Publications

a comparison of the crystal structures of phospholipase a2 from bovine pancreas and crotalus atrox venom.	the refined high resolution crystal structure of the bovine phospholipase a2 was compared with its counterpart from the venom of crotalus atrox, the western diamondbacked rattlesnake. the strong similarity in their backbone conformations forms the basis of a common numbering system for the amino acid sequence. the three common major helices and much of the extended chain form a nearly identical "homologous core" structure. the variations in conformation usually arise from deletions/insertions or ...	1985	4044572
conservation of human fibrinogen conformation after cleavage of the b beta chain nh2 terminus.	human fibrinogen exposed to protease iii from crotalus atrox venom is cleaved near the nh2 terminus of the b beta chain yielding a species of mr 325,000 (fg325) with impaired thrombin clottability. the derivative was compared with intact fibrinogen in a number of ways to determine whether the functional defect resulted from a conformational change or from the loss of a polymerization site. nh2-terminal amino acid sequencing of isolated a alpha, b beta, and gamma chains showed that fg325 containe ...	1985	2579073
[nle4, d-phe7]-alpha-msh: a superpotent melanotropin with prolonged action on vertebrate chromatophores.	the in vitro and in vivo responses of integumental chromatophores to alpha-msh and a related analogue, [nle4, d-phe7] -alpha-msh, were studied in a number of vertebrate species: the teleost, lebistes reticulatus; the amphibians, rana pipiens, r. catesbeiana, xenopus laevis, bufo alvarius, and b. cognatus; the lizard, anolis carolinensis; the rattlesnake, crotalus atrox. the alpha-melanotropin analogue was a superpotent agonist in the in vitro frog (r. pipiens, r. catesbeiana) and lizard (a. caro ...	1985	2859941
proteolytic specificity of hemorrhagic toxin b from crotalus atrox (western diamondback rattlesnake) venom.	in our effort to identify the proteolytic specificity of various hemorrhagic toxins isolated from western diamondback rattlesnake venom, hemorrhagic toxin b was isolated in homogeneous form by previously published methods. hemorrhagic toxin b hydrolyzed glucagon, producing six fragments. the proteolytic sites were identified as thr(5)-phe(6), thr(10)-ser(11), asp(15)-ser(16), asp(21)-phe(22) and try(25)-leu(26). when oxidized insulin b chain was used, proteolysis occurred at four sites: asn(3)-g ...	1985	2865065
separation of crotalus atrox (western diamondback rattlesnake) alpha-proteinase from serine proteinase and hemorrhagic factor activities.	a method for obtaining crotalus atrox alpha-proteinase (ec 3.4.24.1) in a pure form has been developed. fractionation of the crude venom on deae-sepharose, followed by gel filtration on bio-gel p-150 and chromatography on cm-sepharose, yielded an alpha-proteinase preparation which showed a single band on disc and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and had an activity on casein approximately twice that previously reported. the enzyme is a nonglycosylated single-chain polype ...	1985	3913334
isolation and characterization of hemorrhagic toxin g from the venom of crotalus atrox (western diamondback rattlesnake).	hemorrhagic toxin g (ht-g) was isolated from crotalus atrox (western diamondback rattlesnake) venom using a five-step purification procedure to obtain approximately equal to 5.9 mg of purified ht-g from 2.0 g of crude venom. the purified toxin was homogeneous by disc electrophoresis on polyacrylamide gel at ph 8.3 and 4.3, and by isoelectric focusing. ht-g possessed lethal, hemorrhagic and proteolytic activities. these activities of toxin were inhibited by ethylenediamine-tetraacetic acid (edta) ...	1985	3834802
the refined crystal structure of dimeric phospholipase a2 at 2.5 a. access to a shielded catalytic center.	the 2.5-a crystal structure of the calcium-free form of the dimeric venom phospholipase a2 from the western diamondback rattlesnake crotalus atrox, has been refined to an r-factor of 17.8% (i greater than 2 sigma) and acceptable stereochemistry. the molecule is a nearly perfect 2-fold symmetric dimer in which most of the catalytic residues of both subunits face an internal cavity. the restricted access to the putative catalytic sites is especially puzzling as the optimal substrates for this and ...	1985	4019493
rattlesnake bite of glans penis.	the envenomation of the glans penis by a western diamondback rattlesnake (crotalus atrox) is presented. effects of envenomation, first aid, and hospital management are briefly reviewed.	1985	4012978
specificity of hemorrhagic proteinase from crotalus atrox (western diamondback rattlesnake) venom.	hemorrhagic proteinase, htb, isolated from crotalus atrox (western diamondback rattlesnake) venom was studied for its specificity. htb showed fibrinogenase activity, hydrolyzing the a alpha chain of fibrinogen first, followed by the cleavage of the b beta chain. htb is different from thrombin and did not produce a fibrin clot. the degradation products of fibrinogen were found to be different, indicating that the cleavage sites in the a alpha and b beta chains are different from those of thrombin ...	1985	3888273
a new peptide from crotalus atrox snake venom.	the presence of new hypotensive peptides, possibly not related to ace inhibition, has been investigated on 66 snake venoms from crotalid, viperid and elapid families. only the venom of crotalus atrox showed a substantial amount of a new decapeptide, called pol-236, with the following aminoacid sequence: pyr-leu-trp-pro-arg-pro-gln-ile-pro-pro. pharmacological assays performed on the synthesized peptide revealed effects on blood pressure, probably derived from vascular and cardiac interferences.	1985	3831966
self-association and active enzyme forms of naja naja naja and crotalus atrox phospholipase a2 studied by analytical ultracentrifugation.	the dimerization of phospholipase a2 (plpa2) from naja naja naja (pakistani cobra) and crotalus atrox (western diamondback rattlesnake) has been studied from ph 2.5 to 11 at 20 degrees c in 1 mm cacl2, 0.21 m ionic strength. for the c. atrox enzyme, it was found necessary to use a combination of sedimentation equilibrium and fluorescence yield data to analyze the association. sedimentation equilibrium in the analytical ultracentrifuge sufficed for the study of the n. naja plpa2. in the region of ...	1986	3801457
identification of the tryptophan residue located in the calcium binding site of trimeresurus flavoviridis phospholipase a2.	when phospholipase a2 from the venom of trimeresurus flavoviridis (the habu snake) was oxidized with n-bromosuccinimide at ph 4.0, its activity decreased linearly with increase in the extent of oxidation of tryptophan residues. oxidation of two of the four tryptophan residues caused an apparent loss of activity. the accessibilities of the tryptophan residues were analyzed with differently oxidized phospholipase a2 preparations and were determined to be in the following order: trp-3 approximately ...	1986	3818568
ability of polyvalent (crotalidae) antivenom to neutralize local myonecrosis induced by crotalus atrox venom.	wyeth's polyvalent (crotalidae) antivenom was tested in mice for its ability to neutralize local myonecrosis induced by crude crotalus atrox venom. a light microscopic assay was used to quantitate myonecrosis after i.m. injection of antivenom-venom mixtures. the results indicate that antivenom neutralizes the local myotoxicity of up to 15 micrograms venom per g body weight of mice. this neutralization is significantly better than that previously reported for crotalus viridis viridis venom.	1986	3705097
fatal rattlesnake envenomation in arizona: 1969-1984.	case histories of the last nine fatalities (1969-1984), in which the cause of death on the state of arizona certificate of death was snakebite, were reviewed. six males and three females ranged in age from 2 to 77 years, and were bitten between 0800-2100 hours from april to september. bites in three adult males were "illegitimate" and of these, two were by captive mojave rattlesnakes, crotalus s. scutulatus. the latter two victims had been bitten previously and remained at home, refusing treatme ...	1986	3701904
cross-reactivity and neutralization by rabbit antisera raised against crotoxin, its subunits and two related toxins.	antisera were raised against intact crotoxin (crotalus durissus terrificus), mojave toxin (crotalus scutulatus scutulatus) and concolor toxin (crotalus viridis concolor), as well as the subunits of crotoxin. double immunodiffusion and enzyme-linked immunosorbent assays (elisa) demonstrated antigenic similarity between these three purified toxins and their subunits. additionally, when crotoxin antisera were pre-incubated with each of the three toxins before injection, the lethal activity of all w ...	1986	3095955
geographic and ontogenic variation in venom of the western diamondback rattlesnake (crotalus atrox).	venom samples from western diamondback rattlesnakes (crotalus atrox) from 13 localities in the united states were tested for i.v. and s.c. lethality for mice, protease activity, hemorrhagic activity, and the presence of mojave toxin. electrophoresis on polyacrylamide gel was used to compare protein composition. the neutralizing effect of two commercial antivenoms was evaluated against selected samples of venom. venom of young snakes from north texas was compared with that of adults from the same ...	1986	3513378
substrate specificities and inhibition of two hemorrhagic zinc proteases ht-c and ht-d from crotalus atrox venom.	the proteolytic specificities of two zinc hemorrhagic toxins (ht-c and ht-d), isolated from crotalus atrox venom, were investigated by using the oxidized b chain of bovine insulin and synthetic peptide substrates. the enzymes cleaved the ala14-leu15 bond of the insulin b chain most rapidly and the tyr16-leu17 slightly more slowly. the his5-leu6, his10-leu11, and gly23-phe24 bonds were also cleaved but at considerably slower rates. in order to assess the substrate length preferences of the enzyme ...	1986	3514216
amino acid sequence of trimeresurus flavoviridis phospholipase a2.	the amino acid sequence of phospholipase a2 from the venom of trimeresurus flavoviridis (the habu snake) was determined. the enzyme subunit has a molecular weight of 13,764 and consists of a single polypeptide chain of 122 amino acids and seven disulfide bonds. the fragmentation was conducted by digesting the reduced and s-carboxymethylated derivative of the protein with achromobacter protease i, chymotrypsin, and trypsin, respectively. achromobacter protease i peptides were used for alignment a ...	1986	3514593
helodermatine, a kallikrein-like, hypotensive enzyme from the venom of heloderma horridum horridum (mexican beaded lizard).	we have purified and characterized the major n-benzoyl-l-arginine ethyl ester hydrolase from the venom of heloderma horridum horridum. the enzyme belongs to the serine proteinase family, and its activity vs. peptide amide substrates and human high-molecular-weight kininogen suggests a similarity to the family of kallikreins. this interpretation is corroborated by its reactivity with the natural inhibitors soybean trypsin inhibitor and kunitz-type bovine pancreatic trypsin inhibitor (aprotinin). ...	1986	3537191
synthetic peptides related to the n-terminal amino acid sequence of a pharmacologically active decapeptide isolated from crotalus atrox snake venom.	synthesis is described of some peptides and peptide derivatives related to the n-terminal amino acid sequence of a pharmacologically active decapeptide (pol-236) recently isolated from crotalus atrox snake venom. the synthetic compounds were tested for hypotensive activity in anaesthetized normotensive rats. at the used doses all compounds failed to show the immediate hypotensive effect noted after pol-236 administration.	1986	3743744
an isoelectric focusing study of seasonal variation in rattlesnake venom proteins.	adult specimens of seven southern pacific rattlesnakes (crotalus viridis helleri), four northern black-tailed rattlesnakes (crotalus molossus molossus), and six western diamondback rattlesnakes (crotalus atrox) were housed under controlled light and temperature and milked of venom monthly for 20 months. ambient conditions were modelled to simulate seasonal change. weighed amounts of lyophilized venom from each snake were compared chronologically for variation in isoelectric focusing patterns, us ...	1986	3824406
a complete amino acid sequence for the basic subunit of crotoxin.	the complete amino acid sequence of the basic subunit of crotoxin from the venom of crotalus durissus terrificus has been determined. fragmentation of the protein was achieved by using cyanogen bromide and arginine- and lysine-specific endoproteases. sixteen glx and asx residues reported by fraenkel-conrat et al. (1980) in natural toxins (d. eaker and t. wadstrom, eds.), pp. 561-567, pergamon, oxford.) have been resolved as glu or gln and asp or asn residues, respectively. most of the remaining ...	1986	3753003
nephrotoxic action of rattlesnake and sea snake venoms: an electron-microscopic study.	the fine structure of renal corpuscles and proximal convoluted tubules of the right kidneys of suiss mice were studied 9 hr after the injection of the venom of crotalus atrox (western diamond-back rattlesnake) or the venom of laticauda semifasciata (broad-banded blue sea snake). rattlesnake envenomation resulted in several ultrastructural changes in the renal corpuscles and proximal convoluted tubules. visceral epithelial changes included intracellular oedema, blebbing, vesiculations, the format ...	1987	1255307
hydrolysis of 1-palmitoyl-2-[6-(pyren-1-yl)]hexanoyl-sn-glycero- 3-phospholipids by phospholipase a2: effect of the polar head-group.	the effect of the phospholipid polar head-group on the porcine pancreatic phospholipase a2 (phosphatidylcholine 2-acylhydrolase, ec 3.1.1.4) reaction was studied using 1-palmitoyl-2-[6-(pyren-1-yl)]hexanoyl-sn-glycero-3- phosphatidylcholine, -ethanolamine, -glycerol, -monomethylester and -serine as substrates. except for the monomethylester analogue, which was maximally activated by 3.5 mm cacl2, maximal enhancement of hydrolysis of the other pyrenephospholipids was obtained at 2 mm ca2+. sodium ...	1987	3801511
dissociation of 5-fluorouracil-induced dna fragmentation from either its incorporation into dna or its cytotoxicity in murine t-lymphoma (s-49) cells.	we have shown previously (w. b. parker and p. klubes, cancer res., 45:4249-4256, 1985) that uridine (10 microm) enhanced the cytotoxicity of 5-fluorouracil (fura) in cultured mouse t-lymphoma (s-49) cells. here we show, by the use of colony formation assays, that approximately 50% of the cytotoxicity of fura plus uridine could be prevented by the simultaneous administration of thymidine (2.5 to 10 microm). in order to explain our observation of a thymidine-preventable component of the cytotoxici ...	1987	3802103
monoclonal antibodies against an intracellular phospholipase a2 from rat liver and their cross-reactivity with other phospholipases a2.	the membrane-associated phospholipase a2 from rat liver mitochondria was solubilized and partially purified by aca 54 gel filtration and matrex gel blue a chromatography. the approximately 2500-fold purified preparation was injected into mice to prepare monoclonal antibodies against phospholipase a2 after fusion of spleen cells and mouse sp2/0 myeloma cells. hybridoma supernatants were assayed for antibody production in enzyme-linked immunosorbent assay with partially purified phospholipase a2 a ...	1987	3830178
life-threatening airway obstruction from rattlesnake bite to the tongue.	we describe the case of a 41-year-old man who suffered a bite to the tongue from the western diamondback rattlesnake (c atrox). life-threatening obstruction of his upper airway secondary to massive edema of the tongue and other soft tissue structures quickly followed envenomation. nasotracheal intubation, iv antivenin, and supportive care resulted in complete recovery with no permanent deficits. rattlesnake bites to the tongue are rare and pose an unusual cause of airway obstruction.	1987	3592340
bacillus cereus phospholipase c: carboxylic acid ester specificity and stereoselectivity.	thiophosphate analogs of phosphatidylcholine have been synthesized with varying structural complexity. these analogs have been used in a continuous spectrophotometric assay for phospholipase c (bacillus cereus) to estimate the minimal structural requirements associated with the non-polar portion of the substrate phospholipid. the analogs were of three types containing zero, one or two carboxylic acid ester functionalities. the analogs with one or two ester groups acted as substrates for phosphol ...	1987	3111540
solubilization of calcium channel antagonist binding sites from rat brain.	calcium antagonist binding sites were solubilized from rat brain membranes using the detergent 3-[(3-cholamidopropyl)dimethylammonio] 1-propanesulfonate (chaps). chaps-solubilized [3h]nitrendipine binding sites are saturable over a range of 0.05-4 nm and scatchard analysis reveals a single, high-affinity (kd = 0.49 +/- 0.10 nm), low-capacity (bmax = 56 +/- 4 fmol/mg of protein) binding site. reversible ligand competition experiments using solubilized binding sites demonstrated appropriate pharma ...	1987	2440991
the stereoselectivity of the clostridium perfringens phospholipase c: hydrolysis of thiophosphate analogs of phosphatidylcholine.	thiophosphate containing analogs of phosphatidylcholine have been synthesized with varying degrees of structural complexity. these analogs have been used in a continuous spectrophotometric assay for phospholipase c from clostridium perfringens in order to examine the requirement for substrate ester functionalities and the stereoselectivity of the enzyme. the substrate analogs with ester groups in the nonpolar portion of the molecule were acceptable substrates for phospholipase c, while those ana ...	1987	2890329
immunofluorescent localization of the ca2+-dependent proteinase and its inhibitor in tissues of crotalus atrox.	the native 108,000 dalton ca2+-dependent proteinase (cdp) and its 115,000 dalton protein inhibitor (cdpi) were purified from bovine skeletal muscle using native polyacrylamide gel electrophoresis and were used to elicit antibody production in rabbits and balb/c mice. polyclonal antibodies were purified as igg fractions by column chromatography; monoclonal antibodies were produced by the hybridoma technique. indirect immunofluorescence localization of cdp and cdpi in tissues of crotalus atrox sho ...	1987	3035058
characterization of two hemorrhagic zinc proteinases, toxin c and toxin d, from western diamondback rattlesnake (crotalus atrox) venom.	two hemorrhagic proteinases from crotalus atrox venom, hemorrhagic toxin c (ht-c) and hemorrhagic toxin d (ht-d), were characterized and compared to one another. the two toxins are zinc metalloproteinases which both have molecular weights of 24,000. their isoelectric points are slightly acidic, ht-c being the more basic of the two with an isoelectric point of 6.2, whereas ht-d has an isoelectric point of 6.1. only minor differences were found in the amino acid compositions of the two toxins. the ...	1987	3101740
studies on the mechanism of hemorrhage production by five proteolytic hemorrhagic toxins from crotalus atrox venom.	the sites and relative rates of peptide bond hydrolysis of the oxidized b chain of bovine insulin by two hemorrhagic proteinases, ht-a and ht-b, isolated from the venom of the western diamondback rattlesnake, crotalus atrox, were investigated. the results were compared with previous results on the digestion of the same substrate by the c. atrox hemorrhagic proteinases ht-c, d, and e. both toxins, ht-a and ht-b, were found to cleave the his5-leu6, his10-leu11, ala14-leu15, and tyr16-leu17 bonds o ...	1988	3060135
efficacy of delayed administration of crotalid antivenom and crystalloid fluids.	clinical and research reports suggest that the efficacy of antivenom declines when its administration is delayed after envenomation. a controlled sequential trial was performed comparing the efficacy of three treatments to untreated controls when applied 1 hr after subcutaneous injection of rats with crotalus atrox venom. survival was decreased in all groups when treatment was delayed for 1 hr. survival was highest in animals treated with both antivenom and saline, followed by antivenom alone, s ...	1988	3238705
the chemical basis for interfacial activation of monomeric phospholipases a2. autocatalytic derivatization of the enzyme by acyl transfer from substrate.	a basic monomeric phospholipase a2 from the venom of the american water moccasin, agkistrodon piscivorus piscivorus, undergoes ca2+-dependent, autocatalytic acylation during the course of hydrolysis of both model and natural phospholipid substrates. acylation occurs at 2 lysine residues, lys-7 and lys-10, in the nh2-terminal alpha-helical segment of the enzyme, and when both positions are fully derivatized, the stable bisacylphospholipase a2 becomes a dimer in solution. the acylated enzyme is fu ...	1988	3403524
preparation of a crotoxin neutralizing monoclonal antibody.	crotoxin is a heterodimeric protein composed of an acidic and basic subunit from the venom of crotalus durissus terrificus and is representative of a number of presynaptically acting neurotoxins found in the venom of rattlesnakes. four different monoclonal antibodies, typed as igg1 subclass, were raised against the basic subunit of this toxin. one was a potent neutralizing antibody of intact crotoxin, which could neutralize approximately 1.6 moles of purified crotoxin per mole of antibody. the m ...	1988	3201488
purification and biochemical characterization of atroxase, a nonhemorrhagic fibrinolytic protease from western diamondback rattlesnake venom.	crotalus atrox venom contains a variety of proteases which render fibrinogen incoagulable and solubilize fibrin. one of these proteases was purified by using ion-exchange and gel permeation liquid chromatography. the protease, called atroxase, consists of a single nonglycosylated polypeptide chain with a molecular weight of 23,500 and an isoelectric point of ph 9.6. amino acid analysis indicates atroxase to contain 206 residues with no sulfhydryl groups. metal analysis found zinc and potassium a ...	1988	3167016
proton nmr resonance assignments and surface accessibility of tryptophan residues of a dimeric phospholipase a2 from trimeresurus flavoviridis.	proton nmr spectra of a dimeric phospholipase a2 from trimeresurus flavoviridis have been recorded. n-1 proton resonances of the tryptophan indole rings have been detected and assigned to specific positions, trp-3/trp-30, trp-68 and trp-108, by comparing the spectra of the enzyme derivatives with tryptophans oxidized to differing extents. photo-cidnp experiments have revealed that trp-68 and trp-108 are exposed while trp-3 and trp-30 are buried in the molecule. this is consistent with the x-ray ...	1988	3350151
classification of myonecrosis induced by snake venoms: venoms from the prairie rattlesnake (crotalus viridis viridis), western diamondback rattlesnake (crotalus atrox) and the indian cobra (naja naja naja).	the pathogenesis of myonecrosis induced by three different snake venoms was studied by light microscopic examination of skeletal muscle tissue taken at time periods ranging from 0.25 hr to 4 weeks after an intramuscular injection of the venom into mice. it was possible to identify different types of myonecrosis based on the abnormal morphologic states of the damaged cells. the types of myonecrosis observed correlated with the types of components present in the venom injected. venoms containing d ...	1988	3188052
investigation of an active site histidine-aspartate couple in trimeresurus flavoviridis phospholipase a2.	when trimeresurus flavoviridis phospholipase a2 was reacted with methyl p-nitrobenzenesulfonate, its activity decreased following first-order kinetics. the ph dependence of the rate constants of inactivation showed that his-48 with an apparent pka of 6.5 controls the reaction. in the ph region below 6.5, n1-methylhistidine was predominantly formed. on the other hand, n1,n3-dimethylhistidine was almost exclusively produced in the ph region above 6.5. no n3-methylhistidine was detected at any ph t ...	1989	2628422
degradation of extracellular matrix proteins by hemorrhagic metalloproteinases.	the proteolytic activity of four hemorrhagic metalloproteinases (ht-a, c, d, and e) isolated from the venom of the western diamondback rattlesnake (crotalus atrox) was investigated using isolated extracellular matrix (ecm) proteins. we determined that all of the proteinases are capable of cleaving fibronectin, laminin, type iv collagen, nidogen (entactin), and gelatins. however, none of the proteinases were proteolytic against the interstitial collagen types i and iii or type v collagen. with al ...	1989	2817904
comparative enzymatic study of hplc-fractionated crotalus venoms.	1. ten venoms of the genus crotalus (crotalus adamanteus, crotalus atrox, crotalus durissus durissus, crotalus horridus horridus, crotalus lepidus, crotalus polystictus, crotalus molossus molossus, crotalus pusillus, crotalus scutulatus scutulatus, venom b, and crotalus viridis lutosus) were fractionated using hplc anion and cation exchange chromatography. 2. hplc venom fractions were tested for hemorrhagic, hemolytic, and proteolytic activities. 3. crude virginia opossum (didelphis virginiana) ...	1989	2680253
responses by canids to scent gland secretions of the western diamondback rattlesnake (crotalus atrox).	many snakes discharge malodorous fluids from paired scent glands in the base of the tail when they are disturbed. a number of authors suggest that these secretions repel predators. scent gland secretions of the western diamondback rattlesnake (crotalus atrox), or dichloromethane extracts of them, were presented to coyotes (canis latrans) in three field tests, and to domestic dogs (canis familiaris) in two kennel tests, to determine whether responses of possible benefit to snakes are elicited. fr ...	1989	24272101
catroxobin, a weakly thrombin-like enzyme from the venom of crotalus atrox. nh2-terminal and active site amino acid sequences.	two thrombin-like isoenzymes, termed catroxobins, were purified by gel filtration and ion exchange chromatography to electrophoretic homogeneity from the venom of the western diamondback rattlesnake, crotalus atrox. by sds-polyacrylamide gel electrophoresis their molecular weights were estimated to be 25,000 and 26,200. a 43-residue nh2-terminal sequence, containing the active histidine residue, was the same for the two isoenzymes. in addition, a 33-residue internal peptide from catroxobin i con ...	1989	2617466
thrombolysis with a snake venom protease in a rat model of venous thrombosis.	a fibrin(ogen)olytic protease isolated from the venom of crotalus atrox (the western diamondback rattlesnake) was tested for thrombolytic activity. the protease, called atroxase, solubilized fibrin when tested on fibrin plates and hydrolyzed fibrinogen rendering it incoagulable with a specific fibrinogenolytic activity of 42 mg fibrinogen/min/mg protein. atroxase was unable to activate plasminogen. in vivo, fibrinolytic activity was tested on artificial thrombi induced in the posterior vena cava ...	1989	2646751
antigenic relationships of fractionated western diamondback rattlesnake (crotalus atrox) hemorrhagic toxins and other rattlesnake venoms as indicated by monoclonal antibodies.	seven hemorrhagic factors have been isolated from crotalus atrox venom, but their antigenic relationships have not been well studied. in this study, two different monoclonal antibodies, c. atrox peak 8 (ca-p-8) and c. atrox subclone 5 (ca-5+), were produced against two c. atrox venom hemorrhagic fractions and used in an elisa (enzyme-linked immunosorbent assay) to determine if the hemorrhagic factors in c. atrox venom are antigenically related. the same elisa test was used to determine cross-rea ...	1989	2718192
amino acid sequence of a crotalus atrox venom metalloproteinase which cleaves type iv collagen and gelatin.	the hemorrhagic toxin ht-d from venom of the western diamondback rattlesnake is a metalloproteinase with a molecular weight of 23,234. peptides were obtained from enzymatic and chemical digestions, separated by reverse-phase chromatography, and sequenced in a gas-phase sequenator. the sequence showed a putative zinc binding site similar to that of thermolysin and other metalloproteinases but no overall significant similarity to the sequences of other metalloproteinases and may represent a new su ...	1989	2745407
preliminary observations on the effects of hyperbaric oxygen therapy on western diamondback rattlesnake (crotalus atrox) venom poisoning in the rabbit model.	intermittent hyperbaric oxygen therapy has been shown to reduce skeletal muscle necrosis in a compartment syndrome animal model. to study whether intermittent exposure to hyperbaric oxygen augments antivenin therapy in reducing muscle necrosis, we injected sublethal doses of western diamondback rattlesnake (crotalus atrox) venom intramuscularly into the hind legs of new zealand white rabbits. in this pilot study, the animals were divided into three treatment groups. the first group received one ...	1989	2757285
platelet-aggregation is stimulated by lactose-inhibitable snake venom lectins.	five lactose-specific lectins from snake venoms were tested for the ability to stimulate the aggregation of human platelets. three of the lectins, bushmaster (lachesis muta), cottonmouth (ancistrodon piscivorous leukostoma) and rattlesnake (crotalus atrox) lectins, consistently stimulated secretion and aggregation. thrombolectin (bothrops atrox) occasionally caused aggregation. copperhead (agkistrodon contortrix contortrix) lectin did not by itself cause platelet aggregation. lactose, a specific ...	1989	2530646
rattlesnake and scorpion antivenoms from the egg yolks of immunized hens.	antivenoms used to treat poisonous bites and stings are usually derived from horse sera. consequently, they contain horse immunoglobulins, which frequently cause complement mediated side effects, and other proteins that can cause serum sickness and, occasionally, anaphylactic shock. here we describe a new, avian source of antivenoms that precludes these complications, and an efficient and gentle means for preparing antivenoms composed solely of venom-specific antibodies. we demonstrate that anti ...	1990	1366776
interaction of hemorrhagic metalloproteinases with human alpha 2-macroglobulin.	the interaction between four crotalus atrox hemorrhagic metalloproteinases and human alpha 2-macroglobulin was investigated. the proteolytic activity of the hemorrhagic toxins ht-c, -d, and -e against the large molecular weight protein substrates, gelatin type i and collagen type iv, was completely inhibited by alpha 2-macroglobulin. the proteolytic activity of ht-a against the same substrates was not significantly inhibited. each mole of alpha 2-macroglobulin bound maximally 2 mol of ht-e and 1 ...	1990	1692735
molecular dynamics simulations of phospholipases a2.	an extensive molecular dynamics study of phospholipases a2 from pancreatic bovine and crotalus atrox venom has shown that the well-conserved homologous core of the phospholipases a2, including the so called catalytic network, is very stable during the course of the calculations. the fluctuations which occur are located in segments which have significantly different three-dimensional conformations in the two phospholipases a2 studied, suggesting that a particularly stable core conformation gives ...	1990	2075191
dimeric character of a basic phospholipase a2 from cobra venom: experimental and modelling study.	when it is gel filtered on sephadex in the absence of calcium ions, basic phospholipase a2 from naja nigricollis venom elutes as a dimer. in order to study the possibility of this dimerization from a structural point of view, three-dimensional models of both monomeric and dimeric n. nigricollis phospholipases a2 have been graphically built on the basis of homologies with the phospholipases a2 from pancreatic bovine and crotalus atrox venom. the building of a dimeric model is made possible by the ...	1990	2075192
isoforms of a highly specific b beta-chain fibrinogenase from the venom of crotalus atrox: preliminary observations.	three variants of a crotalus atrox venom enzyme that cleaves primarily the arg42 - ala bond of the b beta-chain of human fibrinogen were separated by high-performance liquid chromatography and were shown by n-terminal sequence analysis to be amino acid isoforms. all are single-chain glycoproteins whose approximate molecular weights lie between 26,000 and 28,000. the isoenzymes also cleaved the a alpha-chain at arg491 - his, though much more weakly, with strengths for both bonds that varied among ...	1990	2133222
kinetics of the hydrolysis of mixed micelles of dipalmitoyllecithin with triton x-100 catalyzed by a phospholipase a2 from the venom of agkistrodon halys blomhoffii.	the ph dependence of kinetic parameters for the hydrolysis of mixed micelles of 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine (dic16pc) with triton x-100, catalyzed by the intact and the n-terminal alpha-nh2-modified phospholipases a2 (pla2s) of agkistrodon halys blomhoffii, was studied at 25 degrees c and ionic strength 0.1 in the presence of saturating amounts of ca2+. the ph dependence of the kinetic parameters for the hydrolysis of monodispersed dic6pc, catalyzed by the modified enzyme, was ...	1990	2229006
structure of an engineered porcine phospholipase a2 with enhanced activity at 2.1 a resolution. comparison with the wild-type porcine and crotalus atrox phospholipase a2.	the crystal structure of an engineered phospholipase a2 with enhanced activity has been refined to an r-factor of 18.6% at 2.1 a resolution using a combination of molecular dynamics refinement by the gromos package and least-squares refinement by tnt. this mutant phospholipase was obtained previously by deleting residues 62 to 66 in porcine pancreatic phospholipase a2, and changing asp59 to ser, ser60 to gly and asn67 to tyr. the refined structure allowed a detailed comparison with wild-type por ...	1990	2254938
comparison of the immunogenicity and antigenic composition of several venoms of snakes in the family crotalidae.	crude venoms from the prairie rattlesnake (crotalus viridis viridis), the western diamondback rattlesnake (crotalus atrox), the eastern diamondback rattlesnake (crotalus adamanteus) and the timber rattlesnake (crotalus horridus horridus) were used to prepare monovalent antivenoms in rabbits. each of these four monovalent antivenoms was reacted against six different venoms using the technique of immunoblotting (western blot) to determine the relative immunogenicity of the four venoms and to compa ...	1990	2339435
kinetic and inhibition studies of phospholipase a2 with short-chain substrates and inhibitors.	the action of the phospholipases a2 (pla2s) from naja naja naja, naja naja atra, and crotalus atrox venoms as well as the enzyme from porcine pancreas on a number of short-chain, water-soluble substrates was studied. the inhibition of these enzymes by short-chain phosphonate- and thiophosphonate-containing phospholipid analogues was also examined. the kinetic patterns observed for the action of the venom pla2s on substrates containing phosphocholine head groups all deviated from a classical mich ...	1990	2383571
primary structure of a hemorrhagic metalloproteinase, ht-2, isolated from the venom of crotalus ruber ruber.	crotalidae and viperidae snake venoms contains several kinds of metalloproteinases which cause localized hemorrhage by direct action on blood vessel walls. we report here the entire amino acid sequence and the disulfide bridge locations of ht-2, one of the hemorrhagic toxins isolated from the venom of crotalus ruber ruber (red rattlesnake). the non-reduced protein was first cleaved at methionine residues to provide a set of 8 fragments, which covered the entire sequence of ht-2. the disulfide br ...	1990	2081731
the complete amino acid sequence of the high molecular mass hemorrhagic protein hr1b isolated from the venom of trimeresurus flavoviridis.	hemorrhage is a common occurrence in a victim bitten by crotalid and viperid snakes, and hemorrhagic components in these various venoms have been isolated and characterized. previously, we have shown that a low molecular weight hemorrhagic protein (hr2a, 202 amino acid residues) isolated from the venom of trimeresurus flavoviridis is a member of a new subfamily of metalloproteinases. we now report the complete amino acid sequence of a high molecular mass hemorrhagic protein isolated from the sam ...	1990	2398046
glycerol monoethers in the scent gland secretions of the western diamondback rattlesnake (crotalus atrox; serpentes, crotalinae).	1-o-monoalkylglycerols with c12 to c20 chains were identified in the scent gland secretions of the western diamondback rattlesnake (crotalus atrox). this is the first documentation of these compounds in the skin secretions of a reptile.	1990	2373208
hydrolysis of supported pyrenephospholipid monolayers by phospholipase a2.	hydrolysis by pancreatic and snake venom (crotalus atrox) phospholipase a2 of fluorescent monolayers of pyrene-labelled phosphatidylglycerol on solid support was studied. we used a fluorescence microscope equipped with video camera, video recorder and an image analyzer to monitor changes in fluorescence. decrease in pyrene excimer emission was evident when pyrene phosphatidylglycerol monolayers transferred onto quartz glass slides (at a surface pressure of 15 mn m-1) were subjected to enzymatic ...	1990	2208445
identification of the cleavage sites by a hemorrhagic metalloproteinase in type iv collagen.	type iv collagen, solubilized from engelbreth-holm-swarm (ehs) tumor basement membranes is digested by a hemorrhagic metalloproteinase, ht-e, isolated from the crude venom of the western diamondback rattlesnake, crotalus atrox. the major proteolytic products have mr 141,000, 132,000, 87,000, 71,000, 33,000 and approximately 18,000 as estimated by sds-gel electrophoresis of pepsinized type iv collagen fragments. sequence analysis of the digestion products reveal that the mr 141,000, 71,000 and ap ...	1990	2374521
south american snake venom proteins antigenically related to bothrops asper myotoxins.	1. the presence of proteins antigenically related to bothrops asper myotoxins in various snake venoms, mainly from south america, was investigated by using polyclonal and monoclonal antibodies. 2. myotoxin-like components were detected in ten bothrops venoms from south america, and in the venoms of crotalus atrox (north america), trimeresurus flavoviridis (japan), and micrurus alleni (costa rica). 3. cross-reactive components detected in several bothrops venoms show a common subunit of 15-16 kda ...	1990	1710160
snake venom or antivenom induced urticaria.	an amateur herpetologist developed chills, diaphoresis and generalized urticaria 5 h after receiving antivenin (crotalidae) polyvalent (wyeth) for treatment of rattlesnake (crotalus atrox) envenomation. the patient had been bitten 8 mo earlier by a copperhead (agkistrodon contortrix mokeson) resulting in minimal envenomation. he also had been skin testing himself for 6 mo with both diluted crotalus atrox venom and antivenin (crotalidae) polyvalent (wyeth) to determine how sensitive he was to ant ...	1991	1858314
external na+ is not required for ca2+ mobilization in platelets stimulated with rattlesnake lectin or alpha-thrombin.	the effects of extracellular sodium on platelet aggregation and calcium mobilization in platelets stimulated with either rattlesnake (crotalus atrox) lectin (rsl) or alpha-thrombin were compared. the absence of extracellular sodium had no effect on platelet aggregation or calcium mobilization in response to all levels of rsl tested. in contrast platelet aggregation was sodium-dependent in response to less than or equal to .2 units/ml alpha-thrombin. surprisingly, calcium mobilization occurred in ...	1991	1805450
effect of inadequate antivenin stores on the medical treatment of crotalid envenomation.	the case of a 27-y-old male with a serious crotalus atrox envenomation is presented. his medical care was compromised by the lack of readily available polyvalent crotalidae antivenin. an investigation of antivenin stocking by health care facilities in arizona was undertaken. failure to stock sufficient quantities of antivenin to initiate treatment of a single patient with a severe envenomation was found in 43.5% of urban hospitals, 41.2% of rural hospitals within 25 miles of another hospital, 52 ...	1991	1858308
monolayers of long chain lecithins at the air/water interface and their hydrolysis by phospholipase a2.	the behavior of phosphatidylcholine monolayers at the air/water interface was studied by measuring their surface isotherm, surface potential, surface viscosity, and rate of hydrolysis by the dimeric phospholipase a2 from the venom of crotalus atrox. the monolayers showed typical liquid-expanded behavior. in this phase, the surface potential was linearly dependent on surface concentration and extrapolated at zero concentration to a value characteristic of a liquid hydrocarbon/water interface. the ...	1991	1999420
complete primary structure of a galactose-specific lectin from the venom of the rattlesnake crotalus atrox. homologies with ca2(+)-dependent-type lectins.	the complete primary structure of a galactose-specific lectin contained in the venom of the rattlesnake, crotalus atrox, was determined. the lectin is composed of two covalently linked, identical subunits, each consisting of 135 amino acid residues. under physiological conditions the lectin proved to be highly aggregated. the venom lectin contained 9 half-cystines, 8 of which formed four intrasubunit disulfide bridges (cys3-cys14, cys31-cys131, cys38-cys133, and cys106-cys123), while cys86 was i ...	1991	1989986
polymerization site in the beta chain of fibrin: mapping of the b beta 1-55 sequence.	the formation of a fibrin clot occurs through binding of putative complementary sites, called fibrin polymerization sites, located in the nh2- and cooh-terminal domains of fibrin monomer molecules. in this study, we have investigated the structure of the nh2-terminal fibrin polymerization site by using fibrinogen-derived peptides and fragments. fibrinogen was digested with crotalus atrox protease iii, to two major molecular species: a mr 325,000 derivative (fg325) and a peptide of mr 5000. the p ...	1991	1988018
proteolytic digestion of non-collagenous basement membrane proteins by the hemorrhagic metalloproteinase ht-e from crotalus atrox venom.	hemorrhagic toxin e (ht-e), a metalloproteinase isolated from the venom of the western diamondback rattlesnake crotalus atrox, digests laminin and nidogen, both in their isolated forms and when present in a purified soluble complex. the only common site of cleavage by ht-e of isolated nidogen and nidogen when complexed with laminin is at amino acid residue 336 in the amino terminal domain. additionally, nidogen in complex with laminin is also cleaved at sites 322, 351 and 840 as determined by se ...	1991	1801753
antihemorrhagic factors from the blood serum of the western diamondback rattlesnake crotalus atrox.	several antihemorrhagic factors isolated from c. atrox serum are glycoproteins with mol. wt ranging from 65,000 to 80,000. the antihemorrhagic activity of these factors was stable at a ph range of 1.3-11.5 and at temperatures up to 85 degrees c, for 30 min. the isolated antihemorrhagins also neutralized the proteolytic activity of c. atrox venom, as tested with azocollagen and gelatin, and formed a complex with hemorrhagic toxin e isolated from the same venom. the neutralization capacity of the ...	1991	1656547
effects of ph and calcium ion on self-association properties of two dimeric phospholipases a2.	the monomer-dimer equilibria of the dimeric phospholipases a2 from crotalus atrox and agkistrodon piscivorus piscivorus venoms were examined chromatographically as a function of ph and in the presence versus absence of the essential cofactor, calcium ion. at neutral ph without calcium, the subunits of both enzymes reequilibrated sufficiently slowly that dimer and monomer were separated by size exclusion chromatography. at ph 4.2 and lower, the dimers underwent rapid dissociation and reassociatio ...	1991	1885568
suicide-inhibitory bifunctionally linked substrates (siblinks) as phospholipase a2 inhibitors. mechanistic implications.	novel phospholipids that function as mechanism-based inhibitors for phospholipase a2 (pla2) are described. pla2-catalyzed hydrolysis of the sn-2 ester of these suicide-inhibitory bifunctionally linked substrates (siblinks) followed by a cyclization reaction generates a cyclic anhydride at the active site of the enzyme which leads to inhibition. structure/activity relationships for the siblinks substituents in the sn-1 and sn-2 position are delineated. time courses and efficiency of siblinks inhi ...	1991	2002046
proteolysis of interleukin-2, interferon and immunoglobulin by venoms.	limited proteolysis by venoms was analysed by the cleaved peptide band(s) in sds-polyacrylamide gel electrophoresis. the venom from crotalus atrox degraded interferon, interleukin-2, igg, igm, and a crude form of acetyl cholinesterase but had no effect on iga. although the venom from androctonus australis did not exert appreciable proteolysis on any of the immunoglobulins it had potent proteolytic activities against interferon and interleukin-2. the venom from vespula maculifrons had only a mino ...	1991	1724747
adaptability of restrained molecular dynamics for tertiary structure prediction: application to crotalus atrox venom phospholipase a2.	in order to assess the adaptability and/or applicability of the restrained molecular dynamics (rmd) simulation for building a possible tertiary structure of a protein from the x-ray crystal structure of a family reference protein, the tertiary structure prediction of crotalus atrox venom phospholipase a2 (pla2) was attempted based on the x-ray crystal structure of bovine pancreatic pla2. for the formation of secondary and tertiary structures from the fully extended starting structure, the rmd si ...	1991	1881869
comparison of the catalytic properties of phospholipase a2 from pancreas and venom using a continuous fluorescence displacement assay.	phospholipases a2 from pig pancreas and the venoms from bee, naja naja and crotalus atrox have been studied by using a new continuous fluorescence displacement assay that utilizes normal phospholipid substrates [wilton (1990) biochem. j. 266, 435-439]. with limiting amounts of substrate, the assay demonstrated stoichiometric conversion into products with both pancreatic and venom enzymes, and thus would allow phospholipid determination at concentrations down to about 0.1 microm. the substrate sp ...	1991	1898370
immunological properties of the fibrinolytic enzyme (fibrolase) from southern copperhead (agkistrodon contortrix contortrix) venom and its purification by immunoaffinity chromatography.	an antibody to the fibrinolytic enzyme in southern copperhead venom was produced by immunizing rabbits with chromatographically purified enzyme. the antibody was purified from rabbit blood by ammonium sulfate fractionation and protein-a affinity chromatography. the purified antibody reacted only with the fibrinolytic enzyme in southern copperhead venom as demonstrated by immunodiffusion and immunoelectrophoresis. western immunoblotting revealed that several snake venoms, including agkistrodon pi ...	1991	1926169
neutralization of kinin-releasing enzymes of crotalid venoms by monospecific and polyspecific antivenoms.	the amounts of kinin-releasing enzymes in the venoms of crotalus atrox, crotalus adamanteus, crotalus scutulatus scutulatus and agkistrodon piscivorus piscivorus were measured by determining the amounts of kinin released from a sheep kininogen substrate by means of a specific radioimmunoassay. four monospecific and two commercial polyspecific antivenom igg samples were tested for their ability to reduce the kinin-releasing activities of the four crotalid venoms measured in vitro. all of the anti ...	1991	1926178
an indirect haemolytic assay for assessing antivenoms.	dilutions of antivenom, venom, human erythrocytes and a phosphatidylcholine suspension, were incubated for 30 min at 37 degrees c. after centrifugation, the liberated haemoglobin was measured spectrophotometrically. the assay was used to assess an ovine antivenom against the venom from the south american rattlesnake, crotalus durissus terrificus, and an equine wyeth antivenin (crotalidae, polyvalent). the ovine antivenom was more than five times as effective as the equine product. it also neutra ...	1991	1949062
specific binding of crotoxin to brain synaptosomes and synaptosomal membranes.	crotoxin, the presynaptic neurotoxin from crotalus durissus terrificus, was iodinated and used to demonstrate high affinity, specific binding to guinea-pig (cavia porcellus) brain synaptosomes and synaptosomal membrane fragments. 125i-crotoxin binding to the membrane fragments displays two binding plateaus, (kd1 = 4 nm and kd2 = 87 nm, bmax1 = 2 and bmax2 = 4 pmoles/mg membrane protein), but binding to whole synaptosomes revealed only one plateau (kd = 2 nm and bmax = 5 pmoles/mg membrane protei ...	1991	1949068
the hypotensive activity of crotalus atrox (western diamondback rattlesnake) venom: identification of its origin.	viperidae snakes belonging to the genus crotalus, subfamily crotalinae, include the species durissus terrificus, durissus durissus, adamanteus, atrox, cerastes, horridus, molossus, scutulatus, viridis and others. all of them, except for the first 2, are found in north america. crotalus atrox, or diamondback rattlesnakes, live in the southwest united states and in mexico. this paper describes the fractionation of c. atrox venom in order to isolate and identify its hypotensive agents.	1991	2035756
amino acid sequence of a phospholipase a2 from the venom of trimeresurus gramineus (green habu snake).	two phospholipases a2, named phospholipases a2-i and a2-ii, were purified to homogeneity from the venom of trimeresurus gramineus (green habu snake). the complete amino acid sequence of phospholipase a2-i was determined by sequencing the native protein and the peptides produced by enzymatic (achromobacter protease i, clostripain, and chymotrypsin) and chemical (hydroxylamine) cleavages of the s-pyridylethylated derivative of the protein. the protein consisted of 122 amino acid residues and was s ...	1991	2048135
structure of recombinant human rheumatoid arthritic synovial fluid phospholipase a2 at 2.2 a resolution.	phospholipases a2 (pla2s) may be grouped into distinct families of proteins that catalyse the hydrolysis of the 2-acyl bond of phospholipids and perform a variety of biological functions. the best characterized are the small (relative molecular mass approximately 14,000) calcium-dependent, secretory enzymes of diverse origin, such as pancreatic and venom pla2s. the structures and functions of several pla2s are known. recently, high-resolution crystal structures of complexes of secretory pla2s wi ...	1991	2062381
isolation from opossum serum of a metalloproteinase inhibitor homologous to human alpha 1b-glycoprotein.	fractionation of opossum (didelphis virginiana) serum with (nh4)2so4, followed by chromatography on deae-sepharose, phenyl-sepharose, and mono q hr 5/5, has resulted in the isolation in homogeneous condition of a metalloproteinase inhibitor designated oprin (opossum proteinase inhibitor). oprin is a single-chain glycoprotein (26% carbohydrate) with an estimated mr = 52,000, pi = 3.5, and e(1%/1 cm) = 11. oprin inhibited snake venom metalloproteinases, but showed no activity on venom serine prote ...	1992	1731898
[hydrolysis of 5'-phosphonates and nucleoside phosphates by phosphatases of various origin and human and calf serum].	the hydrolysis of 5'-phosphonates of 2'-deoxythymidine and its 3'-modified analogs, inhibiting the hiv reproduction, by the e. coli alkaline, calf intestine and human placenta phosphatases as well as by the crotalus atrox venom 5'-nucleotidase were studied. transformations of 5'-phosphonates of adenosine and its analogs during incubation with human and fetal calf blood sera were investigated. the nucleotide derivatives modified at the phosphate residue were not hydrolyzed by any of the phosphata ...	1992	1335121
comparison of the purity and efficacy of affinity purified avian antivenoms with commercial equine crotalid antivenoms.	antivenoms were raised in laying hens by repeated immunizations with detoxified crotalid snake venoms and purified from egg yolks by affinity chromatography. while the affinity purified avian antivenoms were essentially pure igg, commercial equine (wyeth) and w.h.o. international reference antivenoms (trimeresurus flavoviridis) contained several non-immunoglobulin contaminants. in standard mouse protection assays, the purified avian crotalus atrox and t. flavoviridis antivenoms were 6.3 and 2.0 ...	1992	1440638
evaluation of four different immunogens for the production of snake antivenoms.	four different immunogens were used to produce polyvalent antivenom in rabbits to the venoms of bothrops atrox, crotalus atrox, crotalus adamanteus and crotalus durissus terrificus. the immunogens were: (1) unfractionated mixture of the four crude venoms, and three fractions of the mixture as follows, (2) hplc gel filtration high (> 50,000) mol. wt fraction, (3) hplc gel filtration medium (14,000-50,000) mol. wt fraction, and (4) hplc gel filtration low (< 14,000) mol. wt fraction. the resultant ...	1992	1485332
sequence determination and characterization of a phospholipase a2 isozyme from trimeresurus gramineus (green habu snake) venom.	in addition to phospholipase a2-i (pla2-i) reported previously (oda et al., 1991, toxicon 29, 157), a new pla2 named pla2-ii was isolated from trimeresurus gramineus (green habu snake) venom, and its amino acid sequence was determined by sequencing the native protein and the peptides produced by enzymatic (achromobacter protease i and clostripain) cleavages of the carboxamidomethylated derivative of the protein. the protein consisted of 122 amino acid residues and his-47, asp-48, and asp-98 whic ...	1992	1485333
effects of constriction bands on rattlesnake venom absorption: a pharmacokinetic study.	to determine whether the use of a constriction band alters systemic absorption of rattlesnake venom in pigs and whether constriction band use alters local swelling.	1992	1514719
evidence that a secondary binding and protecting site for factor viii on von willebrand factor is highly unlikely.	a binding domain for factor viii (f.viii) has been previously identified on the n-terminal portion of human von willebrand factor (vwf) subunit [amino acids (aa) 1-272]. in order to characterize other possible structures of vwf involved in its capacity to bind and to protect f.viii against human activated protein c (apc), we used a series of purified vwf fragments overlapping the whole sequence of the subunit. among those were fragments spiii (dimer; aa 1-1365), spii (dimer; aa 1366-2050) and sp ...	1992	1531749
endothelial cell spreading on fibrin requires fibrinopeptide b cleavage and amino acid residues 15-42 of the beta chain.	adhesion and spreading of cultured human umbilical vein endothelial cells on fibrin surfaces of varying structure were characterized to understand better the interactions occurring between endothelium and fibrin at sites of vascular injury. fibrin prepared with reptilase, which cleaves only fibrinopeptide a from fibrinogen, and fibrin prepared with thrombin, which cleaves both fibrinopeptide a and fibrinopeptide b, equally supported endothelial cell adhesion. in contrast, only fibrin made with t ...	1992	1541676
structure of acidic phospholipase a2 for the venom of agkistrodon halys blomhoffii at 2.8 a resolution.	the crystal structure of acidic phospholipase a2 from the venom of agkistrodon halys blomhoffii has been determined by molecular replacement methods based on the known structure of crotalus atrox pla2, a same group ii enzyme. the overall structures, except the calcium-binding regions, are very similar to each other. a calcium ion is pentagonally ligated to two carboxylate oxygen atoms of asp-49 and each carbonyl oxygen atoms of tyr-28, gly-30 and ala-31. a reason why the former enzyme functions ...	1992	1567418
structure-function relationship for the highly toxic crotoxin from crotalus durissus terrificus.	the three-dimensional structure of the highly toxic crotoxin from crotalus durissus terrificus was modelled based on sequence analysis and the refined structure of calcium-free phospholipase of crotalus atrox venom. small-angle x-ray scattering experiments were performed on aqueous solutions of crotoxin. the radial distribution function derived from these scattering experiments and the one calculated from the model structure are in good agreement. crotoxin consists of a basic and an acidic subun ...	1992	1425475
citrate is a major component of snake venoms.	citrate has been identified as a major component of snake venoms by gas liquid chromatography and mass spectrometry. the venoms of bothrops asper, crotalus atrox, crotalus viridis viridis, crotalus adamanteus, sistrurus miliarius barbouri, crotalus horridus horridus, agkistrodon contortrix mokasen, agkistrodon contortrix contortrix and agkistrodon piscivorus piscivorus contain citrate at concentration levels which can serve as effective buffers. calcium, magnesium, zinc, iron, sodium and potassi ...	1992	1626327
isolation of a crotalase-like protease with alpha-fibrinogenase activity from the western diamondback rattlesnake, crotalus atrox.	venom toxins were isolated from rattlesnake (crotalus atrox) venom by cation-exchange chromatography. seven major fractions could be obtained by single-step ion-exchange chromatography with two fractions showing essentially apparent homogeneity by sds-gel electrophoresis. all fractions showed various extents of specific proteolytic activity against alpha- or beta-chains of fibrinogen molecules. further characterization of one of the purified fractions with alpha-fribrinogenase activity indicated ...	1992	1616487
characterization of a protease with alpha- and beta-fibrinogenase activity from the western diamondback rattlesnake, crotalus atrox.	a metalloprotease from the rattlesnake crotalus atrox venom was isolated and purified from multiple-step chromatographies including anion-exchange chromatography, gel permeation and reversed-phase hplc. the fraction was shown to be homogeneous as judged by sds-gel electrophoresis. it also showed a high proteolytic activity against alpha- and beta-chains of fibrinogen molecules. further characterization of the purified fraction with fibrinogenase activity indicated that it is a single-chain prote ...	1992	1520324
sequence of a cdna clone encoding the zinc metalloproteinase hemorrhagic toxin e from crotalus atrox: evidence for signal, zymogen, and disintegrin-like structures.	the sequence of two overlapping cdna clones for the zinc metalloproteinase hemorrhagic toxin e (also known as atrolysin e, ec 3.4.24.44) from the venom gland of crotalus atrox, the western diamondback rattlesnake, is presented. the assembled cdna sequence is 1975 nucleotides in length and encodes an open reading frame of 478 amino acids. the mature hemorrhagic toxin e protein as isolated from the crude venom has a molecular weight of approximately 24,000 and thus represents the processed product ...	1992	1378300
spreading of platelets on fibrin is mediated by the amino terminus of the beta chain including peptide beta 15-42.	we have investigated the adhesion and spreading of platelets on polymerized fibrin of varying structure to identify sites that mediate these interactions. fibrin was prepared with thrombin to remove both fibrinopeptide a (fpa) and fibrinopeptide b (fpb) and with reptilase or agkistrodon contortrix thrombin-like enzyme (acte) to selectively remove fpa or fpb, respectively. residual fibrin-bound enzymes were inhibited with d-phenylalanyl-l-prolyl-l-arginyl chloromethyl ketone (ppack). platelet adh ...	1993	8481515
an examination of structural interactions presumed to be of importance in the stabilization of phospholipase a2 dimers based upon comparative protein sequence analysis of a monomeric and dimeric enzyme from the venom of agkistrodon p. piscivorus.	phospholipases a2 may exist in solution both as monomers and dimers, but enzymes that form strong dimers (kd approximately 10(-9) m) have been found, thus far, only in venoms of the snake family crotilidae. the complete amino acid sequences of a basic monomeric and an acidic dimeric phospholipase a2 from agkistrodon piscivorus piscivorus (american cottonmouth water moccasin) venom have been determined by protein sequencing methods as part of a search for aspects of structure contributing to form ...	1993	8489705