Raman spectra of some snake venom components.

The Raman spectra of aqueous solutions of cobrotoxin, erabutoxin b (short-chain neurotoxins), alpha-bungarotoxin (a long-chain neurotoxin), cardiotoxin, cytotoxin I (cardiotoxins), 6-carboxyl-modified cobrotoxin and cobrotoxin treated with 5 M guanidine-HCl (denatured neurotoxins) were investigated. The main-chain structure of the toxins was found to consist predominantly of beta-pleated sheets and random-coils. The relative amounts of the beta-conformations were estimated to be in order of: cardiotoxins approximately short-chain neurotoxins greater than long-chain neurotoxins greater than Laticauda semifasciata III (exceptionally weak neurotoxin). Most of the disulfide-bridges of every toxin take the gauche-gauche structure about the CC-SS-CC linkage. However, the number of gauche-gauche structures is not the same among the neurotoxins. Tyr-25 of cobrotoxin is found to form a strong hydrogen bond similar to that of other short-chain neurotoxins investigated earlier.