Phosphatidylcholine substrate specificity of lecithin:cholesterol acyltransferase.

Lecithin:cholesterol acyltransferase (LCAT) has been partially purified by the combined method of ultracentrifugation and dextranblue-2000 4 B affinity chromatography. The enzyme was incubated with liposomes consisting of phosphatidylcholine-cholesterol in a molar ratio of 10/1. Chemically synthesized phosphatidylcholine substrates with labeled fatty acids in 1-and 2-position were chosen to evaluate the degree of transesterification. It was found that the fatty acid in the 1-position of phosphatidylcholine significantly influences cholesteryl ester formation, both by its direct involvement in the LCAT reaction and its contribution to the physico-chemical properties of phosphatidylcholine.