Inhibition of lecithin:cholesterol acyltransferase in human plasma by dicarboxylic lecithins

The effect of dicarboxylic lecithins on the lecithin:cholesterol acyltransferase [LCAT] activity was studied with a partially purified preparation [approximately 24-fold]. The presence of dicarboxylic lecithins is followed by the inhibition of LCAT. The inhibition is proportional to the concentration of glutaryl-lecithin and is about 50% with 0.16 mM glutaryl-lecithin. For a higher concentration, the inhibition is total. The inhibition of LCAT activity was of a mixed type. It can be explained by a combination of competitive inhibition and interaction of glutaryl-lecithin with phospholipid, which changes the physical properties of lipid, making it less available for conversion into cholesteryl ester.