Mercuric chloride effects on the kinetic parameters of human erythrocyte membrane bound acetylcholinesterase

Kinetic analysis of the interaction of mercuric chloride with human erythrocyte acetylcholinesterase was investigated in the present study. It was found that mercuric chloride reversibly inhibited the AChE activity in a concentration dependent manner, the IC50 being 16 microM while the IC100 was 47 microM. The Km for the hydrolysis of acetylthiocholine iodide by AChE was found to be 97 microM in the control system, and the value increased by 16-144% in the mercuric chloride treated systems. The Vmax was 1.72 mumol/min/mg protein for the control as well as the mercuric chloride treated systems. Dixon as well as Lineweaver-Burke plots and their secondary replots indicated that the nature of the inhibition is of the reversible competitive type. The K(i) value was estimated as 6.26 microM. The K(i) value increased with an increase in substrate concentration.