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Silva LC, Pucca MB, Pessenda G, Campos LB, Martinez EZ, Cerni FA, Barbosa JE. Discovery of human scFvs that cross-neutralize the toxic effects of B. jararacussu and C. d. terrificus venoms. Acta Trop 2018; 177:66-73. [PMID: 28887121 DOI: 10.1016/j.actatropica.2017.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 08/21/2017] [Accepted: 09/04/2017] [Indexed: 12/16/2022]
Abstract
Accidents involving venomous snakes are a public health problem worldwide, causing a large number of deaths per year. In Brazil, the majority of accidents are caused by the Bothrops and Crotalus genera, which are responsible for approximately 80% of severe envenoming cases. The cross-neutralization of snake venoms by antibodies is an important issue for development of more effective treatments. Our group has previously reported the construction of human monoclonal antibody fragments towards Bothrops jararacussu and Crotalus durissus terrificus' venoms. This study aimed to select human single-chain variable fragments (scFvs) that recognize both bothropic and crotalic crude venoms following venoms neutralizing capacity in vitro and in vivo. The cross-reactivity of Cro-Bothrumabs were demonstrated by ELISA and in vitro and in vivo experiments showed that a combination of scFvs neutralizes in vitro toxic activities (e.g. indirect hemolysis and plasma-clotting) of crotalic and bothropic venoms as well as prolonged survival time of envenomed animals. Our results may contribute to the development of the first human polyvalent antivenom against Bothrops jararacussu and Crotalus durissus terrificus venoms, overcoming some undesirable effects caused by conventional serotherapy.
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Fusco LS, Rodríguez JP, Torres-Huaco F, Huancahuire-Vega S, Teibler P, Acosta O, Marangoni S, Ponce-Soto LA, Leiva LC. P9a(Cdt-PLA2) from Crotalus durissus terrificus as good immunogen to be employed in the production of crotalic anti-PLA2 IgG. Toxicol Lett 2015; 238:7-16. [DOI: 10.1016/j.toxlet.2015.06.528] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 06/18/2015] [Accepted: 06/22/2015] [Indexed: 10/23/2022]
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Gilliam LL, Ownby CL, McFarlane D, Canida A, Holbrook TC, Payton ME, Krehbiel CR. Development of a double sandwich fluorescent ELISA to detect rattlesnake venom in biological samples from horses with a clinical diagnosis of rattlesnake bite. Toxicon 2013; 73:63-8. [PMID: 23834918 DOI: 10.1016/j.toxicon.2013.06.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 06/17/2013] [Accepted: 06/27/2013] [Indexed: 11/26/2022]
Abstract
Rattlesnake bites in horses are not uncommon and the clinical outcomes are widely variable. Treatment of horses with anti-venom is often cost prohibitive and could have negative consequences; therefore, the development of a quantitative test to determine if anti-venom therapy is indicated would be valuable. The objective of this study was to develop an ELISA to detect rattlesnake venom in biological samples from clinically bitten horses. Nineteen horses were enrolled in the study. Urine was available from 19 horses and bite site samples were available from 9 horses. A double sandwich fluorescent ELISA was developed and venom was detected in 5 of 9 bite site samples and 12 of 19 urine samples. In order to determine if this assay is useful as a guide for treatment, a correlation between venom concentration and clinical outcome needs to be established. For this, first peak venom concentration needs to be determined. More frequent, consistent sample collection will be required to define a venom elimination pattern in horses and determine the ideal sample collection time to best estimate the maximum venom dose. This report describes development of an assay with the ability to detect rattlesnake venom in the urine and at the bite site of horses with a clinical diagnosis of rattlesnake bite.
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Affiliation(s)
- Lyndi L Gilliam
- 1 Farm Rd-OSU BVMTH, Department of Veterinary Clinical Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
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Lomonte B. Identification of linear B-cell epitopes on myotoxin II, a Lys49 phospholipase A₂ homologue from Bothrops asper snake venom. Toxicon 2012; 60:782-90. [PMID: 22677805 DOI: 10.1016/j.toxicon.2012.05.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 05/28/2012] [Accepted: 05/29/2012] [Indexed: 12/17/2022]
Abstract
Knowledge on toxin immunogenicity at the molecular level can provide valuable information for the improvement of antivenoms, as well as for understanding toxin structure-function relationships. The aims of this study are two-fold: first, to identify the linear B-cell epitopes of myotoxin II from Bothrops asper snake venom, a Lys49 phospholipase A₂ homologue; and second, to use antibodies specifically directed against an epitope having functional relevance in its toxicity, to probe the dimeric assembly mode of this protein in solution. Linear B-cell epitopes were identified using a library of overlapping synthetic peptides spanning its complete sequence. Epitopes recognized by a rabbit antiserum to purified myotoxin II, and by three batches of a polyvalent (Crotalidae) therapeutic antivenom (prepared in horses immunized with a mixture of B. asper, Crotalus simus, and Lachesis stenophrys venoms) were mapped using an enzyme-immunoassay based on the capture of biotinylated peptides by immobilized streptavidin. Some of the epitopes identified were shared between the two species, whereas others were unique. Differences in epitope recognition were observed not only between the two species, but also within the three batches of equine antivenom. Epitope V, located at the C-terminal region of this protein, is known to be relevant for toxicity and neutralization. Affinity-purified rabbit antibodies specific for this site were able to immunoprecipitate myotoxin II, suggesting that the two copies of epitope V are simultaneously available to antibody binding, which would be compatible with the mode of dimerization known as "conventional" dimer.
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Affiliation(s)
- Bruno Lomonte
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, SJ 11501, Costa Rica.
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Fujii S, Ikeda K, Hayashi K. Catalytic and Toxicity Mechanisms of Secretory Phospholipases A2. ACTA ACUST UNITED AC 2009. [DOI: 10.3109/15569549809040395] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Ferquel E, de Haro L, Jan V, Guillemin I, Jourdain S, Teynié A, d'Alayer J, Choumet V. Reappraisal of Vipera aspis venom neurotoxicity. PLoS One 2007; 2:e1194. [PMID: 18030329 PMCID: PMC2065900 DOI: 10.1371/journal.pone.0001194] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 10/17/2007] [Indexed: 11/23/2022] Open
Abstract
Background The variation of venom composition with geography is an important aspect of intraspecific variability in the Vipera genus, although causes of this variability remain unclear. The diversity of snake venom is important both for our understanding of venomous snake evolution and for the preparation of relevant antivenoms to treat envenomations. A geographic intraspecific variation in snake venom composition was recently reported for Vipera aspis aspis venom in France. Since 1992, cases of human envenomation after Vipera aspis aspis bites in south-east France involving unexpected neurological signs were regularly reported. The presence of genes encoding PLA2 neurotoxins in the Vaa snake genome led us to investigate any neurological symptom associated with snake bites in other regions of France and in neighboring countries. In parallel, we used several approaches to characterize the venom PLA2 composition of the snakes captured in the same areas. Methodology/Principal Findings We conducted an epidemiological survey of snake bites in various regions of France. In parallel, we carried out the analysis of the genes and the transcripts encoding venom PLA2s. We used SELDI technology to study the diversity of PLA2 in various venom samples. Neurological signs (mainly cranial nerve disturbances) were reported after snake bites in three regions of France: Languedoc-Roussillon, Midi-Pyrénées and Provence-Alpes-Côte d'Azur. Genomes of Vipera aspis snakes from south-east France were shown to contain ammodytoxin isoforms never described in the genome of Vipera aspis from other French regions. Surprisingly, transcripts encoding venom neurotoxic PLA2s were found in snakes of Massif Central region. Accordingly, SELDI analysis of PLA2 venom composition confirmed the existence of population of neurotoxic Vipera aspis snakes in the west part of the Massif Central mountains. Conclusions/Significance The association of epidemiological studies to genetic, biochemical and immunochemical analyses of snake venoms allowed a good evaluation of the potential neurotoxicity of snake bites. A correlation was found between the expression of neurological symptoms in humans and the intensity of the cross-reaction of venoms with anti-ammodytoxin antibodies, which is correlated with the level of neurotoxin (vaspin and/or ammodytoxin) expression in the venom. The origin of the two recently identified neurotoxic snake populations is discussed according to venom PLA2 genome and transcriptome data.
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Affiliation(s)
| | - Luc de Haro
- Centre Antipoison, Hôpital Salvator, Marseille, France
| | - Virginie Jan
- Unité des Venins, Institut Pasteur, Paris, France
| | | | | | - Alexandre Teynié
- UENC INRA, Centre de Recherche de Theix, Saint Genes Champanelle, France
| | - Jacques d'Alayer
- Plate-forme d'Analyse et de Microséquençage des Proteines, Institut Pasteur, Paris, France
| | - Valérie Choumet
- Unité des Venins, Institut Pasteur, Paris, France
- * To whom correspondence should be addressed. E-mail:
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Stábeli RG, Magalhães LMP, Selistre-de-Araujo HS, Oliveira EB. Antibodies to a fragment of the Bothrops moojenil-amino acid oxidase cross-react with snake venom components unrelated to the parent protein. Toxicon 2005; 46:308-17. [PMID: 16026810 DOI: 10.1016/j.toxicon.2005.04.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Accepted: 04/26/2005] [Indexed: 10/25/2022]
Abstract
It is widely accepted that immunological cross-reactivity of snake venoms is mediated by antibodies that recognize venom components bearing either amino acid sequence homology or similar biological functions. However, here we demonstrate that polyspecific Bothrops antivenom is a source of cross-reactive antibodies that interact with venom proteins of distinctive primary structures and biological functions. The homoserine lactone derivative of the undecapeptide IQRWSLDKYAM (Ile1-Hse11), excised from the l-amino acid oxidase (LAAO) of the Bothrops moojeni venom, was the ligand of an affinity resin used to isolate specific anti-Ile1-Hse11 antibodies which were instrumental in revealing immunological cross-reactivity among unrelated venom proteins. We examined the extent of the cross-reactivity of these antibodies by probing electroblots of venoms from representative snakes of genera Bothrops, Lachesis, Crotalus and Micrurus, and by unambiguous structural characterization of the affinity-purified proteins of B. moojeni venom recovered from an agarose-anti-Ile1-Hse11 column. Our results indicate that all venoms tested had at least three reactive components toward anti-Ile1-Hse11 antibodies, among which we identified two serine proteases, one phospholipase A2 homologue, and LAAO. We hypothesize that the cross-reactivity of the anti-Ile1-Hse11 antibodies to unrelated venom proteins derives from their mechanism of antigen recognition, whereby complementarity is achieved through reciprocal conformational adaptation of the reacting molecules. Also, we believe these findings have implications both in the development of improved antivenoms and the preparation of immunochemical reagents for diagnostic and scientific investigation purposes in the field of snake venoms.
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Affiliation(s)
- Rodrigo Guerino Stábeli
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina, USP, Ribeirão Preto, SP, Brazil
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Castro HC, Lemos MGJ, Bon C, Zingali RB. Comparative evaluation of immunological and structural similarities of snake venom C-type lectin proteins. Toxicon 2003; 41:525-8. [PMID: 12657323 DOI: 10.1016/s0041-0101(02)00358-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Antibodies raised against denatured and native forms of bothrojaracin were used to analyze the immunological similarities compared to the structural and biological features of five C-type lectin proteins from snake venom (bothrojaracin, botrocetin, Factor IX/X binding protein (FIX/Xbp), convulxin and Bothrops jararaca lectin). Anti-denatured-bothrojaracin antibodies, which recognize mainly linear epitopes, cross-reacted with botrocetin, FIX/Xbp and convulxin, as expected for homologous proteins. On the other hand, anti-native-bothrojaracin antibodies, which mostly interact with conformational epitopes, exhibited a higher degree of selectivity. These results show that differences exist at the surface of these proteins and that they should be related to their different biological activities, while they share a common and similar scaffold.
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Affiliation(s)
- H C Castro
- Laboratório de Hemostase e Venenos, Departamento de Bioquímica Médica, ICB/CCS, Univ. Federal do Rio de Janeiro, Bloco H, 20. andar-Ilha do Fundão Cidade Universitaria, Rio de Janeiro, RJ CEP 21941-590, Brazil
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9
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Castro HC, Fernandes M, Zingali RB. Identification of bothrojaracin-like proteins in snake venoms from Bothrops species and Lachesis muta. Toxicon 1999; 37:1403-16. [PMID: 10414865 DOI: 10.1016/s0041-0101(99)00087-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Bothrojaracin, a 27 kDa protein isolated from Bothrops jararaca venom, forms a non-covalent complex with thrombin, thus blocking its activity. We have previously identified a bothrojaracin-like protein in B. alternatus venom [Castro, H.C., Dutra, D.L.S., Oliveira-Carvalho, A.L., Zingali, R.B., 1998. Bothroalternin, an inhibitor of thrombin from the venom of Bothrops alternatus. Toxicon 36, 1903-1912]. In this report, we have examined snake venoms from six different Bothrops species (B. atrox, B. cotiara, B. jararacussu, B. moojeni and B. neuwiedi), from Lachesis muta and from Crotalus durissus terrificus for the presence of bothrojaracin-like proteins, which we define here as 27 kDa proteins that are immunologically related to bothrojaracin and that inhibit thrombin-induced platelet aggregation. The immunological analysis of these venoms by different techniques indicated the existence of at least one protein recognized by anti-bothrojaracin serum in all venoms tested. Bothrojaracin-like proteins were purified from all crude venoms, except for C. d. terrificus, by a single-step procedure using a thrombin affinity column (PPACK-thrombin-Sepharose). Retained material that inhibits thrombin-induced platelet aggregation was found in a different proportion in each species. Under non-reducing conditions, SDS-PAGE of this material revealed several bands between 20-60 kDa; only those bands corresponding to 27 kDa were recognized by anti-bothrojaracin serum. ELISA confirmed the greater bothrojaracin immunoreactivity of proteins present in B. atrox and B. cotiara as compared to other Bothrops species. Smaller amounts of proteins related to bothrojaracin were found in L. muta venom and were absent from the venom of C. d. terrificus. Our results thus suggest that bothrojaracin-like proteins are widely distributed among Bothrops genera.
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Affiliation(s)
- H C Castro
- Departamento de Bioquímica Médica, ICB/CCS, Universidade Federal do Rio de Janeiro, Brazil
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10
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Nakamura S, Nakai M, Nakashima K, Ogawa T, Shimohigashi Y, Ohno M, Kihara H, Yamane T, Ashida T. Roles of lysine-69 in dimerization and activity of Trimeresurus flavoviridis venom aspartate-49-phospholipase A2. J Mol Recognit 1996; 9:23-30. [PMID: 8723316 DOI: 10.1002/(sici)1099-1352(199601)9:1<23::aid-jmr235>3.0.co;2-p] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Trimeresurus flavoviridis (Habu snake) venom aspartate-49-phospholipase A2 (Asp-49-PLA2) was reacted at pH 9.0 with a 2-fold molar excess of 2,4,6-trinitrobenzenesulfonate in the absence of Ca2+ and two trinitrophenylated derivatives were isolated by HPLC. One was a derivative modified at Lys-11 and its activity was mostly retained. The other was a derivative modified at both Lys-11 and Lys-72 and its activity was 40% that of unmodified enzyme. Trinitrophenylation of Lys-72 appeared to bring about a conformational disorder at the lipid-water interface recognition site and thus a reduction of activity. When the enzyme was modified in the presence of Ca2+, activity decreased at a rate much faster than that in the absence of Ca2+ and Lys-69 came to be modified. These results suggested that conformational displacement of Asp-49-PLA2 of a local to global type occurs upon the binding of Ca2+. The derivative modified at Lys-69 had 28% activity and existed as a monomer. This supports a previous assumption that Lys-69 participates in dimerization of group II Asp-49-PLA2s [Brunie et al. (1985) J. Biol. Chem. 260, 9742-9749] and shows that dimerization is not necessarily essential for activity manifestation.
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Affiliation(s)
- S Nakamura
- Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan
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11
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Choumet V, Bouchier C, Délot E, Faure G, Saliou B, Bon C. Structure and function relationship of crotoxin, a heterodimeric neurotoxic phospholipase A2 from the venom of a South-American rattlesnake. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 391:197-202. [PMID: 8726057 DOI: 10.1007/978-1-4613-0361-9_12] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- V Choumet
- Unité des Venins, Institut Pasteur, Paris, France
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12
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Tsai IH, Lu PJ, Wang YM, Ho CL, Liaw LL. Molecular cloning and characterization of a neurotoxic phospholipase A2 from the venom of Taiwan habu (Trimeresurus mucrosquamatus). Biochem J 1995; 311 ( Pt 3):895-900. [PMID: 7487947 PMCID: PMC1136085 DOI: 10.1042/bj3110895] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Using gel-filtration chromatography and reverse-phase (RP) HPLC we have purified a presynaptic neurotoxin (designated as trimucrotoxin) from the crude venom of Taiwan habu (Trimeresurus mucrosquamatus). Its complete primary structure was solved by an automated N-terminal sequencing and cDNA sequencing method. The enzyme inhibited the twitch of the chick biventer cervicis muscle at 0.1-1 micrograms/ml and showed lethality in mice (LD50 = 1.2 micrograms/g, when given intravenously). Trimucrotoxin exists mainly as a homodimer of 14 kDa subunits as shown by a gel-filtration experiment, and dissociates into monomers during SDS/PAGE in the absence of Ca2+. However, most of trimucrotoxin migrated as slowly as a trimer during nondenaturing SDS/PAGE in the presence of Ca2+ or Sr2+. Its amino acid sequence identity to crotoxin B and agkistrodotoxin is about 75%, and its cDNA sequence is 82% identical to that of crotoxin B. Rabbit antiserum against trimucrotoxin also cross-reacted with the other crotalid neurotoxic phospholipases A2. Furthermore, the purified acidic subunit of crotoxin potentiated the neurotoxicity of trimucrotoxin. A comparison of the sequences of these crotalid neurotoxins revealed some common features of the possible neurotoxic sites, including residues 6, 11, 76-81 and 119-125.
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Affiliation(s)
- I H Tsai
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China
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13
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Kato T, Lee S, Oishi O, Aoyagi H, Ohno M. Interactions of N-terminal fragments of groups I and II phospholipases A2 with phospholipid bilayers and their surface recognition properties. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1211:215-20. [PMID: 8117749 DOI: 10.1016/0005-2760(94)90271-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In order to elucidate the roles of the N-terminal segments of groups I and II phospholipases A2 (PLA2s) which have been known to have alpha-helical structure and have been assumed to be involved in the water/lipid interface recognition site, the peptides corresponding to the N-terminal moieties of group I PLA2 (Naja naja atra) and group II PLA2s (Trimeresurus flavoviridis and Crotalus atrox) were synthesized and their interactions with model membranes were studied. Circular dichroism spectra showed that N-terminal peptides of both groups I and II PLA2s took alpha-helical structure in trifluoroethanol but no significant secondary structure in buffer (pH 8.0). In the presence of acidic liposomes, N-terminal fragments of group II PLA2s formed alpha-helical structure, while that of group I PLA2 remained unaffected. The hydrophobic moments showed that amphipathicities of N-terminal fragments of group II PLA2s are evidently larger than those of N-terminal fragments of group I PLA2s. The leakage of carboxyfluorescein from acidic liposomes was induced only with group II PLA2 peptides. Large blue shift and increase in intensity of tryptophan fluorescence were also observed for group II PLA2 peptides when interacting with acidic liposomes. Such difference in the modes of interactions with lipid bilayers between N-terminal peptides of groups I and II PLA2s appears to be due in large part to the difference in intrinsic alpha-helix forming properties of their amino acid sequences. It is inferred that N-terminal amphipathic alpha-helical structures of group I PLA2s are possibly formed by assistance of a neighboring chain bridged by Cys-11 and Cys-77.
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Affiliation(s)
- T Kato
- Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan
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Choumet V, Saliou B, Fideler L, Chen YC, Gubensek F, Bon C, Delot E. Snake-venom phospholipase A2 neurotoxins. Potentiation of a single-chain neurotoxin by the chaperon subunit of a two-component neurotoxin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 211:57-62. [PMID: 8425551 DOI: 10.1111/j.1432-1033.1993.tb19869.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The venoms from Crotalinae and Viperinae snakes contain only two kinds of phospholipase A2 neurotoxins (beta-neurotoxins): single-chain beta-neurotoxins, such as agkistrodotoxin and ammodytoxin-A, and dimeric beta-neurotoxins, which, in the case of the best studied ones, crotoxin-like toxins, consist of the non-covalent association of a phospholipase A2 (CB) and a non-enzymatic chaperon (CA). Possible evolutionary relationships of these beta-neurotoxins have been investigated by analyzing whether CA could behave as a chaperon toward agkistrodotoxin and ammodytoxin, as it does in the crotoxin complex. CA increased the lethal potency of agkistrodotoxin and modified its pharmacological effect on Torpedo synaptosomes. Sedimentation experiments proved that CA can form an heterocomplex with agkistrodotoxin. Agkistrodotoxin prevented the binding to CA of an anti-CA mAb which recognizes an epitope at the zone of interaction between crotoxin subunits, suggesting the association of CA and agkistrodotoxin implicated the same zone. A 10-fold molar excess of CA over ammodytoxin modified the effect of ammodytoxin on acetylcholine release but did not increase the lethal potency of ammodytoxin. Sedimentation experiments showed CA and ammodytoxin can form an heterocomplex which is less stable than CA.agkistrodotoxin. Ammodytoxin A did not compete with the anti-CA mAb. These observations are in good agreement with the sequence similarities between CB and agkistrodotoxin (80%) and ammodytoxin A (60%).
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Affiliation(s)
- V Choumet
- Unité des Venins, Unité associée Institut Pasteur, Institut National de la Santé et de la Recherche Médicale, Paris, France
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