Isolation and characterization of factor X activator from the venom of Vipera aspis aspis

1. A factor X activator was isolated from the venom of Vipera aspis aspis (Aspic viper) by gel filtration and ion-exchange chromatography. 2. The purified activator has a mol. wt of 75,000 and an isoelectric point of 4.6. Upon reduction, this activator migrated as two bands with mol. wts of 16,000 and 14,000 in sodium dodecyl sulfate polyacrylamide gel electrophoresis. 3. The activator from V. a. aspis venom shortened activated partial thromboplastin time (APTT) of normal plasma and factor IX-deficient plasma from humans. 4. Factor X incubated with isolated activator and calcium ions drastically shortened APTT of factor X-deficient plasma and expressed hydrolytic activity against synthetic substrates for factor Xa, however no hydrolytic activity was detected with the activator alone, indicating that the activator converted factor X to the active form.     

Characterization of a new inhibitor for angiotensin converting enzyme from the venom of Vipera aspis aspis

1. Angiotensin converting enzyme inhibitor has been isolated from the venom of Vipera aspis aspis by gel filtration and reverse phase HPLC. 2. The purified inhibitor is a decapeptide, whose amino-terminal is blocked, with mol. wt 1044 determined by fast atom bombardment mass spectrometry. 3. The peptide inhibited the conversion of angiotensin I to angiotensin II, and Ki values were determined to be 7.54 x 10(-4) and 1.36 x 10(-4) M, respectively, using Hip-His-Leu and Hip-Gly-Gly as substrates 4. The peptide also inhibited the degradation of bradykinin, induced hypotension in spontaneously hypertensive rats and caused an increase in capillary permeability in rabbits, however, it possessed no lethality.     

Biological study of muscle degenerating hemorrhagic factor from the venom of Vipera aspis aspis (aspic viper)

1. A hemorrhagic factor was isolated from Vipera a. aspis venom by gel filtration, ion-exchange chromatography and affinity chromatography. 2. Molecular weight of the purified factor was determined to be 67,000 Da, which was composed of 552 amino acid residues. 3. The minimum hemorrhagic dose (MHD) was measured to be 0.11 micrograms per mouse with subcutaneous injection. The hemorrhagic activity was inhibited by chelating agents and reductant. 4. The hemorrhagic factor possesses proteolytic activity against dimethylcasein. 5. Serum creatine phosphokinase level was rapidly increased within 30 min following injections of this preparation into the mice thighs. 6. Actin, one of the main components of muscle fiber, is apparently digested by the hemorrhagic factor. The pathological findings are further reported in this paper.     

Vascular endothelial growth factor VEGF-like heparin-binding protein from the venom of Vipera aspis aspis (Aspic viper).

The heparin-binding dimeric hypotensive factor (HF) was purified from Vipera aspis aspis (Aspic viper) venom [Komori, Y. and Sugihara, H. (1990) Toxicon 28, 359-369]. In this study, the amino acid sequence, and structure and function of HF, were elucidated. By electrospray ionization mass spectrometry (ESI-MS), the molecular weight of HF was determined to be 25 072.1. The complete amino acid sequence of HF was determined by Edman sequencing of the S-pyridylethylated HF and its peptides derived from enzymatic digestion. The theoretical molecular mass calculated from the primary structure agrees well with the molecular weight determined by ESI-MS. HF consists of two homogeneous monomers bound covalently. The monomer with an N-terminal blocked by pyroglutamic acid contains 110 amino acid residues, including eight cysteine residues, two of which are considered to be involved in intermolecular disulfide bonds. Sequential homology search revealed that the primary structure of HF is similar to that of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) with a sequential homology of 45 and 22%, respectively. When injected intradermally into a rat, an increase in capillary permeability was observed with HF or VEGF. On the other hand, only HF exerted a strong hypotensive effect after intravenous injection of samples into a rat. Purified HF has a mitogenic effect on endothelial cells. Through the use of bovine aortic endothelial cells (BAEC), the half-maximal mitogenic concentration of HF was determined to be 5-5. 5 nM (125-138 ng/mL). Similarly, VEGF had a mitogenic concentration at 0.5-1 nM. When incubated with HF and cycloheximide or HF and heparin, the cell growth was inhibited, suggesting that the mechanism of action of HF is similar to that of VEGF.     

Comparative study of three phospholipase A2s from the venom of Vipera aspis

1. Three phospholipase A2s, PLA2-I, PLA2-II and PLA2-III, were isolated from Vipera aspis venom by gel filtration and ion exchange chromatography. 2. Purified PLA2-I, -II and -III have mol. wts of 30,200, 16,000 and 13,500, and isoelectric points of 9.45, 7.65 and less than 4.1, respectively. 3. PLA2-I consists of an acidic subunit (mol. wt 13,700, pI: less than 3.5) and a basic subunit (mol. wt 16,500, pI: 10.6), which can be separated under highly acidic conditions. 4. PLA2-I possessed lethal activity and LD50 for this preparation was estimated to be 0.288 (0.209-0.397) micrograms/g, while lethality was not observed when PLA2-II, -III or each subunit of PLA2-I were administered. 5. Capillary permeability-increasing activity was found in the samples which possessed basic isoelectric points. Additionally, PLA2-I and its basic subunit drastically prolonged activated partial thromboplastin time of platelet rich plasma. 6. Intramuscular injections of PLA2-I, -II and -III increased serum creatine phosphokinase activity in mice, indicating that damage in muscle was caused by these enzymes. 7. NH2-terminal sequences of the three PLA2s were compared with other phospholipase A2s from snake venoms. Furthermore, antigenicities were tested using antiserum prepared against each sample.     

Toxicity evolution of Vipera aspis aspis venom: identification and molecular modeling of a novel phospholipase A(2) heterodimer neurotoxin

Heterodisulfide reductases (HDRs) from methanogenic archaea are iron-sulfur flavoproteins or hemoproteins that catalyze the reversible reduction of the heterodisulfide (CoM-S-S-CoB) of the methanogenic thiol coenzymes, coenzyme M (CoM-SH) and coenzyme B (CoB-SH). In this work, the ground- and excited-state electronic properties of the paramagnetic Fe-S clusters in Methanothermobacter marburgensis HDR have been characterized using the combination of electron paramagnetic resonance and variable-temperature magnetic circular dichroism spectroscopies. The results confirm multiple S=1/2 [4Fe-4S](+) clusters in dithionite-reduced HDR and reveal spectroscopically distinct S=1/2 [4Fe-4S](3+) clusters in oxidized HDR samples treated separately with the CoM-SH and CoB-SH cosubstrates. The active site of HDR is therefore shown to contain a [4Fe-4S] cluster that is directly involved in mediating heterodisulfide reduction. The catalytic mechanism of HDR is discussed in light of the crystallographic and spectroscopic studies of the related chloroplast ferredoxin:thioredoxin reductase class of disulfide reductases.     

Sequences and structural organization of phospholipase A2 genes from Vipera aspis aspis, V. aspis zinnikeri and Vipera berus berus venom. Identification of the origin of a new viper population based on ammodytin I1 heterogeneity.

We used a PCR-based method to determine the genomic DNA sequences encoding phospholipases A2 (PLA2s) from the venoms of Vipera aspis aspis (V. a. aspis), Vipera aspis zinnikeri (V. a. zinnikeri), Vipera berus berus (V. b. berus) and a neurotoxic V. a. aspis snake (neurotoxic V. a. aspis) from a population responsible for unusual neurotoxic envenomations in south-east France. We sequenced five groups of genes, each corresponding to a different PLA2. The genes encoding the A and B chains of vaspin from the neurotoxic V. a. aspis, PLA2-I from V. a. zinnikeri, and the anticoagulant PLA2 from V. b. berus are described here. Single nucleotide differences leading to amino-acid substitutions were observed both between genes encoding the same PLA2 and between genes encoding different PLA2s. These differences were clustered in exons 3 and 5, potentially altering the biological activities of PLA2. The distribution and characteristics of the PLA2 genes differed according to the species or subspecies. We characterized for the first time genes encoding neurotoxins from the V. a. aspis and V. b. berus snakes of central France. Genes encoding ammodytins I1 and I2, described previously in Vipera ammodytes ammodytes (V. am. ammodytes), were also present in V. a. aspis and V. b. berus. Three different ammodytin I1 gene sequences were characterized: one from V. b. berus, the second from V. a. aspis, V. a. zinnikeri and the neurotoxic V. a. aspis, and the third from the neurotoxic V. a. aspis. This third sequence was identical with the reported sequence of the V. am. ammodytes ammodytin I1 gene. Genes encoding monomeric neurotoxins of V. am. ammodytes venom, ammodytoxins A, B and C, and the Bov-B LINE retroposon, a phylogenetic marker found in V. am. ammodytes genome, were identified in the genome of the neurotoxic V. a. aspis. These results suggest that the population of neurotoxic V. a. aspis snakes from south-east France may have resulted from interbreeding between V. a. aspis and V. am. ammodytes.