Mechanism of Eserine Action on The Hydrolysis of Butyrylthiocholine by Butyrylcholinesterase

Abstract

The mechanism of the interaction of eserine with butyrylcholinesterase has been proposed only on the basis of analogy with acetylcholinesterase. Here the interactions was studied in detail and the results analysed by classical kinetic methods and by means of mathematical modelling. An appropriate kinetic scheme was developed, an adequate equation derived and the corresponding kinetic parameters evaluated. The findings suggest that a fast but relatively weak binding of eserine to the enzyme's active site is followed by a slow acylation step and by an even slower rate limiting deacylation step so misrepresenting eserine as an irreversible inhibitor. The proposed kinetic scheme also suggests that the reaction of eserine with a peripheral substrate site is unlikely as seen with the substrate, butyrylthiocholine.

Key Words: :

• Butyrylcholinesterase
• Eserine
• pre-steady state
• stopped-flow
• modelling.