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Lind P, Eaker D. Amino-acid sequence of the alpha-subunit of taipoxin, an extremely potent presynaptic neurotoxin from the Australian snake taipan (Oxyuranus s. scutellatus). EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 124:441-7. [PMID: 7049694 DOI: 10.1111/j.1432-1033.1982.tb06612.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The amino acid sequence of the alpha-subunit of taipoxin, an extremely potent presynaptic neurotoxin from the Australian snake taipan has been determined. The very basic protein, by itself a moderately neurotoxic phospholipase, consists of a single polypeptide chain of 119 amino acids. The main fragmentation of the reduced and S-carboxymethylated derivative was accomplished by cleavage with Staphylococcus aureus V8 protease and trypsin. Chymotryptic peptides and cyanogen bromide fragments were used to align and complete the sequence, which was determined by automated Edman degradation. The taipoxin alpha-subunit is closely homologous to the other taipoxin subunits and to other elapid snake venom phospholipases A2.
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52
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Esquerda JE, Solsona C, Marsal J. Binding of beta-bungarotoxin to Torpedo electric organ synaptosomes. A high resolution autoradiographic study. Neuroscience 1982; 7:751-8. [PMID: 7070671 DOI: 10.1016/0306-4522(82)90080-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Isolated pure cholinergic synaptosomes from Torpedo electric organ were incubated in vitro with beta-bungarotoxin for 15, 30 and 60 min and processed for electron microscopy. It was found that no morphological damage was seen after 15 min but by contrast, severe disruption of synaptosomes was present at 30 or 60 min after incubation with toxin. Synaptosomes were incubated also for 15 min in the presence of 125I-labelled beta-bungarotoxin and the binding was evaluated by electron microscopic autoradiography. The toxin was found to bind to the presynaptic membrane. The surface density of toxin binding sites was calculated to be around 3000/micron2. In a minor population of synaptosomes, the toxin was translocated into large vesicles suggesting that the toxin-receptor complexes underwent endocytosis in such vesicles. These results give further support to the view that inhibition of transmitter release by the toxin is produced by its action on plasma membrane.
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Viljoen CC, Botes DP, Kruger H. Isolation and amino acid sequence of caudoxin, a presynaptic acting toxic phospholipase A2 from the venom of the horned puff adder (Bitis caudalis). Toxicon 1982; 20:715-37. [PMID: 7135414 DOI: 10.1016/0041-0101(82)90120-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A presynaptic acting toxic phospholipase A2, designated caudoxin, was purified from the venom of Bitis caudalis by a combination of gel filtration and ion-exchange chromatography. The specificity of the enzyme was shown to be of the A2 type. The enzyme contains 121 amino acid residues in a single chain and is cross-linked by seven disulfide bridges. Application of cyanogen bromide cleavage and digestion with trypsin and chymotrypsin yielded peptides providing the necessary overlaps to complete derivation of the sequence. Structural features of caudoxin in relation to other toxic and non-toxic phospholipases A2 are discussed.
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54
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Maggio B, Cumar FA, Caputto R. Molecular behaviour of glycosphingolipids in interfaces. Possible participation in some properties of nerve membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 650:69-87. [PMID: 7037053 DOI: 10.1016/0304-4157(81)90001-0] [Citation(s) in RCA: 107] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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55
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Hyatt MC, Russell JA. Effects of beta-bungarotoxin and taipoxin on contractions of canine airways caused by nerve stimulation. Life Sci 1981; 29:1755-9. [PMID: 7300571 DOI: 10.1016/0024-3205(81)90185-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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56
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Abdul-Ghani AS, Coutinho-Netto J, Bradford HF, Summers BA, Thompson EJ. Effect of beta-bungarotoxin on the release of endogenous amino aids from the sensorimotor cortex. J Neurochem 1981; 37:251-4. [PMID: 7252509 DOI: 10.1111/j.1471-4159.1981.tb05317.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
beta-Bungarotoxin, a snake neurotoxin purified from the venom of Bungarus multicinctus, caused a significant increase in the in vivo release of glutamate from the superfused sensorimotor cortex of awake animals. A smaller effect on GABA release was observed, but no change was detected in the release of six other amino acids measured. The effects on glutamate and GABA release were entirely blocked by tetrodotoxin (1 micrometer) and were reversible when the cortical tissue was washed with saline.
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57
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Alderdice MT, Volle RL. Multiple actions of beta-bungarotoxin on acetylcholine release at amphibian motor nerve terminals. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1981; 316:126-30. [PMID: 6972488 DOI: 10.1007/bf00505305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The action of beta-bungarotoxin (beta-BuTX) on spontaneous transmitter release, as monitored by miniature endplate potential (MEPP) frequency, and nerve-stimulated release, which relates directly to endplate potential (EPP) amplitude, was studied at frog sciatic nerve-sartorius muscle junctions. Three phases were found for both spontaneous and evoked release: a transient decrease followed by an increase and a later decrease leading to complete failure. The initial inhibitory phase for both spontaneous and neurally-evoked release occurred at the same time and was independent of stimulation frequency. Both the excitatory and late inhibitory phases for both types of release had a more rapid onset when stimulation frequency was increased, with the effects on evoked release occurring more rapidly than the effects on spontaneous release. Even though EPP amplitude decreased to low levels while MEPP frequency was still high, EPPs did not completely fail until the MEPPs had also declined to very low levels. In elevated K+ solutions, the number of quanta released after toxin application was only about half that released during the control experiment. During the terminal part of the late inhibitory phase of beta-BuTX action on MEPP frequency, no effect or only small transient increases were observed after La3+ administration, elevated [K+]0, or increased osmotic pressure. The present study suggests that depolarization of nerve terminals by the toxin is responsible for initiation of the excitatory phases of both types of release followed by inhibition of nerve-evoked release, and then depletion of vesicular transmitter accounts for the eventual disappearance of both MEPPs and EPPs.
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58
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Gundersen CB, Jenden DJ. Alterations of acetylcholine and choline metabolism in mammalian preparations treated with beta-bungarotoxin. J Neurochem 1981; 36:938-48. [PMID: 7205284 DOI: 10.1111/j.1471-4159.1981.tb01685.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We have studied the effects of beta-bungarotoxin on acetylcholine and choline metabolism in central and peripheral cholinergic preparations using a gas chromatographic-mass spectrometric assay for acetylcholine and choline. In contrast with previous reports, beta-Bungarotoxin did not inhibit the high-affinity uptake of labeled choline or the synthesis of acetylcholine in rat brain synaptosomal fractions. However, the toxin did cause a significant increase of medium choline when it was incubated with synaptosomal fractions. This increase of endogenous choline in the medium may account for the previously reported inhibition of choline uptake because of a dilution of the specific activity of the labeled choline in the medium. Several experiments are reported in which a further characterization was made of the effect of beta-bungarotoxin on medium choline. beta-Bungarotoxin was also shown to cause a large increase of acetylcholine release from rat brain minces and a depletion of the acetylcholine content of minces. A similar phenomenon was found in diaphragm preparations that were exposed continuously to beta-bungarotoxin. However, diaphragms that were treated for only 30 min with toxin showed the previously reported increase of acetylcholine content. beta-bungarotoxin did not have any measurable effect on acetylcholine turnover in smooth muscle preparations from guinea pig ileum. These results help to explain certain inconsistencies in the literature regarding the action of beta-bungarotoxin.
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59
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Ng RH, Howard BD. Inhibition by neurotoxic phospholipases A2 of synaptosomal uptake of gamma-aminobutyric acid. J Neurochem 1981; 36:310-2. [PMID: 7463056 DOI: 10.1111/j.1471-4159.1981.tb02412.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A comparison has been made of the abilities of several neurotoxic and nontoxic phospholipases A2 from snake venoms to inhibit the intake of gamma-aminobutyric acid into synaptosomes from rat cerebral cortex. The neurotoxic phospholipase A2 inhibited GABA uptake more than the nontoxic enzymes did. However, there was a poor correlation between the measured specific enzyme activity of a phospholipase A2 and its ability to inhibit the uptake of GABA.
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60
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Gundersen CB, Jenden DJ, Newton MW. Beta-bungarotoxin stimulates the synthesis and accumulation of acetylcholine in rat phrenic nerve diaphragm preparations. J Physiol 1981; 310:13-35. [PMID: 7230031 PMCID: PMC1274726 DOI: 10.1113/jphysiol.1981.sp013535] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
1. The effects of beta-bungarotoxin on acetylcholine (ACh) synthesis, tissue content and release have been studied in the rat diaphragm. A gas chromatographic mass spectrometric assay was used to measure ACh and choline. 2. Within 30 min, beta-bungarotoxin (0.14 or 1.4 micrograms/ml.) caused a significant increase in tissue ACh content. This increase was apparent prior to the final inhibition by beta-bungarotoxin of evoked (10 Hz) ACh release. 3. The toxin enhanced the incorporation of [2H4]Ch into [2H4]ACh in both resting and stimulated preparations. 4. Hemicholinium-3 blocked the rise in diaphragm ACh normally produced by beta-bungarotoxin. 5. Beta-Bungarotoxin did not directly activate choline acetyltransferase in muscle homogenates. 6. The toxin-induced rise in tissue ACh was largely absent in Ca2+-free solutions which contained either EGTA (1 mM) or SrCl2 (2 or 10 mM). 7. Non-neurotoxic phospholipases A2, fatty acids and the neurotoxic phospholipase A2, notexin, did not cause ACh accumulation in the diaphragm. 8. Beta-Bungarotoxin did not stimulate ACh synthesis in denervated muscle. 9. The extra ACh which accumulated after beta-bungarotoxin did not contribute to enhanced release by nerve impulses even when 4-aminopyridine was added to the medium. High K+ solution and black widow spider venom were also ineffective in increasing output from toxin-treated diaphragms relative to controls that had not been treated with beta-bungarotoxin. 10. Prior injection of a rat with botulinum toxin prevented the accumulation of ACh due to beta-bungarotoxin. Tubocurarine, however, did not antagonize beta-bungarotoxin. 11. These data indicate that beta-bungarotoxin has a unique capacity to inhibit ACh release and stimulate ACh synthesis in diaphragm nerve endings. The results are discussed in terms of a possible action of beta-bungarotoxin to raise the level of ionized Ca in the nerve terminal cytosol.
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61
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62
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The morphology of rat soleus neuromuscular junctions treated in vitro with purified β-bungarotoxin. Brain Res 1980. [DOI: 10.1016/s0006-8993(80)80030-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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63
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Lind P, Eaker D. complete amino-acid sequence of a non-neurotoxic, non-enzymatic phospholipase A2 homolog from the venom of the Australian tiger snake Notechis scutatus scutatus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 111:403-9. [PMID: 7007039 DOI: 10.1111/j.1432-1033.1980.tb04954.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The complete amino acid sequence of Notechis II-1, a non-neurotoxic, non-enzymatic phospholipase A2 homolog from the venom of the Australian tiger snake Notechis s. scutatus has been determined. The protein consists of a single chain of 119 amino acids. The main fragmentation of the reduced and S-carboxymethylated derivative was accomplished by cleavage with Staphylococcus aureus V8 protease. Tryptic peptides were used to align and complete the sequence, which was determined mainly by automated Edman degradation. Notechis II-1 contains all of the residues that appear to be invariant in elapid and pancreatic phospholipases A2 except at position 30 in the sesquence, where an otherwise invariant glycine is replaced by serine.
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64
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Yang CC, King K. Chemical modification of the histidine residue in basic phospholipase A2 from the venom of Naja nigricollis. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 614:373-88. [PMID: 7407195 DOI: 10.1016/0005-2744(80)90227-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Phospholipase A2 from Naja nigricollis venom was separated into three fractions by chromatography on a column of CM-Sephadex C-25. The pI values of fractions CMS-5, CMS-6 and CMS-9 were determined to be 7.6, 8.3 and 10.6, respectively. Fraction CMS-9 was further purified on a DEAE-Sephacel column and the homogeneity was verified. The specific activity of CMS-9 was found to be 1300 units per mg and lethal toxicity 0.3 mg per kg mouse. The most basic and toxic fraction, CMS-9, was subjected to chemical modification with p-bromophenzcyl bromide. The enzyme lost both the enzyme activity and lethal toxicity, however, the antigenicity remained unchanged. Although both 8-anilinonaphthalenesulfonate and Ca2+ showed pronounced protection on the inactivation process, the mechanism of 8-anilinonaphthalene-sulfonate protection is different from that of Ca2+. Amino acid analysis showed that only one (His-47) out of three histidine residues was modified. Although both native and His-modified CMS-9 were perturbed by the presence of Ca2+, the modified enzyme lost the characteristic tryptophan blue shift suggesting that the modified enzyme is unable to exert a charge effect upon Ca2+ binding in the vicinity of the tryptophan group. Scatchard plots revealed only one type of binding sites for 8-anilinonaphthalenesulfonate in the presence of Ca2+. On the other hand, the modified enzyme lost the ability to bind 8-anilinonaphthalene. It is suggested tentatively that the hydrophobic pocket in which 8-anilinonaphthalenesulfonate is bound may be the site of the enzyme that interacts with phospholipid.
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65
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Abe T, Alemá S, Miledi R. On the purification of beta-bungarotoxin. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. SERIES B, BIOLOGICAL SCIENCES 1980; 207:487-90. [PMID: 6104814 DOI: 10.1098/rspb.1980.0036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
It has recently been claimed that our beta-bungarotoxin preparation contained three contaminants, including a postsynaptic toxin. We have extended our purification procedure and found no evidence of such contaminants.
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66
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Cumar FA, Maggio B, Caputto R. Neurotransmitter movements in nerve endings. Influence of substances that modify the interfacial potential. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 597:174-82. [PMID: 6102867 DOI: 10.1016/0005-2736(80)90161-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Polysialogangliosides, sulphatides, glycerylmonooleate, unsaturated fatty acids, myelin basic protein and sucrose inhibit the Na+-coupled uptake and induce a Ca2+-dependent release of dopamine from nerve endings. Substances chemically related to those referred to above, such as monosialogangliosides, neutral glycosphingolipids, glycerylmonostearate, saturated fatty acids and albumin, do not show these effects. Mixtures of polysialogangliosides or sulphatides with myelin basic protein or albumin inhibit, to different degrees, the effects of the individual components. The decreased uptake induced by sucrose reverted to control levels upon reduction of the concentration of the perturbing agent. The restoration of the uptake was probably mediated by the Na+-pump reconstituting the transmembrane Na+-gradient necessary for the Na+-coupled cotransport of dopamine. It is suggested that the effects of uptake inhibitor or release inducer agents derive from their ability to decrease the surface potential and modify the molecular organization of phospholipid interfaces which can result in changes of the membrane ionic permeability.
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67
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Napias C, Heilbronn E. Phospholipase A2 activity and substrate specificity of snake venom presynaptic toxins. Biochemistry 1980; 19:1146-51. [PMID: 7370229 DOI: 10.1021/bi00547a017] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Beta-Neurotoxins from certain snake venoms are highly specific toxins acting at the presynaptic side of the neuromuscular junction. In this study biochemical aspects of this high specificity have been investigated. When toxins (notexin and Naja nigricollis basic phospholipase) act on a mixture of subcellular fractions obtained from brain cortex (synaptosomes, myelin, and mitochondria), the synaptosomal fraction is preferentially attacked and shows the highest release of membrane protein. As seen from isolated fractions, however, even the mitochondria are rapidly and strongly attached. Examining the phospholipase A2 activity of the toxin instead of the release of proteins reveals that synaptosomes represent the best substrate. In contrast to nonneurotoxic phospholipases A2, that from neurotoxin preferentially uses synaptosomal phosphatidylcholine as a substrate when pure phospholipids isolated from subcellular fractions are used. A relationship between the cholesterol/phospholipid ratio and the sensitivity to toxin action in the various subcellular fractions was found. These data suggest that the neurotoxic effect is mainly due to the substrate specificity of the beta-neurotoxins. It is suggested that synaptosomal phosphatidylcholine, embedded in a membrane containing a low amount of cholesterol, is a highly specific substrate for beta-neurotoxins.
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68
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Smith CC, Bradford HF, Thompson EJ, MacDermot J. Actions of beta-bungarotoxin on amino acid transmitter release. J Neurochem 1980; 34:487-94. [PMID: 6101613 DOI: 10.1111/j.1471-4159.1980.tb11171.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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69
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Ng RH, Howard BD. Mitochondria and sarcoplasmic reticulum as model targets for neurotoxic and myotoxic phospholipases A2. Proc Natl Acad Sci U S A 1980; 77:1346-50. [PMID: 6929489 PMCID: PMC348491 DOI: 10.1073/pnas.77.3.1346] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Certain neurotoxins and myotoxins from snake venoms have phospholipase A(2) activity (phosphatide 2-acylhydrolase, EC 3.1.1.4), which appears to be necessary for their toxicity. Several of these toxins inhibit the net uptake of Ca(2+) into sarcoplasmic reticulum vesicles and brain mitochondria. We have obtained evidence that the ability to inhibit this Ca(2+) uptake is a mechanistically relevant correlate of the toxicity of these proteins rather than being just a nonspecific consequence of their phospholipase A(2) activity. Two of the toxins, beta-bungarotoxin and notexin, had 5% and 50%, respectively, of the phospholipase A(2) activity of IVa phospholipase A(2)(a nontoxic enzyme), but beta-bungarotoxin was as effective as IVa in inhibiting Ca(2+) uptake into brain mitochondria and notexin was more effective. Each of the myotoxic enzymes substantially inhibited Ca(2+) uptake into sarcoplasmic reticulum, notexin being the most effective in this regard. This ability correlated better with their myotoxic potency than with their phospholipase A(2) activity. beta-Bungarotoxin lost its toxicity but not its measurable phospholipase A(2) activity after modification with ethoxyformic anhydride in the presence of dihexanoylphosphatidylcholine. The modified toxin also lost most of its ability to inhibit Ca(2+) uptake into sarcoplasmic reticulum and brain mitochondria. Sarcoplasmic reticulum vesicles reconstituted from solubilized sarcoplasmic reticulum retained their sensitivity to notexin.
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70
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Spokes JW, Dolly JO. Complete purification of beta-bungarotoxin. Characterization of its action and that of tityustoxin on synaptosomal accumulation and release of acetylcholine. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 596:81-93. [PMID: 7353009 DOI: 10.1016/0005-2736(80)90172-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
beta-Bungarotoxin, a snake venom protein (molecular weight 21 000) that irreversibly blocks release of acetylcholine from nerve terminals, was purified to homogeneity by ion-exchange chromatography and isoelectric focussing. Sodium dodecyl sulphate gel electrophoresis under reducing conditions resolved two subunits of molecular weight 11 400 and 9000. In the presence of deoxycholate, it showed phospholipase activity which was activated by Ca2+ but not Sr2+.beta-Bungarotoxin and tityustoxin, a polypeptide that prolongs the opening of sodium channels, inhibited choline accumulation by synaptosomes purified from rat cortex. Both toxins also induced release of acetylcholine which was maximal in the presence of Ca2+ and showed ED50 values of 5 . 10(8) and 10(6) M, respectively. Unlike tityustoxin, beta-bungarotoxin also induced release of choline and cytoplasmic lactate dehydrogenase from synaptosomes, with similar potency, suggesting that it causes some membrane disruption, following its binding to the membrane. The effects of tityustoxin on both accumulation and release were antagonised by tetrodotoxin, which specifically blocks Na+ channels, indicating that it mediates these effects by depolarization. Thus, these toxins may prove to be useful probes for characterisation of nerve membrane components involved in triggering transmitter release.
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71
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72
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Tse CK, Dolly JO, Diniz CR. Effects of beta-bungarotoxin and tityustoxin on accumulation of putative amino acid neurotransmitters by rat cortex synaptosomes. Neuroscience 1980; 5:135-43. [PMID: 6102747 DOI: 10.1016/0306-4522(80)90079-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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73
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Kamenskaya MA, Satybaldina NK. Action of the presynaptic neurotoxin notechis II-5 from the venom of Notechis scutatus scutatus on mouse motor nerve endings. Bull Exp Biol Med 1979. [DOI: 10.1007/bf00838185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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74
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Fohlman J, Eaker D, Dowdall MJ, Lüllmann-Rauch R, Sjödin T, Leander S. Chemical modification of taipoxin and the consequences for phospholipase activity, pathophysiology, and inhibition of high-affinity choline uptake. EUROPEAN JOURNAL OF BIOCHEMISTRY 1979; 94:531-40. [PMID: 428399 DOI: 10.1111/j.1432-1033.1979.tb12922.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Treatment of taipoxin with p-bromophenacyl bromide resulted in modification of single histidine residues in the alpha and beta subunits. The modification decreased the neurotoxicity (lethality) 350-fold, but the inhibitory action on high-affinity choline transport was reduced only threefold. The phospholipase activity and Ca2+-association constants for taipoxin and its subunits were determined. A model for the neurotoxicity of taipoxin indicates the alpha subunit as the ultimate cause of the disruption of synaptic transmission.
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75
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Donlon M, Shain W, Tobias GS, Marinetti GV. Characterization of an 11,000-dalton beta-bungarotoxin: binding and enzyme activity on rat brain synaptosomal membranes. MEMBRANE BIOCHEMISTRY 1979; 2:367-91. [PMID: 514091 DOI: 10.3109/09687687909063872] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The binding and phospholipase A2 activity of an 11,000-dalton beta-bungarotoxin, isolated from Bungarus multicincutus venom, have been characterized using rat brain subcellular fractions as substrates. 125I-labeled beta-bungarotoxin binds rapidly (k = 0.14 min-1 and 0.11 min-1), saturably (Vmax = 130.1 +/- 5.0 fmoles/mg and 128.2 +/- 7.1) fmoles/mg), and with high affinity (apparent Kd = 0.8 +/- 0.1 nM and 0.7 +/- 0.1 nM) to rat brain mitochondria and synaptosomal membranes, respectively, but not to myelin. The binding to synaptosomal membranes is inhibited by divalent cations and by pretreatment with trypsin. The binding results suggest that the toxin binds to specific protein receptor sites on presynpatic membranes. The 11,000-dalton toxin rapidly hydrolyzes synaptosomal membrane phospholipids to lysophosphatides and manifests relative substrate specificity in the order phosphatidyl ethanolamine greater than phosphatidyl choline greater than phosphatidyl serine. These results indicate that the 11,000-dalton beta-bungarotoxin is a phospholipase A2 and can use presynaptic membrane phospholipids as substrates. The binding, phospholipase activity and other biological properties of the 11,000-dalton toxin are contrasted with those of the beta-bungarotoxin found in highest concentration in the venom (the 22,000-dalton beta-bungarotoxin), and the two toxins are shown to have qualitatively similar properties. Finally the results are shown to support the hypothesis that beta-bungarotoxins act in a two-step fashion to inhibit transmitter release: first, by binding to a protein receptor site on the presynatic membrane associated with Ca2+ entry, and second, by perturbing through enzymatic hydrolyses the phospholipid matrix of the membrane and thereby causing an increase in passive Ca2+ permeability.
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76
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Leonardi TM, Howden ME, Spence I. A lethal myotoxin isolated from the venom of the Australian king brown snake (Pseudechis australis). Toxicon 1979; 17:549-55. [PMID: 524383 DOI: 10.1016/0041-0101(79)90229-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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77
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Magazanik LG, Gotgilf IM, Slavnova TI, Miroshnikov AI, Apsalon UR. Effects of phospholipase A2 from cobra and bee venom on the presynaptic membrane. Toxicon 1979; 17:477-88. [PMID: 516081 DOI: 10.1016/0041-0101(79)90281-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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78
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Tobias GS, Donlon MA, Catravas GN, Shain W. Purification and biochemical characterization of an 11 000-dalton beta-bungarotoxin. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 537:348-57. [PMID: 569500 DOI: 10.1016/0005-2795(78)90518-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The chromatographic separation and biochemical characterization of a beta-bungarotoxin is described. This toxin is isolated as the most basic eluting protein of Bungarus multicinctus venom when separated by column chromatography on CM-Sephadex C-25. The protein migrated as a single band on pH 4.3 and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The molecular weight of this toxin was estimated to be 10 000 +/- 1000 by analytical sedimentation analysis. This value was consistent with the electrophoretic mobility of the toxin in SDS-polyacrylamide gels. The amino acid composition of this 11 000-dalton beta-bungarotoxin was similar to that of the 22 000-dalton beta-bungarotoxin previously reported (Lee et al. (1972) J. Chromatogr. 72, 71--82; Kelly, R.B. and Brown, III, F.R. (1974) J. Neurobiol. 5, 135--150; Kondo et al. (1978) J. Biochem. Tokyo 83, 91--99), suggesting that the 11 000-dalton toxin may be one of the polypeptide chains of the larger toxin. The 11 000-dalton beta-bungarotoxin was toxic to mice when injected intravenously. Animals that received lethal doses exhibited hyperexcitability followed by ataxia, convulsions, and death. The minimum lethal dose was 0.12 microgram/g body weight. This beta-bungarotoxin exhibited Ca2+-dependent phospholipase A activity comparable to that of the 22 000-dalton beta-bungarotoxin. The enzyme exhibited phospholipid substrate specificity in the rank order of phosphatidyl-choline, phosphatidylserine, phosphatidylethanolamine, and phosphatidyl-inositol. The enzyme activity was destroyed by boiling for 3 min at pH 8.6. In addition, an enzymatically inactive quantity of the 11 000-dalton toxin, equivalent to five times the minimum lethal dose of enzymatically active toxin, was not lethal when injected into mice. To test whether phospholipase A activity is responsible for lethality, bee venom phospholipase A2 was injected into mice at similar and greater concentrations with no toxic effect. Thus, while phospholipase A activity may be required for the lethal effect of the 11 000-dalton beta-bungarotoxin, the specificity of action of the toxin is not determined by its enzyme activity.
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MacDermot J, Westgaard RH, Thompson EJ. beta-Bungarotoxin. Separation of two discrete proteins with different synaptic actions. Biochem J 1978; 175:271-9. [PMID: 736897 PMCID: PMC1186063 DOI: 10.1042/bj1750271] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
beta-Bungarotoxin, a specific presynaptic blocking agent, was prepared in two stages from the crude venom of Bungarus multicinctus by ion-exchange chromatography on the weakly acidic ion exchanger, CM-Sephadex, and on the strongly acidic ion exchanger, sulphopropyl-Sephadex. By these procedures it was purified to a single protein, which was shown by reduction to contain two polypeptide chains with mol.wts. of less than 15000. During purification of beta-bungarotoxin three other proteins were isolated. Two of these proteins have similar molecular weights, subunit structure and physiological properties to the major protein component. This latter is referred to as beta-bungarotoxin, since it has the same physiological properties as those described for unpurified beta-bungarotoxin by other workers. The first protein has very different physiological effects and biochemical properties from beta-bungarotoxin. This protein has a single class of polypeptide chains with an apparent molecular weight that is lower than the main beta-bungarotoxin protein, and appears to block synaptic transmission by a predominantly postsynaptic effect. It has been suggested [Oberg & Kelly (1976) J. Neurobiol. 7, 129-141] that the action of beta-bungarotoxin depends on its phospholipase A activity; however, in this preparation of the toxin less than 50 muunits of phospholipase A activity were detected (1 unit of activity is the amount of enzyme forming 1 mumol of L-alpha-phosphatidylcholine/min per mg of protein).
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81
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MacDermot J, Westgaard RH, Thompson EJ. beta-Bungarotoxin. The binding of [3H]pyridoxylated beta-bungarotoxin to a high-molecular-weight protein receptor. Biochem J 1978; 175:281-8. [PMID: 736898 PMCID: PMC1186064 DOI: 10.1042/bj1750281] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
beta-Bungarotoxin was labelled with pyridoxal 5'-phosphate (incorporating 3H). The kinetics of beta-bungarotoxin binding to several tissue subfragments of nervous tissue was studied. The dissociation constant of 3H-pyridoxylated beta-bungarotoxin in this reaction was 0.21-0.37 micron and that of unlabelled beta-bungarotoxin was 25 nM. Hill [(1910) J. Physiol. (London) 40, iv-vii] and Scatchard [(1949) Ann. N.Y. Acad. Sci. 51, 660-672] analyses demonstrated no co-operativity of binding and only a single class of receptor sites, consistent with a bimolecular association of beta-bungarotoxin and its receptor. The iodinated toxin was physiologically inactive. Toxin was bound in non-specific unsaturable fashion by glass and/or plastic. This low-affinity binding was corrected by addition of bovine serum albumin to a final concentration of 30 mg/ml. A soluble protein receptor of beta-bungarotoxin was isolated and the mol.wt. is approx. 200000.
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82
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Pittman R, Oppenheim RW, Chu-Wang IW. beta-Bunungarotoxin induced neuronal degeneration in the chick embryo spinal cord. Brain Res 1978; 153:199-204. [PMID: 679047 DOI: 10.1016/0006-8993(78)91145-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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83
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Sen I, Cooper JR. Similarities of beta-bungarotoxin and phospholipase A2 and their mechanism of action. J Neurochem 1978; 30:1369-72. [PMID: 670979 DOI: 10.1111/j.1471-4159.1978.tb10468.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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84
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Nelson-Krause DC, Howard BD. Energy utilization in the induced release of gamma-aminobutyric acid from synaptosomes. Brain Res 1978; 147:91-105. [PMID: 350351 DOI: 10.1016/0006-8993(78)90774-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Newly accumulated gamma-aminobutyric acid (GABA) was released from synaptosomes by treatment with 30 mM K+ or the Ca2+ ionophore A23187. Release was Ca2+-dependent and energy-dependent. The induced release of GABA was inhibited by S-13, an uncoupler of oxidative phosphorylation, by azide, a blocker of mitochondrial respiration, and by oligomycin, efrapeptin, tributyltin and dicyclohexylcarbodiimide (DCCD), which are inhibitors of Ca2+/Mg2+-ATPases, including mitochondrial ATPase. Efrapeptin blocked GABA release induced by K+ but not A23187-induced release. Azide and oligomycin appeared to inhibit GABA release as a consequence of their effects on mitochondrial ATP synthesis. However, the inhibition of GABA release by the other compounds could not be totally accounted for by their effects on synaptosomal ATP stores. It is proposed that these compounds, in addition to affecting ATP synthesis, directly affect biochemical reactions involved in GABA release. Thus, these and similar inhibitors seem to be useful probes of the transmitter release process.
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85
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Tzeng MC, Siekevitz P. The effect of the purified major protein factor (alpha-latrotoxin) of black widow spider venom on the release of acetylcholine and norepinephrine from mouse cerebral cortex slices. Brain Res 1978; 139:190-6. [PMID: 620349 DOI: 10.1016/0006-8993(78)90073-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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86
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Chen CJ, Chang PL, Shiau SY, Lee CY. Effect of beta-bungarotoxin on acetylcholinesterase activity and ultrastructure of the skeletal muscle isolated from the chick embryo. Toxicon 1978; 16:461-71. [PMID: 694947 DOI: 10.1016/0041-0101(78)90143-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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87
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Habermann E, Breithaupt H. Mini-review. The crotoxin complex--an example of biochemical and pharmacological protein complementation. Toxicon 1978; 16:19-30. [PMID: 622722 DOI: 10.1016/0041-0101(78)90056-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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88
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CHEMISTRY AND BIOCHEMISTRY OF SNAKE VENOM NEUROTOXINS. Toxins (Basel) 1978. [DOI: 10.1016/b978-0-08-022640-8.50029-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] Open
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Hanley MR, Eterović VA, Hawkes SP, Hebert AJ, Bennett EL. Neurotoxins of Bungarus multicinctus vernom. Purification and partial characterization. Biochemistry 1977; 16:5840-9. [PMID: 201279 DOI: 10.1021/bi00645a031] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The purification to homogeneity of nine neurotoxic components of the venom of Bungarus multicinctus is described. The purified components include alpha-bungarotoxin and two other alpha-type synaptic toxins and beta-bungarotoxin and five other beta-type synaptic toxins. The purified toxins have been characterized by electrophoresis, isoelectric focusing, amino acid analysis, and N-terminal amino acid determination. The alpha-type synaptic neurotoxins constitute a discrete class with molecular weights of 7000-8500, isoelectric points (pI) of 9.0-9.2, and N-terminal isoleucine or methionine. The beta-type synaptic neurotoxins constitute a second group with molecular weights of 20 000-22 000 and pI = 8.8-9.7. Fractions 10 through 13 exhibit a chain structure consisting of a 6000-7000 light chain and a 11 000-15 000 heavy chain apparently covalently stabilized by interchain disulfides. Fractions 9A and 14 were single chains of 11 000-14 000 which resemble the sequenced beta-type synaptic neurotoxin notexin (Halpert, J., and Eaker, D. (1975), J. Biol. Chem. 250, 6990). All of the beta-type synaptic toxins have a single tryptophan and N-terminal aspartic acid or asparagine.
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Hawgood BJ, Smith JW. The mode of action at the mouse neuromuscular junction of the phospholipase A-crotapotin complex isolated from venom of the South American rattlesnake. Br J Pharmacol 1977; 61:597-606. [PMID: 202359 PMCID: PMC1668080 DOI: 10.1111/j.1476-5381.1977.tb07553.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
1 Phospholipase A(2)-crotapotin complex (P-C complex) isolated from the venom of Crotalus durissus terrificus induced an irreversible blockade of neuromuscular transmission when twitch tension was measured in the mouse phrenic nerve-hemidiaphragm preparation in vitro at 37 degrees C.2 A similar concentration of the phospholipase A(2) (10 mug/ml) alone did not affect neuromuscular transmission and no priming action was detected on later addition of crotapotin.3 The rate of neuromuscular blockade induced by P-C complex (15 mug/ml) was not altered by raising the frequency of nerve stimulation. Lower temperatures markedly increased the time of onset and reduced the rate of blockade (Q(10) (27-37 degrees C) of 4.4) whilst replacement of Ca by Sr in the medium prevented this activity. These latter results suggest that enzymatic activity is important in the neurotoxicity of the complex.4 A myotoxic action was shown by 30 mug/ml P-C complex and 30 mug/ml phospholipase A(2).5 P-C complex (150 mug) was injected into the tail vein of mice and the intoxicated hemidiaphragm preparation removed for intracellular recording at 25 degrees C.6 In fully intoxicated hemidiaphragms, resting membrane potentials were unaltered and endplate potentials (e.p.ps) varied in average amplitude from zero to less than 3 mV.7 Miniature endplate potential (m.e.p.p.) frequency was lower at fully poisoned endplates than at controls; the frequency rose during a 50 Hz tetanus but was unaffected by either raising external K or the application of the Ca-ionophore A23187.8 E.p.ps were recorded in partially intoxicated hemidiaphragms with (+)-tubocurarine (0.5-1.0 mug/ml) added to prevent contraction. Evoked release was abnormal as 50 Hz tetanus elicited e.p.ps of very variable amplitude, no facilitation of response was shown to paired stimuli, and tetraethylammonium (0.5 mM) failed to increase e.p.p. amplitudes.9 M.e.p.ps and e.p.ps were recorded at partially poisoned endplates in low Ca-high Mg solution. A reduction in the quantal content of evoked transmitter release was observed in comparison with controls.10 M.e.p.ps recorded at partially and at fully intoxicated endplates showed an altered amplitude distribution with a higher proportion of large potentials.11 It is concluded that P-C complex has a presynaptic site of action and may interfere with depolarization-secretion coupling at the motor nerve terminals.
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Abe T, Alemá S, Miledi R. Isolation and characterization of presynaptically acting neurotoxins from the venom of Bungarus snakes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1977; 80:1-12. [PMID: 303565 DOI: 10.1111/j.1432-1033.1977.tb11849.x] [Citation(s) in RCA: 164] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
1. Five presynaptic toxins have been isolated in pure form from the venom of Bungarus multicinctus and Bungarus caeruleus and named beta1, beta2, beta3, beta4, and beta-ceruleotoxin. 2. They differ in electrophoretic mobility and amino acid composition, while all have the same molecular weight (22000) and are composed of two subunits of molecular weight 9000 and 12000. 3. The toxins have phospholipase A activity when assayed with both natural and synthetic phospholipids, and this activity requires the presence of Ca2+ ions. 4. beta-Bungarotoxin (beta3) binds 1 mol of Ca2+ per mol of protein and this binding induces a conformational change as detected by fluorescence measurements in the presence of the dye 8-anilino-1-naphthalene sulfonic acid. 5. The phospholipase activity of all the toxins is lost when a critical histidine residue is modified with p-bromophenacyl bromide. 6. As a result of the modification the lethality of the toxins is greatly reduced. 7. Native toxin causes a rapid decrease in amplitude of end-plate potentials, followed by a transient increase and subsequent decrease, until transmitter release is completely abolished. The modified toxin still causes the early decrease in release but toxin action does not progress to complete block. 8. The rate of blockage of transmitter release by native toxin is reduced in the presence of modified toxin. 9. It is concluded that phospholipase activity plays an important role in the action of this class of toxins at the neuromuscular junction.
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Strong PN, Kelly RB. Membranes undergoing phase transitions are preferentially hydrolyzed by beta-bungarotoxin. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 469:231-5. [PMID: 901785 DOI: 10.1016/0005-2736(77)90187-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
beta-Bungarotoxin preferentially hydrolyzes choline phospholipids (dilauroyl, dimyristoyl, dipalmitoyl) at their respective gel to liquid crystalline phase transition temperatures. Cholesterol markedly reduces the rate of phospholipid hydrolysis; at 0.33 mol percent cholesterol:phospholipid, the toxin's phospholipase activity is completely inhibited.
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Chang CC, Su MJ, Lee JD, Eaker D. Effects of Sr2+ and Mg2+ on the phospholipase A and the presynaptic neuromuscular blocking actions of beta-bungarotoxin, crotoxin and taipoxin. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1977; 299:155-61. [PMID: 198683 DOI: 10.1007/bf00498557] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
1.beta-Bungarotoxin, crotoxin and taipoxin, presynaptic neurotoxins of snake venom origin, have about the same phospholipid-splitting activities as a much less toxic cobra phospholipase A2 in the presence of Ca2+ and deoxycholate. 2. Sr2+ was a much less effective activator of the enzymes than is Ca2+, the activation by Sr2+ being only 3-6% for beta-bungarotoxin and crotoxin and 12% for taipoxin. 3. Sr2+ also inhibited the Ca2+ -activated enzymes by 80% in the cases of beta-bungarotoxin and crotoxin, but only 16% in the case of taipoxin. 4. Mg2" had no significant effect on beta-bungarotoxin or crotoxin, but activated taipoxin in the presence or absence of Ca2". 5. In Sr2+ -Tyrode lacking Ca2+ all three toxins exhibited the same immediate depression followed by facilitation in the rat and mouse diaphragms, but the final blocking activity was only 3-10% with beta-bungarotoxin and crotoxin and was 30% with taipoxin. 6. In Sr2+ -Tyrode, increasing in the rate of nerve stimulation had less accelerating effect on the development of neuromuscular block than in Ca2+ -Tyrode for any of the toxins. 7. Removal of Mg2+ from Sr2+ -Tyrode did not diminish the potency of taipoxin in blocking neuromuscular transmission, suggesting that enzyme activity at the outer surface of the axolemma does not contribute to the neuromuscular blocking action. 8. All of the results indicate that there are close correlations between the presynaptic activities of these toxins and their phospholipid-splitting activities in the cationic environment prevailing in the axoplasm. Apparently the final blocking effect of these toxins is due to phospholipase A action within the nerve terminal.
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Ng RH, Howard BD. Failure of a phospholipase A inhibitor to inhibit beta-bungarotoxin phospholipase A. Brain Res 1977; 120:577-9. [PMID: 832144 DOI: 10.1016/0006-8993(77)90413-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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95
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Howard BD, Truog R. Relationship between the neurotoxicity and phospholipase A activity of beta-bungarotoxin. Biochemistry 1977; 16:122-5. [PMID: 831773 DOI: 10.1021/bi00620a020] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
beta-Bungarotoxin is a protein neurotoxin that exhibits phospholipase A activity. The neurotoxin and phospholipase A activities were similarly affected by several agents that modify proteins in various ways. Both activities were very thermostable and resistant to treatment with proteases, 6 M urea, phenylmethylsulfonyl fluoride, and N-acetylimidazole. Both activities were sensitive to beta-mercaptoethanol, and to N-bromosuccinimide and ethoxyformic anhydride, which previously had been shown to inactivate rattlesnake venom phospholipase A by modifying selective amino acids. Dihexanoyllecithin, which acts as a substrate for the beta-bungarotoxin phospholipase A, and Ca2+ protect the phospholipase A activity against inactivation by ethoxyformic anhydride but not the neurotoxicity. Treatment of intact membranes with proteases reduces hydrolysis of the membranes lipids by the toxin phospholipase A.
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Kannan KK, Lövgren S, Cid-Dresdner H, Petef M. Crystallization and crystallographic data of notexin: a neurotoxic basic phospholipase A from the venom of Australian tiger snake Notechis scutatus scutatus. Toxicon 1977; 15:435-9. [PMID: 906027 DOI: 10.1016/0041-0101(77)90122-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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97
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Chang CC, Lee JD, Eaker D, Fohlman J. Short communications the presynaptic neuromuscular blocking action of taipoxin. A comparison with beta-bungarotoxin and crotoxin. Toxicon 1977; 15:571-6. [PMID: 198917 DOI: 10.1016/0041-0101(77)90108-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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98
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Chang CC, Lee JD. Crotoxin, the neurotoxin of South American rattlesnake venom, is a presynaptic toxin acting like beta-bungarotoxin. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1977; 296:159-68. [PMID: 834316 DOI: 10.1007/bf00508469] [Citation(s) in RCA: 105] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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99
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Halpert J, Eaker D. Isolation and amino acid sequence of a neurotoxic phospholipase A from the venom of the Australian tiger snake Notechis scutatus scutatus. J Biol Chem 1976. [DOI: 10.1016/s0021-9258(17)32855-7] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Halpert J, Eaker D. Isolation of a non-neurotoxic, non-enzymatic phospholipase A homologue from the venom of the australian tiger snake Notechis scutatus scutatus. FEBS Lett 1976; 72:91-5. [PMID: 992096 DOI: 10.1016/0014-5793(76)80905-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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