substrate specificity of two thrombin like enzymes (elegaxobin, elegaxobin II) from the venom of Trimeresurus elegans (Sakishima-habu), using neutralizing antibody.

We reported previously that elegaxobin and elegaxobin II cause the release of fibrinopeptide A alone from rabbit fibrinogen. Elegaxobin II is a thrombin-like enzyme that possesses kinin-releasing activity, and shows a characterization obviously different from elegaxobin. To study the substrate specificities of elegaxobin and elegaxobin II against fibrinogen, we investigated whether anti-elegaxobin or anti-elegaxobin II antibody counteracts those enzymatic activities. Anti-elegaxobin II antibody effectively counteracted the thrombin-like activity of elegaxobin and elegaxobin II in comparison to the anti-elegaxobin antibody. The anti-elegaxobin II antibody only counteracted the thrombin-like activity, whereas did not counteract TAME hydrolytic activity and weakly counteract the kinin-releasing activity. Furthermore, we investigated which part of elegaxobin II as an antigen this antibody connects with specifically, using M-peptides derived from digests with CNBr. As a result, anti-elegaxobin II antibody bound specifically to the M-peptide including C-terminal portion. In particular, the anti-elegaxobin II antibody connected to position 220-239 (AQPHEPGSYTNVFDHLDWIK), containing His(223).

Purification and characterization of two platelet-aggregation inhibitors, named angustatin and H-toxin TA(2), from the venom of Dendroaspis angusticeps.

Angustatin and H-toxin TA2 were purified from unfractionated Dendroaspis angusticeps venom (0.3 g) using S-Sepharose fast flow column chromatography, gelfiltration on a Sephadex G-50 column, and reverse-phase HPLC. The purified materials strongly inhibited ADP-induced platelet aggregation. The primary structure of angustatin was determined by the Edman degradation of peptides derived from digestions with endopeptidese Arg-C and α-chymotrypsin. Angustatin, which was composed of 59 amino acid residues and an RGD sequence, was identified as a short-length inhibitor similar to mambin, dendroaspin, echistatin, and eristicophin. Angustatin shared 83%, 17%, and 15% homologies with mambin, eristicophin, and echistatin, respectively. On the other hand, H-toxin TA2 did not conserve the RGD sequence in its structure; it was replaced for the Glu-Met-Leu sequence. Furthermore, the amino acid sequence of H-toxin TA2 corresponded to toxin TA2, excluding the amino acid residue of His28Arg.

Purification and characterization of two high molecular mass snake venom metalloproteinases (P-III SVMPs), named SV-PAD-2 and HR-Ele-1, from the venom of Protobothrops elegans (Sakishima-habu).

We herein identified two high molecular mass metalloproteinases, named SV-PAD-2 and HR-Ele-1, in the venom of Protobothrops elegans. HR-Ele-1 appeared as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) regard under reducing and non-reducing conditions, and the molecular mass of this protease was approximately 60 kDa under reducing conditions. On the other hand, the molecular masses of SV-PAD-2 on SDS-PAGE were 110 kDa under the non-reducing condition and 52 kDa under the reducing condition. These SVMPs exhibited fibrinogenolytic and enzymatic activities against synthetic substrates for matrix metalloproteinases (MMPs) and the insulin B-chain, and were both inhibited by EDTA. SV-PAD-2 inhibited ADP- and collagen-induced platelet aggregation, with IC50 values of 240 nM and 185 nM, respectively. HR-Ele-1 exhibited hemorrhagic activity, and its minimum hemorrhagic dose (MHD) was 0.05 µg in the guinea pig.

Purification and characterization of a thrombin like enzyme, elegaxobin II, with lys-bradykinin releasing activity from the venom of Trimeresurus elegans (Sakishima-Habu).

A thrombin like enzyme, named elegaxobin II, with Lys-bradykinin releasing activity was purified from the venom of Trimeresurus elegans (Sakishima-habu) by gel-filtration on Sephadex G-100, and ion-exchange chromatography on the Q-Sepharose Fast Flow. By this procedure, about 9mg of purified enzyme was obtained from 1.1g of the venom. The purified enzyme showed a single protein band, the molecular weight of which was estimated to be about 35,000Da by sodium dodecyl sulfate-PAGE) under reducing condition, and this enzyme was found to contain a carbohydrate moiety. The specific activity of this enzyme toward tosyl-L-arginine methyl ester (TAME) was 250 TAME units/mg of protein. This enzyme clotted only rabbit fibrinogen, whereas human and bovine fibrinogens were unaffected. In the fibrinogen-fibrin conversion, this enzyme released only fibrinopeptide A from rabbit fibrinogen, whereas it did not release fibrinopeptide B. Furthermore, elegaxobin II released Lys-bradykinin when the enzyme was incubated with bovine plasma. The esterase activity was inhibited by p-amidinophenylmethanesulfonyl fluoride hydrochloride (p-APMSF), suggesting that this enzyme is a serine protease. The N-terminal sequence (Val-Ile-Gly-Gly) of this enzyme was identical to the typical sequence of serine proteinases.

Amino acid sequence of a thrombin like enzyme, elegaxobin II, from the venom of Trimeresurus elegans (Sakishima-Habu).

The amino acid sequence of a thrombin like enzyme , named elegaxobin II, isolated from the venom of Trimeresurus elegans (Sakishima-habu) was determined by Edman sequencing of the peptides which was derived from digests with cyanogen bromide, achromobacter protease I, trypsin, endoproteinase Asp-N, and chymotrypsin. Elegaxobin II consisted of 233 amino acids and showed conservation of the catalytic amino acid residues (His(57), Asp(102), and Ser(195)) of chymotrypsin family serine protease in its amino acid sequence. The carboxyterminal amino acid, Leu, was determined using carboxypeptidase Y. This enzyme contains glucosamine and an N-linked glycosylation site. Elegaxobin II was 91% homologous in sequence to elegaxobin and protease I from the same snake venom, and it was 67, 75, 31 and 26% homologous in sequences to flavoxobin, KN-BJ 2, human kallikrein and bovine thrombin, respectively. Elegaxobin II lacked thrombin's ETW (146-148) loop, as well as its functionally important YPPW (60-insertion loop).

Amino acid sequence of a thrombin like enzyme, elegaxobin, from the venom of Trimeresurus elegans (Sakishima-habu).

The amino acid sequence of a thrombin like enzyme, named elegaxobin, isolated from the venom of Trimeresurus elegans (Sakishima-habu) was determined by Edman sequencing of the peptides, derived from digests with cyanogen bromide, hydroxylamine, achromobacter protease I, trypsin, V8 protease, and chymotrypsin. Elegaxobin showed conservation of the catalytic amino acid residues (His, Asp, and Ser) of trypsin like serine protease in the amino acid sequence. The carboxy-terminal amino acid, Leu, was determined using carboxypeptidase Y. Elegaxobin consisted of 233 amino acids and had a calculated molecular weight of 25,439. Elegaxobin was 53, 59, 26 and 40% homologous in sequence to ancrod, flavoxobin, bovine thrombin and trypsin, respectively.

Primary structure and characterization of a non hemorrhagic metalloproteinase with fibrinolytic activity, from the snake venom of Protobothrops tokarensis (Tokara-habu).

A low molecular weight metalloproteinase, named PT-H2 protease, with fibrinolytic activity, was purified from the venom of Protobothrops tokarensis (Tokara-habu) by gel-filtration using Sephadex G-100, and ion-exchange chromatographies using CM-Sepharose Fast Flow and Mono S HR 5/5. By this procedure, about 85 mg of purified protein were obtained from 1.0 g of P. tokarensis venom. The purified protein showed a single protein band with a molecular weight of about 22.5 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. The pI of purified protein showed a single band of 6.8. This proteinase showed a strong fibrinolytic activity. Further, this proteinase showed fibrinogenase activity and proteolytic activity against synthetic substrates for matrix metalloproteinase, ADAM-17, and TACE (tumor necrosis factor converting enzyme). These proteolytic activities were inhibited by metalloproteinase inhibitors such as EDTA. PT-H2 protease consisted of 201 amino acid residues and had a calculated molecular weight of 22,994.7 Da. This protein showed conservation of the Zn²âº-binding HEXXHXXGXXHD sequence. PT-H2 protease showed high homology from 51.7 to 99.5% with amino acid sequences of other snake venom metalloproteinases.

Purification and characterization of a new platelet aggregation inhibitor with dissociative effect on ADP-induced platelet aggregation, from the venom of Protobothrops elegans (Sakishima-habu).

A platelet aggregation inhibitor, named snake venom platelet aggregation dissociator (SV-PAD)-1, with a dissociative reaction of ADP-induced platelet aggregation, was purified from the venom of Protobothrops elegans (Sakishima-habu) by gel-filtration employing Sephadex G-100, and ion-exchange chromatographies using DEAE-Sepharose Fast Flow, CM-Sepharose Fast Flow, and Mono S. By this procedure, about 1.5mg of purified protein was obtained from 1.0g of P. elegans venom. The purified protein showed a single protein band and the molecular weight was about 110kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. The pI of purified protein showed four-bands of 7.7, 7.8, 7.95, and 8.15. This protein strongly inhibited ADP-induced platelet aggregation in rabbit platelet-rich plasma (PRP), and its IC(50) was about 58nM. It inhibited ristocetin-induced platelet aggregation in rabbit PRP (IC(50): 100nM), but hardly blocked collagen-induced platelet aggregation. This protein promptly dissociated platelet aggregation in rabbit PRP stimulated by high-concentration ADP.