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PubMed2006

A novel peptide from the ACEI/BPP-CNP precursor in the venom of Crotalus durissus collilineatus.

In crotaline venoms, angiotensin-converting enzyme inhibitors [ACEIs, also known as bradykinin potentiating peptides (BPPs)], are products of a gene coding for an ACEI/BPP-C-type natriuretic peptide (CNP) precursor. In the genes from Bothrops jararaca and Gloydius blomhoffii, ACEI/BPP sequences are repeated. Sequencing of a cDNA clone from venom glands of Crotalus durissus collilineatus showed that two ACEIs/BPPs are located together at the N-terminus, but without repeats. An additional sequence for CNP was unexpectedly found at the C-terminus. Homologous genes for the ACEI/BPP-CNP precursor suggest that most crotaline venoms contain both ACEIs/BPPs and CNP. The sequence of ACEIs/BPPs is separated from the CNP sequence by a long spacer sequence. Previously, there was no evidence that this spacer actually coded any expressed peptides. Aird and Kaiser (1986, unpublished) previously isolated and sequenced a peptide of 11 residues (TPPAGPDVGPR) from Crotalus viridis viridis venom. In the present study, analysis of the cDNA clone from C. d. collilineatus revealed a nearly identical sequence in the ACEI/BPP-CNP spacer. Fractionation of the crude venom by reverse phase HPLC (C(18)), and analysis of the fractions by mass spectrometry (MS) indicated a component of 1020.5 Da. Amino acid sequencing by MS/MS confirmed that C. d. collilineatus venom contains the peptide TPPAGPDGGPR. Its high proline content and paired proline residues are typical of venom hypotensive peptides, although it lacks the usual N-terminal pyroglutamate. It has no demonstrable hypotensive activity when injected intravenously in rats; however, its occurrence in the venoms of dissimilar species suggests that its presence is not accidental. Evidence suggests that these novel toxins probably activate anaphylatoxin C3a receptors.

Amino Acid Sequence↗
PubMed2004

Peripheral neuronal nitric oxide synthase activity mediates the antinociceptive effect of Crotalus durissus terrificus snake venom, a delta- and kappa-opioid receptor agonist.

Previous work has shown that nitric oxide (NO) mediates the antinociceptive effect of Crotalus durissus terrificus venom on carrageenin-induced hyperalgesia. In the present study the role of constitutive neuronal or of inducible form of nitric oxide synthase on venom effect was determined. The rat paw prostaglandin E(2) (PGE(2))-induced mechanical hyperalgesia model was used for nociceptive evaluation. The venom (200 microg/kg) administered per oz immediately before prostaglandin induced antinociception that persisted for 120 h. The characterisation of the antinociceptive effect of the venom in this model of hyperalgesia showed that kappa and delta-opioid receptors are involved in this effect. 7-nitroindazole (7-NI), a neuronal nitric oxide synthase (NOS) inhibitor, but not L-N(6)-(1-iminoethyl)lysine (L-NIL), an inhibitor of the inducible form of NOS, injected by intraplantar (i.pl.) route, antagonized the antinociceptive effect of the venom. The i.pl. administration of 1H-(1,2,4)oxadiazolo[4,3-a]quinoxaline-1-one (ODQ), a selective guanylate cyclase inhibitor, blocked antinociception, whereas Rp-cGMP triethylamine, a cGMP-dependent protein kinase inhibitor, partially reversed this effect. These data indicate that peripheral kappa- and delta-opioid receptors are involved in the antinociceptive effect of Crotalus durissus terrificus on prostaglandin E(2)-induced hyperalgesia. Peripheral nitric oxide, generated by neuronal NO synthase, and cGMP/PKc are responsible, at least partially, for the molecular mechanisms of venom effect.

Analgesics↗
PubMed1997

An enzyme-linked immunosorbent assay (ELISA) that discriminates between the venoms of Brazilian Bothrops species and Crotalus durissus.

Enzyme-linked immunosorbent assays (ELISAs) were developed to detect specific antigens from Bothrops sp. and Crotalus durissus snake venoms in Brazil. Cross-reactive immunoglobulins from hyperimmune horse anti-Bothrops and anti-Crotalus sera were removed by immunoaffinity chromatography. Specific IgGs for Bothrops sp. and C. durissus venom antigens were prepared and used to set up a sandwich-type ELISA. The specificity of the assay was demonstrated by its capacity to identify correctly the circulating antigens in mice experimentally inoculated with both venoms. Measurable absorbance signals were obtained with 5 ng of venom per assay. The ELISA was also used to identify circulating antigens in the sera of humans bitten by Bothrops sp. and C. durissus. These ELISAs could be valuable for clinicians and epidemiologists if they prove to have both the high sensitivity and specificity required for such tests.

Animals↗
PubMed1997

Cloning and characterization of a repetitive 1.9 Kb HindIII DNA fragment from Crotalus durissus terrificus genome.

Eukaryote genomes are endowed with varying quantities of repeated DNA families. These families show different patterns of conservation among species, copy numbers, chromosomal distribution, and transcription. Characterization of repeated DNA sequences could help to understand the genome anatomy and organization or be used in molecular systematics and molecular evolution studies. We describe here a repetitive DNA sequence of the HindIII family present in the genome of the rattlesnake Crotalus durissus terrificus. In Brazil, the family Crotalus is comprised only by one species durissus, which include several subspecies. The number and distribution of these subspecies are controversial. In the present study, the genomic DNA of a female rattlesnake was digested with HindIII resulting in a strong 1.9 Kb band. A partial genomic library was constructed from the 1.9 Kb DNAs rescued from the agarose gel after HindIII digestion and ligated to the vector pGEM3Zf(+) (Promega). Analysis of 69 clones, 44 hybridized with the 1.9 Kb probe isolated from one of the clones-clone 76, indicating that the DNA isolated from this clone should represent the 1.9 Kb HindIII fragment. This 1.9 Kb HindIII DNA was completely characterized by sequencing.

Animals↗
PubMed2002

Isolation and preliminary enzymatic characterization of a novel PLA2 from Crotalus durissus collilineatus venom.

A crotoxin homolog was purified from the Crotalus durissus collilineatus venom using molecular exclusion and reverse-phase HPLC. This crotoxin contained one PLA2 (Cdcolli III F6) and four crotapotin isoforms, whereas crotoxin from Crotalus durissus terrificus venom had three PLA2 iso forms and two crotapotin isoforms. SDS-PAGE showed that the C. d. collilineatus PLA2 and crotapotin had relative molecular mass of 15 and 9 kDa, respectively. Neither the PLA2 (Cdcolli III F6) nor the crotapotins (Cdcolli III F3 and F4) had any neurotoxicity in mouse phrenic nerve-diaphragm preparations when tested alone. However, when PLA2 and crotapotin were coincubated before testing, the neurotoxicity was restored to a level similar to test in the venom in native crotoxin. The two crotapotins (Cdcolli III F3 and F4) differed in their ability to inhibit PLA2 activity, perhaps because of variations in their affinities for this enzyme. Cdcolli III F6 showed allosteric enzymatic behavior, with maximal activity at pH 8.3 and 36 degrees C. Full PLA2 activity required the presence of a low Ca2+ concentration and was inhibited by Cu2+ and Zn2+ and by Cu2+ and Mg2+ in the presence and absence of Ca2+, respectively. These results indicate that crotoxin from C. d. collineatus venom is very similar enzymatically to crotoxin from C. d. terrificus.

Amino Acid Sequence↗
PubMed2000

Interaction of the neurotoxic and nontoxic secretory phospholipases A2 with the crotoxin inhibitor from Crotalus serum.

Crotalus durissus terrificus snakes possess a protein in their blood, named crotoxin inhibitor from Crotalus serum (CICS), which protects them against crotoxin, the main toxin of their venom. CICS neutralizes the lethal potency of crotoxin and inhibits its phospholipase A2 (PLA2) activity. The aim of the present study is to investigate the specificity of CICS towards snake venom neurotoxic PLA2s (beta-neurotoxins) and nontoxic mammalian PLA2s. This investigation shows that CICS does not affect the enzymatic activity of pancreatic and nonpancreatic PLA2s, bee venom PLA2 and Elapidae beta-neurotoxins but strongly inhibits the PLA2 activity of Viperidae beta-neurotoxins. Surface plasmon resonance and PAGE studies further demonstrated that CICS makes complexes with monomeric and multimeric Viperidae beta-neurotoxins but does not interact with nontoxic PLA2s. In the case of dimeric beta-neurotoxins from Viperidae venoms (crotoxin, Mojave toxin and CbICbII), which are made by the noncovalent association of a PLA2 with a nonenzymatic subunit, CICS does not react with the noncatalytic subunit, instead it binds tightly to the PLA2 subunit and induces the dissociation of the heterocomplex. In vitro assays performed with Torpedo synaptosomes showed a protective action of CICS against Viperidae beta-neurotoxins but not against other PLA2 neurotoxins, on primary and evoked liberation of acetylcholine. In conclusion, CICS is a specific PLA2 inhibitor of the beta-neurotoxins from the Viperidae family.

Acetylcholine↗
PubMedDate not supplied

Effects of body mass, meal size, fast length, and temperature on specific dynamic action in the timber rattlesnake (Crotalus horridus).

Detailed analysis of animal energy budgets requires information on the cost of digestion (specific dynamic action [SDA]), which can represent a significant proportion of ingested energy (up to 30% in infrequent feeders). We studied the effects of snake mass, temperature (25 degrees and 30 degrees C), fasting time (1 and 5 mo), and prey size (10%-50% of snake mass) on SDA in 26 timber rattlesnakes (Crotalus horridus). We used flow-through respirometry to measure hourly CO(2) production rates (VCO2) for 1 d before and up to 17 d after feeding. Crotalus horridus, like previously studied viperids and boids, show large and ecologically relevant increases in metabolism due to feeding. Depending on treatment and individual, VCO2 increased to 2.8-11.8 times the resting metabolic rate within 12-45 h postfeeding and decreased to baseline within 4.3-15.4 d. Significant effects of snake mass, meal mass, and fast length were detected. Increased temperature decreased the time required to complete the process but had little effect on total energy expended on SDA. Energy expended on SDA increased with increasing fast length, snake mass, and prey mass. Considering all of our data, we found that a simple allometric relationship explained 96.7% of the variation in total CO(2) production during SDA. Calculations suggest that energy devoted to SDA may approach 20% of the total annual energy budget of snakes in nature. Discrepancies between our data and some previous studies draw attention to the fact that the measurement, expression, and analysis of SDA may be sensitive to several methodological and statistical assumptions.

Animals↗
PubMed1994

The origin of the diversity of crotoxin isoforms in the venom of Crotalus durissus terrificus.

Crotoxin, the main toxin from the venom of the South American rattlesnake Crotalus durissus terrificus, is a beta-neurotoxin which consists of the non-covalent association of two subunits: a phospholipase A2 subunit B (CB), and a non-enzymic subunit A (CA). We have previously purified and characterized several isoforms of each subunit of crotoxin in the venom collected from numerous snakes. Furthermore, three cDNAs encoding two CB isoforms and the precursor, pro-CA, of subunit A have been isolated from a cDNA library prepared from a single venom gland of Crotalus durissus terrificus. The aim of this study is to analyse an individual snake venom from an animal that has been used to construct a cDNA library. Several isoforms of subunit A and two isoforms of subunit B were isolated and compared to purified and characterized subunit isoforms from pooled venom. The result of this study showed that the multiplicity and the diversity of crotoxin isoforms result from post-translational modifications occurring on a precursor and from the expression of different messenger RNAs present in an individual snake. It allowed for the identification of the two CB isoforms encoding cDNAs expressed in the individual venom with two isoforms from pooled venom, CBc and probably CBa2, that belong to two classes of crotoxin complexes which can be distinguished biochemically and pharmacologically.

Amino Acid Sequence↗
PubMed2005

Acute renal failure after Crotalus durissus snakebite: a prospective survey on 100 patients.

BACKGROUND: Acute renal failure (ARF) is the main cause of death after the South American crotalid snakebite. The aim of this study was to assess the prevalence, risk factors, and characteristics of Crotalus durissus venom-induced ARF. METHODS: One hundred cases of Crotalus durissus bite were studied from hospitalization to discharge or death. Creatinine clearance (GFR) <60 mL/min/1.73 m(2) in the first 72 hours after snakebite was defined as ARF. Data are expressed as median (range of variation) or%, and were analyzed by univariate analysis and logistic regression. RESULTS: Twenty-nine patients developed ARF. Of those, 24% required dialysis and 10% died. ARF patients had smaller body surface [1.55 (0.6-2.3) vs. 1.7 (0.6-2.1) m(2), P= 0.0097], received antivenom (AV) later [12 (2-48) vs. 2 (1-14) hours, P < 0.0001], received more AV [190 (90-536) vs. 158 (75-500) mg/m(2), P < 0.0001], presented lower diuresis at admission [62 (0-182) mL/hr vs. 100 (25-325) mL/hr, P= 0.0004], and showed a striking creatine kinase (CK) increase [50,250 (69-424,120) vs. 1108 (88-133,170) U/L, P < 0.0001]. Age <12 years (OR 5.6, P= 0.026), time for AV >2 hours (OR 11.1, P= 0.032), CK at admission >2000 U/L (OR 12.7, P= 0.0009) were identified as independent risk factors for ARF, whereas diuresis at admission >90 mL/hr (OR 0.20, P= 0.014) was an independent protector factor. CONCLUSION: C. durissus venom-induced ARF had high prevalence (29%). Delay for AV treatment, CK at admission >2000 U/L, and age <12 years were independent risk factors for ARF development. Diuresis at admission >90 mL/hr was a protective factor.

Acute Kidney Injury↗
PubMed2004

Cardiovascular actions of rattlesnake bradykinin ([Val1,Thr6]bradykinin) in the anesthetized South American rattlesnake Crotalus durissus terrificus.

Incubation of heat-denatured plasma from the rattlesnake Crotalus atrox with trypsin generated a bradykinin (BK) that contained two amino acid substitutions (Arg1 --> Val and Ser6 --> Thr) compared with mammalian BK. Bolus intra-arterial injections of synthetic rattlesnake BK (0.01-10 nmol/kg) into the anesthetized rattlesnake, Crotalus durissus terrificus, produced a pronounced and concentration-dependent increase in systemic vascular conductance (Gsys). This caused a fall in systemic arterial blood pressure (Psys) and an increase in blood flow. Heart rate and stroke volume also increased. This primary response was followed by a significant rise in Psys and pronounced tachycardia (secondary response). Pretreatment with N(G)-nitro-L-arginine methyl ester reduced the NK-induced systemic vasodilatation, indicating that the effect is mediated through increased NO synthesis. The tachycardia associated with the late primary and secondary response to BK was abolished with propranolol and the systemic vasodilatation produced in the primary phase was also significantly attenuated by pretreatment, indicating that the responses are caused, at least in part, by release of cathecholamines and subsequent stimulation of beta-adrenergic receptors. In contrast, the pulmonary circulation was relatively unresponsive to BK.

Amino Acid Sequence↗
PubMed2003

Hematological, hemostatic and clinical chemistry disturbances induced by Crotalus durissus terrificus snake venom in dogs.

The aim of this study was to investigate the hematological, hemostatic and biochemical disturbances induced by the injection of Crotalus durissus terrificus venom in dogs under controlled conditions. For this purpose three groups of animals were used: an experimental group (E), which was injected i.m. with C. durissus terrificus venom (1 mg/kg); and two control groups--antivenom (AV) and control (C)--which were injected i.m. with 150 mM NaCl. Groups E and AV were treated i.v. with Crotalus antivenom 2 hours after the first injection. Serum levels of alkaline phosphatase and alanine aminotransferase were increased in groups E and AV at 24 and 48 hours after serumtherapy, respectively. The increased serum levels of myoglobin, creatine kinase and aspartate aminotransferase demonstrated that animals developed rhabdomyolysis. A persistent neutrophilic leukocytosis was already noticeable at 2 hours after envenomation and lasted even after serumtherapy. The animals of groups E and AV presented eosinopenia 24 hours after serumtherapy, and collagen-induced platelet hypoaggregation was observed without thrombocytopenia. Increased levels of fibrinogen/fibrin degradation products (FnDP/FgDP), hypofibrinogenemia, and alpha2-antiplasmin consumption were observed at 2 hours after envenomation, indicating secondary activation of fibrinolysis. Our data suggest that the biochemical and hemostatic disturbances induced by C. durissus terrificus venom in dogs are related to its myotoxic and thrombin-like activities.

Animals↗
PubMed1999

Mojave rattlesnake (Crotalus scutulatus scutulatus) identification.

Mojave rattlesnake (Crotalus scutulatus scutulatus) identification has important diagnostic and therapeutic implications. Envenomation by certain populations of Mojave rattlesnakes may cause a different clinical presentation than that caused by other rattlesnakes. Specifically, Mojave rattlesnake envenomation may cause fewer local effects and more neurologic effects (including respiratory difficulty) than are typically seen after bites from other types of rattlesnake. Thus, it is useful for clinicians to distinguish the Mojave rattlesnake from other rattlesnakes in order to prevent underestimation of severe envenomation because of the lack of local tissue injury. Patients suspected to have been bitten by Mojave rattlesnakes may need more aggressive treatment with antivenin as well as more intensive supportive care. In addition, patients suspected to have been bitten by Mojave rattlesnakes should be closely monitored for an extended observation period, as venom effects may be delayed or prolonged. Mojave rattlesnakes may be particularly difficult to distinguish from Western Diamondback rattlesnakes (Crotalus atrox) because of their similarity in appearance and overlapping ranges. The purpose of this report is to provide clinicians with key characteristics which may assist in distinguishing Mojave rattlesnakes from Western Diamondback and other rattlesnakes.

Animals↗
PubMed2002

Geographic and ontogenic variability in the venom of the neotropical rattlesnake Crotalus durissus: pathophysiological and therapeutic implications.

A comparative study was performed on the venoms of adult specimens of the neotropical rattlesnake, Crotalus durissus, from Guatemala, Costa Rica, Venezuela and Brazil, together with the venom of newborn specimens of C. d. durissus from Costa Rica. Venoms from Brazil (C. d. terrificus) and from newborn specimens of C. d. durissus presented an electrophoretic pattern characterized by the predominance of bands with molecular mass of 36 and 15 kDa, whereas those of adult specimens of C. d. durissus from Guatemala and Costa Rica, and C. d. cumanensis from Venezuela, showed a conspicuous band of 62 kDa, and additional bands of 36, 29 and 15 kDa. Moreover, venoms from C. d. terrificus and C. d. cumanensis showed a prominent band of < 10 kDa that probably corresponds to crotamine, since a 'crotamine-like' activity was detected in these venoms upon intraperitoneal injection in mice. Venoms of C. d. terrificus, C. d cumanensis and newborn C. d. durissus induced higher lethal and myotoxic effects than those of adult C. d. durissus. In contrast, adult C. d. durissus and C. d. cumanensis venoms induced hemorrhage, whereas venoms of C. d. terrificus and newborn C. d. durissus lacked this effect. All venoms showed coagulant effect in plasma, the highest activity being observed in the venom of newborn C. d. durissus. An anti-crotalic antivenom produced by Instituto Butantan (Brazil), using C. d. terrificus venom as antigen, was effective in the neutralization of lethal, myotoxic and coagulant effects of all venoms studied, being ineffective in the neutralization of hemorrhagic activity of the venoms of C. d. cumanensis and C. d. durissus. On the other hand, a polyvalent antivenom produced by Instituto Clodomiro Picado (Costa Rica), using the venoms of C. d. durissus. Bothrops asper and Lachesis stenophrys as antigens, was able to neutralize lethal, myotoxic, coagulant and hemorrhagic effects of C. d. durissus venom, but was ineffective in the neutralization of lethality and myotoxicity of C. d. terrificus, C. d. cumanensis and newborn C. d. durissus venom. The high toxicity of South American and newborn C. d. durissus venoms is related to the presence of high concentrations of the neurotoxic phospholipase A2 complex 'crotoxin'. Accordingly, antivenom from Instituto Butantan has a much higher titer of anti-crotoxin antibodies than antivenom from Instituto Clodomiro Picado. Crotalus durissus represents an example of intraspecies variation in venom composition and pharmacology that has relevant pathophysiologic and therapeutic implications.

Animals↗
PubMed1994

A phospholipase A2 inhibitor from the plasma of the South American rattlesnake (Crotalus durissus terrificus). Protein structure, genomic structure, and mechanism of action.

The lethal toxicity of the South American rattlesnake (Crotalus durissus terrificus) venom can be attributed mainly to the presence of a pre-synaptic neurotoxin, crotoxin, with phospholipase A2 activity. Crotoxin is a heterodimer of an acidic protein (CA) and a basic phospholipase A2 (CB). An anti-toxic protein of subunit molecular mass 23.6 kDa that neutralizes both lethal and PLA2 activity of crotalid venom and crotoxin has been previously purified from the plasma of this snake (Fortes-Dias, C., Fonseca, B. C. B., Kochva, E., and Diniz, C. R. (1991) Toxicon 29, 997-1008). The protein has been named CNF for Crotalus neutralizing factor. In the present study, we have shown that CNF exists as an oligomeric aggregate of (CNF)n, where n = 6-8, and when it interacts with crotoxin, it replaces the acidic protein CA of crotoxin to form a stable near stoichiometric complex of CNF.CB. The CNF.CB complex no longer exhibits PLA2 activity and is inert in vivo. Thus, the exchange reaction between CA.CB of crotoxin and CNF to form CNF.CB and free CA is reminiscent of the interaction of crotoxin with its target receptor at the neuromuscular transmission site in the presynaptic cells. A cDNA encoding CNF has been isolated from a liver cDNA library using an appropriate nucleotide probe. The nucleotide sequence codes for a 19-residue signal peptide, followed by a 181-residue protein of which 16 are half-cystines. Calculated molecular mass is 20.06 kDa, and there is a putative N-linked carbohydrate site at Asn157.

Amino Acid Sequence↗
PubMed1993

Experimental transmission of Caryospora bigenetica Wacha et Christiansen, 1982 (Apicomplexa: Eimeriidae) from a rattlesnake, Crotalus atrox, to rodents and pigs.

Caryosporan oocysts were found in the feces of a diamond rattlesnake, Crotalus atrox, kept in ZOO Ustí nad Labem, Czech Republic. Comparison of oocyst structure with hitherto described Caryospora species from snakes revealed that they were Caryospora bigenetica Wacha et Christiansen, 1982. The rattlesnake, Crotalus atrox, represents a new host for C. bigenetica. The common vole (Microtus arvalis) and gerbil (Meriones unguiculatus) were successfully infected with a mixture of C. bigenetica oocysts and sporocysts following oral inoculation. All experimentally infected animals displayed clinical signs of dermal coccidiosis, including swellings of the face, ears, footpads, and scrota or vagina. Gerbils developed more severe clinical signs of infection and had a higher mortality than voles. Developmental stages of C. bigenetica were found in connective tissue of the nose, cheeks, ears, scrotum or vagina. Transmission of C. bigenetica caryocysts between common voles and mice, between mice and common voles, common voles and gerbils, and common voles and pigs was demonstrated. This study demonstrates that C. bigenetica can be transmitted by predation or cannibalism between different species of rodents and pigs.

Animals↗
PubMed1981

Tectal projections of an infrared sensitive snake, Crotalus viridis.

Crotaline snakes have detectors for infrared radiation and this information is projected to the optic tectum in a spatiotopic manner. The tectal projections were examined in Crotalus viridis with the use of silver methods for degenerating fibers and the autoradiographic and horseradish peroxidase tracing methods. Large lesions included all of the tectal layers but not the underlying structures. Projections to the thalamus include a sparse input to the ipsilateral ventral and dorsal lateral geniculate nuclei, the ventromedial nucleus, and nucleus lentiformis thalami. Nucleus rotundus was not detected. The projections to the pretectal nuclei are primarily ipsilateral to the nucleus lentiformis mesencephali and pretectal nucleus. At the level of the mesencephalon, tectal efferents are bilateral to nucleus profundus mesencephali and the tegmentum. There is minimal input to the contralateral deep tectal layers. There are ipsilateral terminations in a nucleus identified as the posterolateral tegmental nucleus. Descending fibers include the two major tracts--the ventral tectobulbar tract that terminates in the ipsilateral lateral reticular formation and the predorsal bundle that distributes throughout the contralateral medial reticular formation. Two small descending tracts were noted--the intermediate and dorsal tectobulbar tracts. All of these descending tracts appear to terminate by the time they reach the caudal medulla. After superficial lesions terminals could be found in the ventral lateral geniculate nucleus, the nucleus profundus mesencephali, and the posterolateral tegmental nucleus; the two major descending tracts contained degenerated fibers as well. The areas receiving tectal input in Crotalus were compared to those of other reptiles and discussed.

Animals↗
PubMed1995

Nucleotide sequence encoding the snake venom fibrinolytic enzyme atroxase obtained from a Crotalus atrox venom gland cDNA library.

Atroxase, isolated from the venom of Crotalus atrox (western diamondback rattlesnake), is a nonhemorrhagic protease which has fibrinolytic activity in vivo. The primary structure of atroxase was deduced from the cDNA encoding the atroxase protein. The venom glands of Crotalus atrox were used to prepare a cDNA library. Degenerate oligonucleotides were synthesized based on the partial amino acid sequence of atroxase and were used as primers in the polymerase chain reaction to amplify overlapping cDNA fragments from the C. atrox cDNA library. The resulting cDNA fragments were subcloned, sequenced, and translated. The final nucleotide sequence shows high homology to previously described primary structures of nonhemorrhagic fibrinolytic proteases isolated from snake venom.

Amino Acid Sequence↗
PubMed1997

Crovidisin, a collagen-binding protein isolated from snake venom of Crotalus viridis, prevents platelet-collagen interaction.

By means of liquid chromatography consisting of gel filtration, anionic exchange, and C8 reverse-phase HPLC, a selective inhibitor of collagen-induced platelet aggregation, named crovidisin, has been purified to homogeneity from the venom of Crotalus viridis snake. Crovidisin is a single-chain, 53-kDa protein with a selective inhibitory activity on collagen-induced aggregation of human washed platelets without affecting those elicited by thrombin, sodium arachidonate, and ADP. Partial sequencing of tryptic digests of crovidisin reveals that partial sequence of crovidisin appears to be identical to that of catrocollastatin, a collagen antagonist occurring in the venom of Crotalus atrox snake. Crovidisin dose-dependently blocked aggregation of human washed platelets triggered by 5 and 10 microg/ml of collagen with IC50 of 0.17 and 0.47 microM, respectively. Not only platelet aggregation but also release reaction, thromboxane formation, and increase of intracellular Ca2+ level of platelets in response to collagen were all completely abolished by crovidisin. In the presence of crovidisin, the Mg2+-dependent adhesion of platelets to collagen was diminished in a dose-dependent manner, while the glycoprotein IIb/IIIa-mediated platelet-fibrinogen interaction was unaffected. When collagen was pretreated with crovidisin and followed by three washes with phosphate-buffered saline, the antiadhesion activity of crovidisin was unaffected. In addition, collagen fibers emitted fluorescence after incubation with fluorescein isothiocyanate-conjugated crovidisin, indicating that crovidisin binds directly to collagen fibers. In conclusion, crovidisin blocks the interaction between platelets and collagen fibers through its binding to collagen fibers, resulting in the blockade of collagen-mediated platelet functions such as adhesion, release reaction, thromboxane formation, and aggregation.

Adult↗