title: Identification of PLA(2) and alpha-neurotoxin proteins in the venom of Pseudonaja affinis (dugite).
abstract: The Western brown snake Pseudonaja affinis (dugite), common to the Perth area of Western Australia, possesses one of the most lethal venoms in the world. Little is known, however, about the toxic protein constituents of the venom, other than those causing coagulopathic and procoagulant effects. The current study was therefore undertaken in order to identify other protein constituents and activities present. Crude venom induced a contraction in rat tracheal preparations through phospholipase A(2) (PLA(2)) activity, as shown by the complete and partial inhibition of contraction by PLA(2) inhibitors 4-bromophenacyl bromide and quinacrine. Further, a reduced degree of smooth muscle contraction in the presence of the leukotriene receptor antagonist SKF104353 suggested that this effect was mediated by leukotriene metabolites. The venom-induced contraction did not reoccur upon a second administration of the venom, despite the muscle retaining its contractile function and appearing histologically undamaged. Chromatographic separation of the protein constituents of the venom showed that PLA(2) activity was associated with all protein fractions. A low-molecular-weight component of the venom was further investigated through N-terminal sequencing and found to possess high identity to the short-chain alpha-neurotoxin family of toxins. Venom activity on cultured rat cardiac myocytes and cultured cortical neurons was also examined. The crude venom was found to temporarily inhibit the beating of the cardiac myocytes, after which the beating resumed erratically. Cortical neurons, however, were irreversibly affected, showing concentration-dependent cell death.
authors.affiliation: Department of Biochemistry, University of Western Australia, Perth, Australia.
authors.forename: Roopwant K
authors.initials: RK
authors.lastname: Judge
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Henry
authors.forename: Angela C
authors.initials: AC
authors.lastname: d'Aprile
authors.forename: Dania
authors.initials: D
authors.lastname: Lynch
authors.forename: George A
authors.initials: GA
authors.lastname: Jelinek
authors.forename: Matthew C J
authors.initials: MC
authors.lastname: Wilce
authors.forename: Jacqueline A
authors.initials: JA
authors.lastname: Wilce
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002850:Chromatography, Gel; D004546:Elapid Venoms / Q000032:analysis* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009206:Myocardium / Q000166:cytology; D009474:Neurons / Q000187:drug effects; D009498:Neurotoxins / Q000032:analysis*; D010455:Peptides / Q000032:analysis; D010741:Phospholipases A / Q000032:analysis* / Q000037:antagonists & inhibitors; D051381:Rats; D014132:Trachea / Q000187:drug effects / Q000473:pathology
chemical_list: D004546:Elapid Venoms; D004791:Enzyme Inhibitors; D009498:Neurotoxins; D010455:Peptides; D010741:Phospholipases A