The Physical State of Lipids of Biological Importance: Cholesteryl Esters, Cholesterol, Triglyceride

Abstract

Alpha and beta serum lipoproteins and the lipids of the lesions of atherosclerosis contain a large fraction of cholesterol esters. Further, the lipid droplets of the fatty streak of the atherosclerotic lesions are probably nearly pure cholesteryl ester. Although there is a vast literature concerning the metabolism (1,2) and transport of cholesterol and its esters, very little is known of the physical state of the biologically important cholesteryl esters and even less about the physical state of these esters in mixtures of other naturally occurring lipids. Even more important, the state of these compounds in vivo has not even been studied. While it is true that pure cholesteryl esters of saturated fatty acids have been carefully examined (3–7), there has been no report of the state of monounsaturated and polyunsaturated cholesteryl esters as a function of temperature. Yet, it is these most important but neglected unsaturated and polyunsaturated esters which make up the bulk of cholesteryl esters of biologic or pathologic origin. The purpose of this report is to discuss briefly the physical state of cholesteryl esters of saturated, cis monounsaturated and cis polyunsaturated long chain fatty acids.

Markle Scholar in Academic Medicine