Interaction between botulinum neurotoxin type A and ganglioside: Ganglioside inactivates the neurotoxin and quenches its tryptophan fluorescence

This study found that ganglioside quenched the tryptophan fluorescence of botulinum neurotoxin type A (BoNT A.), accompanied by the inactivation of the toxin under low ionic strength conditions. This finding suggests that the ganglioside-binding site of BoNT A contains tryptophan residues. The quantum yield (a conformation parameter) in BoNT A under high ionic strength conditions differed from that under low ionic strength. This observation indicates that high ionic strength may alter the conformation of BoNT A, resulting in failure of the interaction between BoNT A and ganglioside. (C) 1997 Elsevier Science Ltd.