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At least 109 records · Page 6Linked to original sources

PubMed1984

Release of slow reacting substance from the guinea-pig lung by phospholipases A2 of Vipera russelli snake venom.

Phospholipases A2 (PLA2) of Vipera russelli venom were isolated by column chromatography. The ability of PLA2 fractions to release slow reacting substance (SRS) was studied in the guinea-pig lung perfused with Krebs' solution. The relationship between the perfusion pressure change produced by PLA2 and SRS release was also studied. Two PLA2 fractions (II-5 and III-3; 3-100 micrograms), injected into the lung increased the perfusion pressure and released SRS. Pretreatment of the lung with indomethacin (10 micrograms) reduced the pressure response induced by the PLA2 fractions. The SRS released in the lung effluent by PLA2 was identified by bioassay as a mixture of thromboxane A2 (TXA2), prostacyclin (PGI2) and leukotrienes. TXA2 and PGI2 release was also quantitated by radioimmunoassay of the degradation products TXB2 and 6-keto-PGF1 alpha, respectively. There was a positive linear correlation between the pressure increases and the ratios of TXB2 to 6-keto-PGF1 alpha (r = 0.87). It appears that the relative amounts of TXA2 and PGI2 released determine the effects of PLA2 fractions on the guinea-pig lung. The release of arachidonic acid metabolites, prostaglandins and leukotrienes may account for part of the hypotensive action of PLA2.

6-Ketoprostaglandin F1 alpha↗

PubMed1985

A platelet function inhibitor purified from Vipera russelli siamensis (Smith) snake venom.

By means of CM-Sephadex C-50 column chromatography and gel filtration on Sephadex G-75, a potent platelet function inhibitor was purified from Vipera russelli siamensis venom. It appeared as a single protein band on polyacrylamide gel electrophoresis in the presence or absence of SDS, and consists of 123 amino acid residues. Its NH2-terminal residue is serine. It showed the following characteristics: molecular weight, 13,800; isoelectric point, 10.4; LD50, 0.5 +/- 0.12 mg/kg (i.v.). The platelet inhibitor exhibited phospholipase A2 activity with a specific activity of 35 mumoles/min/mg. From 2 g of the venom, 70 mg of the purified inhibitor was obtained. Inhibition of human platelet aggregation induced by ADP or adrenaline was dose-dependent, with ID50 of 1.14 micrograms/ml or 0.37 microgram/ml, respectively. The platelet aggregation induced by thrombin or collagen was also inhibited and the inhibitory activity on platelet aggregation was heat stable (at 100 degrees C, 20 min) in an acidic medium (pH 5.8), while its phospholipase A2 activity was relatively heat labile under the same condition. The release of 3H-serotonin in platelets stimulated by ADP was also inhibited and this was positively correlated with inhibition of platelet aggregation induced by ADP (r = 0.998, P less than 0.002).

Amino Acids↗

PubMed1986

Gel permeation patterns of venoms from eleven species of the genus Vipera.

Gel filtration of venoms from eleven species of the genus Vipera shows similar patterns on Sephadex G-75, with three groups of protein peaks. The second group, which contains phospholipase A2, is variable among the species. As found in some other viperids, the venom of V. bornmuelleri shows synergism between phospholipase A and other fractions that considerably increases lethal potency.

Animals↗

PubMed1986

Isolation and characterization of a proteolytic factor from the venom of Vipera palaestinae.

A proteolytic enzyme which is active on collagen and gelatin was isolated from the venom of Vipera palaestinae. The enzyme showed an optimal temperature of 45 degrees C and an optimal pH of 8.0. It was inhibited by snake blood serum, but not by EDTA or trypsin inhibitors. The enzyme was completely separated from one of the venom hemorrhagins, which accompanied it through the purification procedure. The possible evolution of hemorrhagins from proteolytic enzymes is discussed.

Achilles Tendon↗

PubMed1986

Effect of Russell's viper (Vipera russelli siamensis) venom on renal hemodynamics in dogs.

The effect on renal hemodynamics of Russell's viper (Vipera russelli siamensis) venom was studied in 8 mongrel dogs. The venom (0.10 mg/kg) was injected i.v. Measurements of general circulation and renal function were carried out over 48 hr. During the initial post-injection period, mean arterial blood pressure, pulse pressure and heart rate decreased. Total peripheral vascular resistance and renal vascular resistance showed a tendency to increase. There was no change in cardiac output. Thereafter the blood pressure and heart rate returned to the control level 2 hr after injection and remained stable throughout the experiment. The cardiac output remained unchanged, but the pulse pressure later increased. Renal blood flow, glomerular filtration rate, renal fraction and the rate of urine flow were decreased 24 hr after venom injection and rose to the control levels at 48 hr. Renal vascular resistance remained relatively increased, while peripheral resistance decreased, at 24 hr. Blood volume was unchanged throughout the 48 hr. Disseminated intravascular coagulation was not observed, although the clotting time was prolonged. Renal histological studies showed no remarkable changes; tubular necrosis was not seen. The renal hemodynamic changes may initially be due to catecholamine release and later to renin - angiotensin activation with renal vasoconstriction.

Animals↗

PubMed1987

Interaction of phospholipase A2 from Vipera russelli venom with aristolochic acid: a circular dichroism study.

The interaction of aristolochic acid, an alkaloid from Aristolochia species, with phospholipase A2 (PLA2) from Vipera russelli venom was followed by circular dichroism measurements. Aristolochic acid is a non-competitive inhibitor of PLA2. The binding of aristolochic acid to PLA2 induces an extrinsic CD band at 320 nm. The association constant was determined by following the intensity of the extrinsic CD band. Aristolochic acid forms a 1:1 complex with PLA2, with an association constant K, of 5.4 X 10(3) M-1 and a Gibb's free energy change (delta G0) for the reaction of -5.1 kcal/mole. The values of association constant and delta G0 suggest that the interaction is weak. Binding of aristolochic acid causes a change in the secondary structure of the protein which is characterized by an increase in the apparent content of alpha-helix, without any detectable change in the tertiary structure of PLA2.

Aristolochic Acids↗

PubMed1988

Kinetics of envenomation with Russell's viper (Vipera russelli) venom and of antivenom use in mice.

The kinetics of I125-labelled venom and antivenom of Russell's viper (Vipera russelli) were determined following i.v. administration in mice. The kinetic profiles follow a two-compartment open model with mean distribution half-lives of 15.93 and 15.36 min, and mean elimination half-lives of 8.88 and 5.37 hr for venom and antivenom, respectively. Antivenom follows closely that of venom in its mode of distribution while its elimination is almost twice as fast as that of venom. The steady-state distribution ratio between blood and tissue indicates a greater affinity of the venom to the tissues as compared to antivenom. The primary route of elimination of venom and antivenom or their degraded products was via the urine. Small amounts of trichloroacetic acid-precipitable radioactivity and radioimmunoassayable venom and antivenom recovered in the urine suggest that very little intact venom or antivenom was excreted in the urine. Kinetic studies using unlabelled venom produced values comparable to those obtained with the labelled venom. The results emphasize the importance of maintaining optimal serum antivenom levels, by timely and repeated administration instead of a single bolus dose, in the management of snake envenoming.

Animals↗

PubMed1988

Geographical variation in India in the composition and lethal potency of Russell's viper (Vipera russelli) venom.

Venom samples of Russell's viper (Vipera russelli) from three localities in India were analysed for their composition and toxicity. Column chromatographic fractionation on CM-Sephadex C-25 showed the absence of three fractions in the venom samples of southern India compared with the samples from northern and western India. The SDS-PAGE pattern of southern Indian venom samples also showed lack of three protein bands corresponding to molecular weights of 66,000, 39,000 and 9000. Venom samples from northern and western India possessed high acidic phospholipase activity while acidic phospholipase activity was absent in the samples from southern India, which in contrast showed large basic fractions with phospholipase activity. Proteolytic activity was present in all the venom samples; however, this activity, as well as trypsin inhibitor activity, was very low in the southern Indian samples. The ratio of proteolytic activity to inhibitor activity remained constant in most of the venom samples studied. LD50 values for most of the venom samples from northern and western India were twice as high as that of the samples from southern India. High phospholipase activity correlated with high lethal potency in the venom samples studied.

Animals↗

PubMed1988

Purification and partial biochemical characterization of an edema inducing phospholipase A2 from Vipera russelli (Russell's viper) snake venom.

A phospholipase A2 (VRV PL-VI) from Vipera russelli venom was purified to homogeneity in a single step on CM-Sephadex C-25 column. VRV PL-VI is a basic protein with a mol. wt of about 12,000 and showed a basic pH optimum and a high temperature maximum. It hydrolysed purified phospholipids in the order of phosphatidylethanolamine greater than phosphatidylcholine much greater than phosphatidylserine greater than phosphatidylinositol = 0. It is toxic with an LD50 value (i.p.) of 3.5 micrograms/g body weight in mice and it induced persistent edema in the mouse foot pad.

Animals↗

PubMed1988

Physiological and biochemical properties of a kallikrein-like enzyme from the venom of Vipera aspis aspis (aspic viper).

A kallikrein-like enzyme was isolated from the venom of Vipera aspis aspis by Sephadex G-75, Q-Sepharose and Heparin-Sepharose CL-6B column chromatography. The purified enzyme is a glycoprotein with a mol. wt of 43,000 and an isoelectric point of 4.1. The enzyme possesses arginine ester hydrolase activity, but no proteolytic activity against either dimethylcasein or fibrinogen. The reaction mixture of the enzyme and bovine plasma induced contraction of the isolated rat uterus, suggesting that the enzyme releases kinin from the plasma constituent. The amount of enzyme, which releases an equal amount of kinin corresponding to 1 nmole of bradykinin per min, is 2.36 mg. Additionally, the kallikrein-like enzyme demonstrated capillary permeability-increasing activity and hypotensive activity. A synthetic kininogen analog, Ser-Leu-Met-Lys-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg-Ser-Val-Gln-Val-Ser, was cleaved by the enzyme to release bradykinin and kallidin, also indicating that the enzyme has a kallikrein-like activity. Uterine contraction, capillary permeability-increasing activity and arginine ester hydrolase activity were inhibited by diisopropyl fluorophosphate, suggesting that the serine hydroxyl group is essential for enzymatic and biological activities. Antithrombin III and heparin, serine-protease inhibitors found in plasma had no inhibitory effect on these activities of the purified enzyme. The amino acid sequence of the NH2 terminal region of the enzyme has similarities with kallikrein-like enzymes from other snake venoms and with porcine pancreatic kallikrein.

Amino Acids↗

PubMed1989

Dissociation of catalytic activity and neurotoxicity of a basic phospholipase A2 from Russell's viper (Vipera russelli) venom.

A neurotoxic phospholipase A2, VRV PL-V was purified from Vipera russelli venom in a single step by CM-Sephadex C-25 column chromatography. VRV PL-V is a basic PLA2 with a mol. wt of approximately 10,000. The lethal potency of VRV PL-V was greater than that of the crude V. russelli venom. VRV PL-V showed anticoagulant activity and induced edema in the foot pad of the mouse. VRV PL-V undergoes aggregation at pH 4.8. The size of the aggregate increased as the temperature at which the enzyme was incubated was raised. A highly aggregated form with a mol. wt of 53,100 was formed at 96 degrees C. This aggregate showed a two-fold increase in its catalytic activity, while its neurotoxic activity disappeared. The aggregate also showed a significant increase in its anticoagulant activity when compared to the monomeric form. Edema-inducing activity decreased upon association to higher molecular form.

Anticoagulants↗

PubMed1989

Purification and characterization of a major phospholipase A2 from Russell's viper (Vipera russelli) venom.

A major phospholipase A2 (VRV PL-VIIIa) which constitutes 24% of the whole Vipera russelli venom was purified to homogeneity by CM-Sephadex C-25 column chromatography followed by gel filtration on Sephadex G-50. VRV PL-VIIIa is a basic protein with a molecular weight of 11,800 by SDS-PAGE. This enzyme contributes 45% of the total PLA2 activity of the venom, but it is least toxic compared to other purified basic PLA2 enzymes prepared from V. russelli venom. The LD50 value (i.p.) of VRV PL-VIIIa is 5.3 mg/kg body wt. It shows neurotoxic symptoms and damages vital organs such as lung, liver and kidney at LD50 doses. It induces myonecrosis when injected i.m. into the thigh muscle of mice and edema when injected into the foot pads.

Animals↗

PubMed1989

Origin and function of supporting cells in the venom glands of the lesser weeverfish (Trachinus vipera).

Supporting cells in the venom glands of Trachinus vipera form a network whose meshes are filled with developed glandular cells. These supporting cells are derived from epidermal cells. A connective tissue sheath forms inside the gland, separating it into pockets. A basal lamina surrounding the pockets between the connective tissue and supporting cells can be observed similar to that between connective tissue and epidermis. The pockets are probably formed by epidermal invagination. In view of the ultrastructural observations, the supporting cells not only maintain the cohesiveness of the venom gland, as demonstrated by the presence of numerous interdigitations and desmosomes, but may also play a role in the regeneration of large glandular cells.

Animals↗

PubMed1990

Synergistic interaction of a protease and protease inhibitors from Russell's viper (Vipera russelli) venom.

An acidic proteolytic enzyme, RVVX, was purified from Vipera russelli venom by successive chromatography on CM-Sephadex C-25, DEAE-cellulose and Sephadex G-100 columns. RVVX is a glycoprotein with a mol. wt of 79,000. It exhibited caseinolytic and factor X activating properties. Two trypsin inhibitors, TI-I and TI-II, were purified from V. russelli venom in a single step by CM-Sephadex C-25 column chromatography. The trypsin inhibitors interacted with the proteolytic enzyme RVVX. TI-I inhibited only the factor X activating property of RVVX while TI-II inhibited both, the caseinolytic and also factor X activating properties of RVVX. The edema inducing activity of RVVX increased markedly in the presence of non-edema inducing doses of TI-I and TI-II. RVVX, TI-I and TI-II were non-lethal in mice. The combination of RVVX and TI-II demonstrated enhanced toxicity.

Animals↗

PubMed1990

Purification and physiological study of a hypotensive factor from the venom of Vipera aspis aspis (aspic viper).

A hypotensive factor was isolated from the venom of Vipera aspis aspis by Sephadex G-75, S-Sepharose column chromatography, and reverse phase HPLC using a Develosil 300 ODS-7 column. The purified factor was a basic protein with a mol. wt of 25,000 and an isoelectric point of 7.95. Intravenous injection of hypotensive factor induced an immediate fall in blood pressure of rats, whose duration depended on the dose employed. The hypotensive response was not affected by dithiothreitol, beta-mercaptoethanol, EDTA, p-tosyl-L-phenylalanine chloromethylketone, p-chloromercuribenzoic acid, or diisopropyl fluorophosphate, and was resistant to heat-treatment at 100 degrees C for 30 min, however, it disappeared after incubation with antivenom prepared against the hypotensive factor. The factor is devoid of proteinase, esterase, phospholipase A2 and kallikrein-like activities, and lethal, hemorrhagic and capillary permeability increasing activities are also absent. Compared to the hypotension induced by the hypotensive factor in normotensive rats, a more potent response was observed when it was administered to 11-week-old spontaneously hypertensive rats.

Amino Acids↗

PubMed1991

Beta-fibrinogenase from the venom of Vipera lebetina.

An arginine esterase was purified from the venom of Vipera lebetina by gel filtration on Sephadex G-100 and by affinity and DEAE-cellulose chromatography. The enzyme has a mol. wt of 52,500 and pI approximately 3. It is a glycoprotein containing 23% of neutral sugars, and has extremely high thermostability. The esterase activity is inhibited by diisopropylfluorophosphate (DFP) and phenylmethylsulfonyl fluoride (PMSF). The Km and kcat values are for alpha-N-benzoyl-L-arginine ethyl ester (BAEE) 7.7 x 10(-5) M and 43.8 sec-1, for p-tosyl-L-arginine methyl ester (TAME) 3.6 x 10(-4) M and 39.8 sec-1 (pH 8.5, 25 degrees C, and for alpha-N-benzoyl-DL-arginine-4-nitroanilide (BAPNA) 1.8 x 10(-4) M and 0.94 sec-1 (pH 8.3, 25 degrees C), respectively. Lysine esters are not hydrolyzed. The enzyme has weak caseinolytic activity and hydrolyzes glucagon at the sites Lys12-Tyr13, Arg17-Arg18 and Arg18-Ala19. In fibrinogen it cleaves B beta-chain first and later also the A alpha-chain.

Amino Acid Sequence↗

PubMed1991

Effects of chemical modification on enzymatic and toxicological properties of phospholipases A2 from Naja naja naja and Vipera russelli snake venoms.

The effects of chemical modification with 4-NN-dimethyl amino azo benzene-4'-isothiocyanate on various biological activities of phospholipases A2, NN-XIII-PLA2 from Naja naja naja and VRV-PL-VIIIa from Vipera russelli snake venoms were investigated. Modification of the enzymes resulted in significant reduction of lethal, hemolytic, anticoagulant and enzymatic activities. The Km value of the modified enzymes was increased. The modified enzymes failed to induce edema in the foot pads of mice and were non-lethal up to 16 mg/kg body weight. However, considerable myotoxicity was retained, suggesting that the toxins have multiple sites for biological activities. The aggregated form obtained from modified NN-XIII-PLA2 exhibited decreased enzymatic activity and increased toxicity compared to the modified monomer. This aggregated form did not show pyrophosphatase/phosphomonoesterase activity in contrast to the aggregated form obtained from the native NN-XIII-PLA2 molecule.

Alkaline Phosphatase↗

PubMed1991

Purification and characterization of a fibrinogenase from Vipera lebetina (desert adder) venom.

A fibrinogenase from Vipera lebetina venom was isolated by gel filtration in a Superose 12 column prep grade HR 16/50 and by ion-exchange in a Mono Q HR 5/5 column. The purified enzyme, which was obtained with a yield of 8 mg from 60 mg of crude venom, is a glycoprotein having an isoelectric point of 5.9 +/- 0.1 and a mol. wt of 26,000 +/- 1000 as estimated by SDS-PAGE. The biochemical characterization of the enzyme revealed that it hydrolyzes readily the B beta chain of fibrinogen and the A alpha chain as well as fibrin and casein. Over a pH range from 4 to 11 the enzyme was not inactivated by a 20 min treatment at 90 degrees C. The isolated fibrinogenase is inhibited by ethylenediamine tetraacetic acid, dithiothreitol and L-cysteine but not by phenylmethylsulfonyl fluoride. On the other hand, it is activated by Ca2+ and Mg2+. Purified fibrinogenase up to a dose of 100 micrograms/mouse shows no toxicity and has no hemorrhagic activity.

Animals↗