Inactivation of acetylcholinesterase by propanol and sodium dodecyl sulphate.

Departure from first-order kinetics was observed for the inactivation of bovine erythrocyte and electric eel acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) by n-propanol. This was attributed to the presence of isoenzymes in the commercial preparations, although inactivation via a two-step process cannot be eliminated. The rate of inactivation of bovine erythrocyte enzyme by propanol or sodium dodecyl sulphate was decreased by the presence of added protein and increased by Triton X-100. The presence of a substrate (acetylthiocholine) decreased the rate of inactivation of bovine erythrocyte acetylcholinesterase by sodium dodecyl sulphate, but increased the rate of inactivation by propanol. Re-interpretation of earlier data on the inactivation and reversible inhibition of acetylcholinesterase by simple aliphatic alcohols indicated that they do not bind to hydrophobic regions of the active site.