new, simple and economical approach to analyze the inhibition kinetics of acetylcholinesterase using tolserine

ABSTRACT

Tolserine is a novel and highly selective synthetic inhibitor of the enzyme acetylcholinesterase [AchE] that is being developed towards clinical trials for the treatment of Alzheimer's disease. We recently characterized its enzyme kinetics for inhibiting purified human erythrocyte AChE by utilizing classical methodology. In the current study, we describe a new approach to analyze its mechanism of inhibition of AChE. This was undertaken with purified human erythrocyte AChE using low to higher substrate concentrations in both the absence and presence of dual tolserine concentrations. The optical density of the generated reaction-product then was monitored during the initial reaction time after addition of each concentration of substrate. Thereafter, the new kinetic parameters [Kneidc, Kesic, Kslxx, Krss, Kslm and Kslx] were calculated from the resulting experimental data. These kinetic constants will hopefully aid our understanding of the mechanism of inhibittion and kinetic analysis of a variety of critical physiological enzymes by a wide assortment of inhibitors in vitro, during health, aging and disease. A low Kneidc value of 2.31 nM for tolserine indicates that it is a highly potent inhibitor of human erythrocyte AChE, which supports previous reports of its unusually high potency for inhibiting AChE both in vitro and in vivo, as compared to its structural analogues, physostigmine and phenserine