Release of fatty acids from phosphatidylcholine by lecithin-cholesterol acyltransferase.

Partially purified lecithin-cholesterol acyltransferase [EC 2.3.1.43] from human plasma released fatty acids from phosphatidylcholine. Heating, sulfhydryl reagents, Ca2+, EDTA, and sodium deoxycholate had similar effects on the lecithin-cholesterol acyltransferase and fatty acid releasing activities of the preparation. A specific cofactor protein for lecithin-cholesterol acyltransferase, apoA-1, also enhanced both activities. Release of fatty acid was due to enzymatic hydrolysis of the ester linkage at carbon-2 of phosphatidylcholine. It is suggested that the two activities are due to a single enzyme.