Immunochemical characterization of alpha-bungarotoxin detoxified with glutaraldehyde

Modification of alpha-bungarotoxin (alpha-BuTX) with glutaraldehyde (GA), a bifunctional reagent, resulted in the formation of crosslinked derivatives. The intramolecular linked monomeric derivative as well as dimeric and higher molecular weight derivatives arising from intermolecular reactions were separated by gel filtration. The dimer and polymers were completely detoxified and the monomer lost nearly all of its lethal toxicity as well as binding activity to the nicotinic acetylcholine receptor. However, all the modified derivatives retained relatively high antigenic activity towards the antibody against native toxin. Antisera prepared by immunization with the unfractionated modified products of alpha-BuTX contained considerable amounts of a non-precipitating antibody, but much less of a precipitating antibody to alpha-BuTX, while they had the same capacity as that of anti-alpha-BuTX for neutralizing the lethal toxicity of alpha-BuTX. Furthermore, the antisera could be obtained in only half period required for anti-alpha-BuTX sera so that the detoxified GA-alpha-BuTX is an useful immunogen for the production of antibody to alpha-BuTX.