Effect of organophosphate pesticides on lecithin-cholesterol acyltransferase in human plasma

Abstract Organophosphates—dimethyldichlorovinylphosphate (DDVP), methylparathion and sumithion—inhibited the esterification of cholesterol in sonicated dispersions of lecithin-cholesterol mixtures by the lecithin-cholesterol acyltransferase in human plasma. The order of inhibition by these compounds on the esterification was DDVP > methylparathion > sumithion. This difference in degree of inhibition by DDVP, methylparathion and sumithion was not due to differences in enzymatic degradation of these compounds during incubation. The inhibitory effect of Organophosphates on the acyltransferase was not eliminated by the addition of albumin, tri-serine, poly-serine and sulfhydryl protection agents. Poly-serine was a potent inhibitor of the acyltransferase.