Failure to inhibit in vitro or in vivo acetycholinesterase with botulinum toxin type A.

An attempt has been made to replicate an earlier finding that type A botulinum toxin can inhibit the in vitro activity of acetylcholinesterase. Two methods of enzyme assay were employed, but with neither technique were we able to reproduce the finding of in vitro enzyme inhibition. In fact, an examination of the data from the previous report leads us to question the possibility of the observations that were given. Furthermore, an investigation was carried out to determine if botulinum toxin can exert an inhibiting effect on acetylcholinesterase that is situated in the biological tissue. The answer again is negative. The experimental observations, coupled with several mathematical computations, do not support the notion that botulinum toxin is an acetylcholinesterase inhibitor.