EFFECT OF SEVIN ON KINETIC-PARAMETERS OF CAMEL RETINA ACETYLCHOLINESTERASE

The present investigation addresses the effect of sevin (insecticide) on kinetic parameters of camel retina membrane-bound acetylcholinester ase (AChE, EC 3.1.1.7). The Michaelis-Menten constant (K-s) for the hy drolysis of acetylthiocholine iodide (ASCh) by AChE was 0.072 mM in th e control system, a value decreased by 38-55% in the sevin treated sys tems. The V-max was 0.967 mu mole/min/mg protein for the control syste m while it was decreased by 50-84% in the sevin treated systems. The L ineweaver-Burk plot, Dixon plot, and their secondary replots indicated that the nature of the inhibition was of the linear mixed type, i.e. uncompetitive and noncompetitive. The values of K-i(slope) and K-l(int ercept) were estimated as 6.194 and 2.811 mu M, respectively. The turn over number (K-cat) and specificity constant (K-sp) were 74.65 min(-1) and 10.37 x 10(5)(M. min)(-1) in the control system respectively, whi le the values for both parameters were significantly decreased in the sevin treated systems.