title: Isolation and characterization of rufoxin, a novel protein exhibiting neurotoxicity from venom of the psammophiine, Rhamphiophis oxyrhynchus (Rufous beaked snake).
abstract: Colubrid snake venoms potentially represent a vast source of novel biological actives and structural motifs owing to their diverse phylogeny. The present study describes the identification of rufoxin, a neurotoxin from the venom of Rhamphiophis oxyrhynchus (Rufous beaked snake) which is a member of the African colubrid lineage, the psammophiines. Rufoxin (1 microM) displayed reversible post-synaptic neurotoxic activity as evidenced by significant inhibition of indirect twitches and responses to exogenous nicotinic agonists in the chick biventer cervicis nerve-muscle preparation. Rufoxin (0.1-1.0 microM) also caused a rightward parallel shift of cumulative concentration-response curves to carbachol (CCh; 0.6-80 microM) without a significant depression of the maximum response, suggestive of classical competitive antagonism at the skeletal muscle nicotinic receptor. Rufoxin lacks NH(2)-terminal sequence homology to previously identified snake venom toxins. This work indicates a wider distribution of neurotoxins across the advanced snake superfamily than previously described.
authors.affiliation: Institute for Molecular Bioscience, University of Queensland, St Lucia, Qld 4072, Australia.
authors.forename: Natalie G
authors.initials: NG
authors.lastname: Lumsden
authors.forename: Yajnavalka
authors.initials: Y
authors.lastname: Banerjee
authors.forename: R Manjunatha
authors.initials: RM
authors.lastname: Kini
authors.forename: Sanjaya
authors.initials: S
authors.lastname: Kuruppu
authors.forename: Wayne C
authors.initials: WC
authors.lastname: Hodgson
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002645:Chickens; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D017812:Colubridae; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009388:Neostigmine / Q000494:pharmacology; D009469:Neuromuscular Junction / Q000187:drug effects*; D009498:Neurotoxins / Q000302:isolation & purification* / Q000494:pharmacology*; D012910:Snake Venoms / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013997:Time Factors
chemical_list: D002800:Cholinesterase Inhibitors; D009498:Neurotoxins; D012910:Snake Venoms; D009388:Neostigmine