title: Lethal toxins and cross-neutralization of venoms from the African water cobras, Boulengerina annulata annulata and Boulengerina christyi.
abstract: Venoms of the water cobras, Boulengerina, were assayed for lethality, proteolytic activity and protein content. Boulengerina annulata annulata and B. christyi venoms averaged 89% protein and lacked proteolytic activity. The murine i.p. LD50 of B. a. annulata and B. christyi venoms were 0.143 and 0.120 mg/kg, respectively. Polyvalent antivenom produced by the South African Institute of Medical Research neutralized 575 and 200 LD50 of B. a. annulata and B. christyi venoms/ml antivenom, respectively. Cation exchange chromatography resolved four lethal peaks from B. a. annulata venom and six lethal peaks from B. christyi venom. The major lethal peaks (about 12% of total venom protein) were purified further with molecular sieve chromatography and were characterized as 61 (B. a. annulata toxin) and 62 (B. christyi toxin) residue polypeptides with four half-cystines. Elucidation of the complete amino acid sequences indicated that these toxins belonged to the short-chain class of postsynaptic neurotoxins. Short-chain neurotoxins 1 from B. a. annulata and B. christyi had murine i.p. LD50 of 0.052 and 0.083 mg/kg, respectively, and showed over 80% homology with N. nigricollis alpha toxin. Reverse-phase analysis of another peak present in both venoms resolved a toxin that had an N-terminus identical to B. christyi short-chain neurotoxin 1. These fractions also contained toxins readily separable from the short-chain isotoxin by preparative reverse-phase chromatography. Amino acid sequencing of the first 28 residues indicated that both toxins were long-chain neurotoxins with identical N-termini. The LD50 of long-chain neurotoxins 2 from B. a. annulata and B. christyi venoms were 0.086 and 0.090 mg/kg, respectively. The venoms of these little-known elapids have the lowest LD50 of any African proteroglyph studied thus far and have high concentrations of potent postsynaptic neurotoxins.
authors.affiliation: Pathophysiology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702-5011.
authors.forename: S A
authors.initials: SA
authors.lastname: Weinstein
authors.forename: J J
authors.initials: JJ
authors.lastname: Schmidt
authors.forename: L A
authors.initials: LA
authors.lastname: Smith
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000997:Antivenins / Q000276:immunology; D018680:Cholinergic Antagonists; D002852:Chromatography, Ion Exchange; D002853:Chromatography, Liquid; D003429:Cross Reactions; D004546:Elapid Venoms / Q000201:enzymology / Q000276:immunology / Q000633:toxicity*; D010450:Endopeptidases / Q000032:analysis; D005779:Immunodiffusion; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D011506:Proteins / Q000032:analysis; D013045:Species Specificity
chemical_list: D000997:Antivenins; D018680:Cholinergic Antagonists; D004546:Elapid Venoms; D011506:Proteins; D010450:Endopeptidases