OPTIMIZATION AND KINETIC-STUDIES OF HUMAN ERYTHROCYTE MEMBRANE-BOUND ACETYLCHOLINESTERASE

The human erythrocyte membrane-bound acetylcholinesterase was characte rized with respect to optimal assay conditions for its kinetic propert ies. It was found that 40.0 mu g protein and 5.0 min incubation time w ere the suitable concentration of AChE protein and reaction time for t he linearity of AChE activity at 25 degrees C. The V-max for the AChE was 35% higher in the presence of 25 mM sodium phosphate buffer than 2 5 mM Tris-HCl buffer. The AChE activity was assayed at various strengt hs of sodium phosphate buffer (0.0125-0.20M), and the optimum strength was found to be 0.05M. The optimum substrate (ASCh) concentration was found to be 5.0 mM whereas at higher substrate concentrations, the AC hE activity declined. The ASCh concentration ranges for different orde rs of the reactions were determined and kinetic parameters (K-m, V-max , k(cat) and k(sp)) were established at each order of the reaction.