Structure-Function Relationship of Hydrophiidae Postsynaptic Neurotoxins
Mid-term rept. 1 Mar 1989-31 Aug 1990
COLORADO STATE UNIV FORT COLLINS DEPT OF BIOCHEMISTRY
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Lapemis toxin, from sea snake venom Lapemis hardwickii, binds tightly and specifically to the nicotinic acetylcholine receptor AChR inhibiting neuromuscular transmission and results in muscular paralysis. Although many neurotoxins have been isolated from snake venoms, their exact mode of binding to the AChR is still unclear. Use of Lapemis toxin has an advantage for structure-functions studies because the exact amino acid sequence is known. Chemical modification study of which of the three arginines are involved in the neurotoxin-AChR demonstrated that Arg-31 and Arg-34 residues are involved in toxin-AChR interaction. Synthetic peptides duplicating the loop domains of this toxin were made. Results of toxicity check indicated all of the synthesized peptides are non-toxic at the high dosage used 120 x Ld50 of Lapemis toxin. The binding studies for these peptides with the AChR are underway. The results will further the structure-function information about the toxin-receptor interaction. The peptides may also serve as antagonists or antigens for raising antibodies that will neutralize the neurotoxin effects in vivo.