Studies on cholesterol esterification in human tissues.

In vitro cholesteryl synthesis from oleic acid [1-14C] was studied with enzyme preparations from human thoracic aorta and liver. Results from studies on the properties of the esterifying system provide good evidence that the mechanism involves fatty acyl-CoA-cholesterol acyl transferase. In studies on human thoracic aorta with varying degrees of atherosclerotic disease, and pairs of normal and diseased aorta from the same subject, there was no obvious relationship between aortic cholesteryl esterifying activity and severity of atheroma. Normal aorta from two young males, presumably free of atherosclerosis, had relatively very low esterifying activity. In the six liver samples tested, there was negligible esterifying activity, in contrast to the high activity seen in the case of rat liver. For the thin layer chromatographic isolation of the labeled cholesteryl oleate a solvent system of isooctane:diethyl ether (100:6) was found to give a better separation of the ester than the petroleum ether: diethylether:acetic acid system generally used.