Evidence for heterogeneous forms of the snake venom metalloproteinase jararhagin: a factor contributing to snake venom variability

The reprolysin subfamily of metalloproteinases includes snake venom metalloproteinases (SVMP) and mammalian disintegrin/metalloproteinase. These proteins are synthesized as zymogens and undergo proteolytic processing resulting in a variety of multifunctional proteins. Jararhagin is a P-III SVMP isolated from the venom of Bothrops jararaca. In crude venom, two forms of jararhagin are typically found, full-length jararhagin and jararhagin-C, a proteolytically processed form of jararhagin that is composed of the disintegrin-like and cysteine-rich domains of jararhagin. To better understand the structural and mechanistic bases for these forms of jararhagin in the venom of B. jararaca and the source of venom complexity in general, we have examined the jararhagin forms isolated from venom and the autolysis of isolated jararhagin under the conditions of varying pH, calcium ion concentration, and reducing agents. From our results, jararhagin isolated from venom appears as two forms: a predominant form that is stable to in vitro autolysis and a minor form that is susceptible to autolysis under a variety of conditions including alkaline pH, low calcium ion concentrations, or reducing agent. The autolysis site for production of jararhagin-C from isolated jararhagin was different from that observed for jararhagin-C as isolated from crude venom. Taken together, these data lead us to the conclusion that during the biosynthesis of jararhagin in the venom gland at least three forms are present: one form which is rapidly processed to give rise to jararhagin-C, one form which is resistant to processing in the venom and autolysis in vitro, and one minor form which is susceptible to autolysis under conditions that promote destabilization of its structure. The presence of these different forms of jararhagin contributes to greater structural and functional complexity of the venom and may be a common feature among all snake venoms. The biological and biochemical features in the venom gland responsible for these jararhagin isoforms are currently under investigation.     

Identification of essential residues within Lit, a cell death peptidase of Escherichia coli K-12

Bacteriophage exclusion is a suicide response to viral infection. In strains of Escherichia coli K-12 infected with T4 phage this process is mediated by the host-encoded Lit peptidase. Lit is activated by a unique sequence in the major head protein of the T4 phage (the Gol sequence) which then cleaves site-specifically the host translation factor EF-Tu, ultimately leading to cell death. Lit has very low sequence identity with other peptidases, with only a putative metallopeptidase motif, H(160)EXXH, giving an indication of its catalytic activity. The aim of the present study was to ascertain if Lit is a metallopeptidase, identify residues essential for Lit activity, and probe the involvement of the Gol sequence in the activation of enzymatic activity. Lit activity was inhibited by the zinc chelator 1,10-phenanthroline, consistent with the suggestion that it is a metallopeptidase. Preliminary covalent modification experiments found that Lit was susceptible to inactivation by diethyl pyrocarbonate, with about three histidines reversibly modified, one of which was found to be essential for proteolytic activity. Subsequently, 13 mutants of the Lit enzyme were constructed that included all 10 histidines as well as other residues within the metallopeptidase motif. This demonstrated that the residues within the HEXXH motif are required for Lit activity and further defined the essential catalytic core as H(160)EXXHX(67)H, with additional residues such as His169 being important but not essential for activity. Kinetic analysis of Lit activation by a synthetic Gol peptide highlighted that elevated concentrations of the peptide (>10-fold above activation K(M)) are inhibitory to Lit, with this effect also seen in partially active Lit mutants. The susceptibility of Lit to inhibition by its own activating peptide suggests that the Gol sequence may be able to bind nonproductively to the enzyme at high concentration. We discuss these data in the context of the currently understood models for Gol-mediated activation of the Lit peptidase and its mechanism of action.     

Inhibition of ClC-2 Chloride Channels by a Peptide Component or Components of Scorpion Venom

ClC chloride channels play essential roles in membrane excitability and maintenance of osmotic balance. Despite the recent crystallization of two bacterial ClC-like proteins, the gating mechanism for these channels remains unclear. In this study we tested scorpion venom for the presence of novel peptide inhibitors of ClC channels, which might be useful tools for dissecting the mechanisms underlying ClC channel gating. Recently, it has been shown that a peptide component of venom from the scorpion L. quinquestriatus hebraeus inhibits the CFTR chloride channel from the intracellular side. Using two-electrode voltage clamp we studied the effect of scorpion venom on ClC-0, -1, and -2, and found both dose- and voltage-dependent inhibition only of ClC-2. Comparison of voltage-dependence of inhibition by venom to that of known pore blockers revealed opposite voltage dependencies, suggesting different mechanisms of inhibition. Kinetic data show that venom induced slower activation kinetics compared to pre-venom records, suggesting that the active component(s) of venom may function as a gating modifier at ClC-2. Trypsinization abolished the inhibitory activity of venom, suggesting that the component(s) of scorpion venom that inhibits ClC-2 is a peptide.     

The action of venom and proteolytic enzymes on the non-specific inhibitor of hyaluronidase

1. It has been shown that a number of proteolytic enzymes and snake venom, in relatively small amounts, and within a wide range of pH variation, will restore hyaluronidase activity after its inhibition by serum. 2. The known properties of the venom protease are found to be identical with those of Haas' "proinvasin I." It is concluded that the protease of the venom offers adequate explanation for the effects previously attributed to "proinvasin I." 3. Proteolytic activity is found in hyaluronidase preparations of bovine origin and is considered to be responsible for the reversal of inhibition of hyaluronidase by serum.     

Possible association of Neu2 with plasma membrane fraction from mouse thymus exhibited sialidase activity with fetuin at pH 7.0 but not at pH 4.5

Compared to other organs, the mouse thymus exhibits a high level of sialidase activity in both the soluble and crude membrane fractions, as measured at neutral pH using 4MU‐Neu5Ac as a substrate. The main purpose of the present study was to identify the sialidase with a high level of the activity at neutral pH in the crude membrane. Several parameters were analyzed using the soluble (S) fraction, N and D fractions that were obtained by NP‐40 or DOC/NP‐40 solubilization from the thymus crude membrane. The main sialidase activity in the N fraction exhibited almost the same pI as that of soluble Neu2 and 60% of the activity was removed from the membrane by three washes with 10 mM Tris‐buffer, at pH 7.0. The N fraction preferentially hydrolyzed the sialic acid bond of glycoprotein and exhibited sialidase activity with fetuin at pH 7.0 but not at pH 4.5. The same activity was observed in a plasma membrane‐rich fraction. To date, the removal of sialic acid from fetuin at pH 7.0 was reported only with soluble Neu2 and the membrane fraction from Neu2‐transfected COS cells. We analyzed the gene that controls the sialidase activity in the crude membrane fraction at pH 7.0 using SMXA recombinant mice and found that compared with other three genes, Neu2 presented the best correlation with the activity level. We suggest that Neu2 is most likely responsible for the main activity in the N fraction, due to its association with the membrane by an unknown mechanism.     

Transthyretin is a metallopeptidase with an inducible active site

TTR (transthyretin) was found recently to possess proteolytic competency besides its well-known transport capabilities. It was described as a cryptic serine peptidase cleaving multiple natural substrates (including β-amyloid and apolipoprotein A-I) involved in diseases such as Alzheimer's disease and atherosclerosis. In the present study, we aimed to elucidate the catalytic machinery of TTR. All attempts to identify a catalytic serine residue were unsuccessful. However, metal chelators abolished TTR activity. Proteolytic inhibition by EDTA or 1,10-phenanthroline could be reversed with Zn2+ and Mn2+. These observations, supported by analysis of three-dimensional structures of TTR complexed with Zn2+, led to the hypothesis that TTR is a metallopeptidase. Site-directed mutagenesis of selected amino acids unambiguously confirmed this hypothesis. The TTR active site is inducible and constituted via a protein rearrangement resulting in ~7% of proteolytically active TTR at pH?7.4. The side chain of His88 is shifted near His90 and Glu92 establishing a Zn2+-chelating pattern HXHXE not found previously in any metallopeptidase and only conserved in TTR of humans and some other primates. Point mutations of these three residues yielded proteins devoid of proteolytic activity. Glu72 was identified as the general base involved in activation of the catalytic water. Our results unveil TTR as a metallopeptidase and define its catalytic machinery.     

Studies on the cholinesterases inhibiting compounds from the Cassiopea andromeda venom

Cholinesterase inhibitors find application in the combat and care of several diseases, especially AD. Jellyfish venoms are the most promising sources of potent cholinesterase inhibitors. Therefore, it is of interest to study cholinesterases inhibiting compounds from the Cassiopea andromeda venom. We report bioactive compounds using the GC-MC method followed by molecular modeling and docking data analysis. The GC-MS analysis of the crude venom led to the identification of seven bioactive compounds (C1-C7), comprising the steroidal alkaloids, phenolic and carotenoid derivatives. The venom exhibited inhibitory activities against the cholinesterase enzymes. The compound C2, a Dioxolane steroid, displayed the strongest inhibition on both AChE and BChE activities for further consideration.     

Venom from Anemesia species of spider modulates high voltage-activated Ca(2+) currents from rat cultured sensory neurones and excitatory post synaptic currents from rat hippocampal slices

The actions of crude venom from Anemesia species of spider were investigated in cultured dorsal root ganglion neurones from neonatal rats and hippocampal slices. Using mass spectrometry (MALDI-TOF MS), 10-12 distinct peptides with masses between about 3 and 10kDa were identified in the crude spider venom. At a concentration of 5 microg/ml crude Anemesia venom transiently enhanced the mean peak whole cell voltage-activated Ca(2+) current in a voltage-dependent manner and potentiated transient increases in intracellular Ca(2+) triggered by 30mM KCI as measured using Fura-2 fluorescence imaging. Additionally, 5-8 microg/ml Anemesia venom increased the amplitude of glutamatergic excitatory postsynaptic currents evoked in hippocampal slices. Omega-Conotoxin GVIA (1 microM) prevented the increase in voltage-activated Ca(2+) currents produced by Anemesia venom. This attenuation occurred when the cone shell toxin was applied before or after the spider venom. Anemesia venom (5 microg/ml) created no significant change in evoked action potentials but produced modest but significant inhibition of voltage-activated K(+) currents. At a concentration of 50 microg/ml Anemesia venom only produced reversible inhibitory effects, decreasing voltage-activated Ca(2+) currents. However, no significant effects on Ca(2+) currents were observed with a concentration of 0.5 microg/ml. The toxin(s) in the venom that enhanced Ca(2+) influx into sensory neurones was heat-sensitive and was made inactive by boiling or repetitive freeze-thawing. Boiled venom (5 microg/ml) produced significant inhibition of voltage-activated Ca(2+) currents and freeze-thawed venom inhibited Ca(2+) transients measured using Fura-2 fluorescence. Our data suggest that crude Anemesia venom contains components, which increased neuronal excitability and neurotransmission, at least in part this was mediated by enhancing Ca(2+) influx through N-type voltage-activated Ca(2+) channels.     

Inhibition of mitochondrial creatine kinase activity by D-2-hydroxyglutaric acid in cerebellum of young rats

D-2-Hydroxyglutaric aciduria (DHGA) is a neurometabolic disorder biochemically characterized by tissue accumulation and excretion of high amounts of D-2-hydroxyglutaric acid (DGA). Although the affected patients have predominantly severe neurological findings, the underlying mechanisms of brain injury are virtually unknown. In previous studies we have demonstrated that DGA, at concentrations as low as 0.25 mM, significantly decreased creatine kinase activity and other parameters of energy metabolism in cerebral cortex of young rats. In the present study, we investigated the effect of DGA (0.25-5 mM) on total creatine kinase (tCK) activity, as well as on CK activity in cytosolic (Cy-CK) and mitochondrial (Mi-CK) preparations from cerebellum of 30-day-old Wistar rats in order to test whether the inhibitory effect of DGA on CK was tissue specific. We verified that tCK (22% inhibition) and Mi-CK (40% inhibition) activities were moderately inhibited by DGA at concentrations of 2.5 mM and higher, in contrast to Cy-CK, which was not affected by the acid. Kinetic studies revealed that the inhibitory effect of DGA was non-competitive in relation to phosphocreatine. We also observed that this inhibition was fully prevented by preincubation of the homogenates with reduced glutathione, suggesting that the inhibition of CK activity by DGA is possibly mediated by modification of essential thiol groups of the enzyme. Our present results therefore demonstrate a relatively weak inhibitory effect of DGA on cerebellum Mi-CK activity, as compared to that provoked in cerebral cortex, and may possibly be related to the neuropathology of DHGA, characterized by cerebral cortex abnormalities.     

Possible mechanism of the protective effect of phosphocreatine on the ischemic myocardium

The uptake of 32P-phosphocreatine by control and ischemic isolated perfused rat hearts has been studied. The rate of phosphocreatine (PCr) uptake by the hearts after 35 minutes of ischemia was two times that in control hearts at 0.5-10 mM PCr in the perfusate. At 10 mM PCr in the perfusate, this rate was 182 nmoles/min/g dry weight. The 5'-nucleotidase and phosphatase activities were found in the crude plasma membrane fraction of rat heart. The pH-dependence of these enzymes was examined. The 5'-nucleotidase activity decreased with a drop in pH from 8.0 to 6.0. The phosphatase activity in the crude plasma membrane fraction of rat heart was increased 2-fold with a decrease in pH from 8.0 to 6.0. The 5'-nucleotidase activity was inhibited by 10 mM PCr in the presence of 5 mM Mg2+. This inhibition was pH-dependent with a maximum (58%) at pH 6.0. The inhibition of phosphatase activity by PCr was independent of pH and reached 20% in the presence of 10 mM PCr. Some feasible mechanisms of the protective effect of PCr on ischemic myocardium are discussed.     

Beta-fibrinogenase from the venom of Agkistrodon p. piscivorus

1. Beta-fibrinogenase was isolated from the venom of Agkistrodon p. piscivorus by column chromatography on Sephadex G-100, DEAE-Sephacel and by chromatofocusing, with a yield of 2.5 mg of purified enzyme from 1 g of crude venom. 2. The enzyme was homogeneous by SDS and non-SDS disc electrophoresis on polyacrylamide gel at pH 8.3. 3. Beta-fibrinogenase is a glycoprotein possessing both TAME hydrolase and kinin-releasing activities. 4. A mol. wt of approximately 33,500 and an isoelectric point 4.5 was determined. 5. The enzyme is stable to heat treatment and to a pH range of 2-10. 6. Beta-fibrinogenase activity is inactivated by DFP, suggesting that serine is involved in the enzymatic activity. 7. The Michaelis constant (Km) of this enzyme for TAME and inhibition constant (Ki) for DFP were found to be 7.04 X 10(-3) and 4.13 X 10(-3) M, respectively.     

Calmodulin and troponin C: a comparative study of the interaction of mastoparan and troponin I inhibitory peptide [104-115]

Recent studies using bee and wasp venom peptides have led to the hypothesis that proper complex formation with calmodulin (CaM) requires the presence of a basic amphiphilic helix on the surface of the target protein [Cox, J. A. (1984) Fed. Proc., Fed. Am. Soc. Exp. Biol. 43, 3000]. We have tested this hypothesis by examining CaM and troponin C (TnC) complex formation with two basic peptides, the wasp venom tetradecapeptide mastoparan and the physiologically relevant synthetic troponin I (TnI) inhibitory peptide [104-115], using far-ultraviolet circular dichroism as a secondary structure probe. Complex formation between mastoparan and either CaM or TnC results in an increase in helical content, whereas the helical content of TnI inhibitory peptide does not increase when bound to either protein. Significantly, mastoparan is 78% alpha-helical in a 50% solution of the helix-inducing solvent trifluoroethanol and has a high helix-forming potential according to the Chou-Fasman rules while TnI inhibitory peptide contains none and is not predicted to have any. We interpret these data as indicating that these peptides exhibit substantially different secondary structures upon binding to CaM or TnC. The ability of mastoparan to regulate the acto-subfragment 1-tropomyosin ATPase has also been examined. Mastoparan and TnI inhibitory peptide inhibited 31% and 45% of the activity, respectively. TnC and CaM promote differing degrees of Ca2+-sensitive release of inhibition by both peptides. Sequence comparison suggests that the basic residues present in both peptides are important for binding. However, we conclude that an alpha-helical structure is not a prerequisite for the binding of target proteins to CaM and TnC.     

Inhibition of enzymatic and pharmacological activities of some snake venoms and toxins by Mandevilla velutina (Apocynaceae) aqueous extract

Phospholipases A(2) (PLA(2)) are multifunctional proteins which exhibit varied biological activities correlated to the structural diversities of the sub-classes. The crude aqueous extract from subterranean system of Mandevilla velutina, a plant found in Brazilian savanna, was assayed for its ability to inhibit biological activities of several snake venoms and isolated PLA(2)s. The extract induced total inhibition of the phospholipase activity of Crotalus durissus terrificus venom and only partial inhibition of Bothrops venoms. When assayed against purified toxins, the highest efficacy was detected against CB and crotoxin, while almost ineffective against PLA(2)s from the genus Bothrops. Although M. velutina crude extract significantly inhibited the myotoxic activity of C. d. terrificus venom and CB, it produced only partial inhibition of either Bothrops jararacussu venom or its main myotoxins BthTX-I (basic Lys49), BthTX-II (basic Asp49) and BthA-I-PLA(2) (acidic Asp49). The extract exhibited also full inhibition of hemorrhage caused by Bothrops alternatus, Bothrops moojeni and Bothrops pirajai snake venoms, but partial inhibition (90%) of that induced by B. jararacussu venom. The extract was ineffective to inhibit the fibrinogenolytic activity of B. moojeni, B. alternatus and B. pirajai crude venoms, while their caseinolytic activity was only partially inhibited. No inhibition of the anticoagulant activity, although partial reduction of the edema-inducing activity of C. d. terrificus and B. alternatus crude venoms, CB, PrTX-I, BthTX-I and crotoxin was observed. Besides extending survival of mice injected with lethal doses of C. d. terrificus and B. jararacussu venoms, M. velutina extract decreased to 50% the lethality of mice. Extracts of 18 month old micropropagated plants were able to partially neutralize the effect of the crude venoms and toxins.     

High molecular mass kininogen inhibits metalloproteinases of Bothrops jararaca snake venom

High molecular mass kininogen (HK) purified from Bothrops jararaca (Bj) plasma was tested on activities of the Bj venom in vivo and in vitro. Results showed that, when incubated with BjHK, the Bj venom presented inhibition on hemorrhagic, edema forming, myotoxic, and coagulant activities. It is well known that metalloproteinases are directly or indirectly involved in these activities. Similarly, human HK inhibits the hemorrhagic effect of the Bj venom as well as hemorrhagic and enzymatic effects of jararhagin, a hemorrhagic metalloproteinase isolated from Bj venom. Complex between HK and jararhagin was not detected by gel filtration. Nevertheless, the inhibitory effect of the hemorrhagic activity of the venom was only partial when HK was pre-incubated with 0.4mM ZnCl(2) or with 0.45mM CaCl(2). These data suggest that the inhibitory effect depends, at least partially, on the competition for ions between kininogen and metalloproteinases of the venom.     

Superantigen profiles of emm and emm-like typeable and nontypeable pharyngeal streptococcal isolates of South India

Background

Toxins derived from jellyfishes have been exploited as a model for the development of new drug promising applications to treat neurodegenerative diseases. The present work is aimed to evaluate the acute toxicity of crude venom of Pelagia noctiluca and then to screen the analgesic and antibutyrylcholinestrasic (anti-BuChE) activities of the crude venom and its fractions.

Methods

Sephadex G75 gel was used to separate crude venom of Pelagia noctiluca, which led to some fractions. In addition, in vivo analgesic and in vitro plasma antibutyrylcholinestrasic activities were carried out with Pelagia crude venom and its fractions respectively.

Results

The crude venom and its fractions displayed analgesic and anti-BuChE activities at different doses without inducing acute toxicity. Fraction 2 possesses the highest analgesic and antibutyrylcholinestrasic properties. The crude venom and fraction 1 had shown to possess less significant inhibitory activity against analgesic and antibutyrylcholinestrasic models.

Conclusions

Based on this study, the crude venom of Pelagia noctiluca is found to be a useful tool for probing pharmacological activity. The purification and the determination of chemical structures of compounds of active fractions of the venom are under investigation.     

Purification and characterization of the anticoagulant principle of Trimeresurus mucrosqualatus venom

By means of CM-Sephadex column chromatography, Trimeresurus mucrosquamatus venom was separated into 20 fractions. Fraction XX had the marked anticoagulant action. This fraction was refractionated three times on Sephadex G-75, and a single peak was obtained. The patterns of microzone and disc electrophoresis also showed a single band. A single, symmetrical boundary with a value of 1.61 S was obtained by ultracentrifugation. It was a single peptide chain with a molecular weight of 11 700. The isoelectric point was higher than pH 10.The anticoagulant principle possesses phospholipase A activity and was calcium ion dependent. It did not possess proteolytic, tosyl-L-arginine methyl ester esterase, phosphodiesterase and alkaline phosphomonoesterase activities of the crude venom. The phospholipase A activity was heat-labile at pH 7.4, but was heat-stable at pH 5.6. The anticoagulant activity was more resistant to heat treatment as compared with phospholipase A activity.The anticoagulant action of the purified principle was competitively inhibited by platelet phospholipid, tissue thromboplastin and cephalin, and was neutralized by antiserum. The anticoaugulant principle inhibited platelet aggregation induced by ADP. It did not destroy fibrinogen, Factor X, prothrombin and thrombin; nor did it induce fibrinolysis nor interfere with the interaction between thrombin and fibrinogen. It is concluded that the anticoagulant action of this phospholipase A was due to the inhibition of the activations of Factors X and II through the activation of the procoagulant activity of phospholipids mediated partly by phospholipid-binding activity of this venom enzyme and partly by its enzymatic hydrolysis of phospholipids.     

Inhibition of creatine kinase activity from rat cerebral cortex by D-2-hydroxyglutaric acid in vitro

D-2-Hydroxyglutaric acid (DGA) is the biochemical hallmark of patients affected by the neurometabolic disorder known as D-2-hydroxyglutaric aciduria (DHGA). Although this disease is predominantly characterized by severe neurological findings, the underlying mechanisms of brain injury are virtually unknown. In the present study, we investigated the effect of DGA on total, cytosolic, and mitochondrial creatine kinase (CK) activities from cerebral cortex of 30-day-old Wistar rats. Total CK activity (tCK) was measured in whole cell homogenates, whereas cytosolic and mitochondrial activities were measured in the cytosolic and mitochondrial preparations from cerebral cortex. We verified that CK activities were significantly inhibited by DGA (11-34% inhibition) at concentrations as low as 0.25 mM, being the mitochondrial fraction the most affected activity. Kinetic studies revealed that the inhibitory effect of DGA was non-competitive in relation to phosphocreatine. We also observed that this inhibition was fully prevented by pre-incubation of the homogenates with reduced glutathione, suggesting that the inhibitory effect of DGA on tCK activity is possibly mediated by oxidation of essential thiol groups of the enzyme. Considering the importance of CK activity for brain metabolism homeostasis, our results suggest that inhibition of this enzyme by increased levels of DGA may be related to the neurodegeneration of patients affected by DHGA.     

Purification and properties of the anticoagulant principle of Trimeresurus gramineus venom.

By means of DEAE-Sephadex A-50 column chromatography, Trimeresurus gramineus venom was separated into 12 fractions. Fraction 8 had marked anticoagulant action in the tests of whole blood clotting time, calcium clotting time and plasma prothrombin time. Fraction 8 was rechromatographed on Sephadex G-100, then on DEAE-Sephadex A-50 again, and finally on Sephadex G-100, and a single peak was obtained. The patterns of microzone and disc electrophoresis also showed a single band. A single symmetrical boundary with 1.70 Svedberg units was obtained by ultracentrifugation. The estimated molecular weight was 19 500. The isoelectric point was pH 4.5. Chemical analysis showed that the anticoagulant principle was a glycoprotein and that it was thermolabile. The anticoagulant activity of this purified principle was 3.5 times higher than that of the crude venom. Fraction 5 potentiated its anticoagulant activity to 10 times higher than that of the crude venom. This principle did not possess caseinolytic, tosyl-L-arginine methyl ester esterase, phospholipase A, phosphodiesterase, alkaline phosphomonoesterase, fibrinolytic, hemorrhagic or local irritating activities. The purified anticoagulant principle did not destroy fibrinogen, induce fibrinolysis, inactivate thrombin nor interfere with the interaction between thrombin and fibrinogen. However, a marked inhibition of prothrombin activation was caused by the anticoagulant principle. The inhibition of prothrombin activation was not due to the destruction of prothrombin or its activation factors, but due to an interference in the interaction between prothrombin and its activation factors because of the reversible binding of these factors with the anticoagulant principle of the venom.     

Isolation and functional characterization of proinflammatory acidic phospholipase A2 from Bothrops leucurus snake venom

In the present study, an acidic PLA(2), designated Bl-PLA(2), was isolated from Bothrops leucurus snake venom through two chromatographic steps: ion-exchange on CM-Sepharose and hydrophobic chromatography on Phenyl-Sepharose. Bl-PLA(2) was homogeneous on SDS-PAGE and when submitted to 2D electrophoresis the molecular mass was 15,000Da and pI was 5.4. Its N-terminal sequence revealed a high homology with other Asp49 acidic PLA(2)s from snake venoms. Its specific activity was 159.9U/mg and the indirect hemolytic activity was also higher than that of the crude venom. Bl-PLA(2) induced low myotoxic and edema activities as compared to those of the crude venom. Moreover, the enzyme was able to induce increments in IL-12p40, TNF-α, IL-1β and IL-6 levels and no variation of IL-8 and IL-10 in human PBMC stimulated in vitro, suggesting that Bl-PLA(2) induces proinflammatory cytokine production by human mononuclear cells. Bothrops leucurus venom is still not extensively explored and knowledge of its components will contribute for a better understanding of its action mechanism.     

Fibroblast stimulation in schistosomiasis. II. Functional and biochemical characteristics of egg granuloma-derived fibroblast-stimulating factor

The pathogenetic mechanisms that underlie hepatic fibrosis in schistosomiasis are unknown, but may be under the regulation of molecules secreted by the hepatic granulomas that encase the helminth eggs. Previous studies in mice demonstrated that isolated Schistosoma mansoni egg granulomas can elaborate in vitro substances that stimulate fibroblast proliferation and collagen synthesis. The present study provides the initial characterization of the granuloma-derived factor(s). Serum-free cell culture supernatants from isolated granulomas contained activity that stimulated the uptake of (3H)-thymidine by quiescent human dermal fibroblasts. This activity was present in fractions (Sephadex G-200 chromatography) with estimated m.w. of 30,000 to 40,000. Activity eluted with linear salt gradients from ion exchange columns (DEAE Sephadex) with 0.4 to 0.7 and 1.5 to 1.8 M NaCl (pH 8.4). Activity was present in fractions with approximate pI of 6 to 6.5 and 4, prepared by flat-bed isoelectrofocusing of crude supernatant in granular gel. Activity that stimulated thymocyte proliferation in an interleukin 1 (IL 1) assay was present in crude granuloma supernatants as well as in the partially purified fractions that contained fibroblast-stimulating activity. We conclude that the granuloma-derived fibroblast-stimulating factor has biologic activity similar to IL 1 but on the basis of m.w. and pI determination is distinct from IL 1.