[Structural analysis of lethal snake venom neurotoxins by change transfer]

Among the two Trp and the unique Tyr present in the amino-acid sequence of the neurotoxin of Naja naja philippinensis, only one Trp is reactive in intermolecular charge transfer experiments, using organic electron acceptors. In the reference toxin-alpha of Naja nigricollis, neither the single Trp nor the Tyr, both invariant and essential for lethality, are available for charge transfer. A minor and very weak complex is obtained, which is assumed to be initiated by an exposed His. Although fully exposed, the additional Trp of the former toxin, adjacent to invariant Trp-28, fails to influence lethality and binding to the cholinergic receptor.