Lipid Arrangements on the Lipid Layer of Human Serum Lipoproteins

Abstract

The lipid arrangements on the lipid layer (as biomembrane model) of molecular surface of human serum low density and high density lipoproteins (LDL and HDL) were examined using the immunological techniques. Antiserum against etiocholenic acid which mainly reacted with the ring A of cholesterol, anti-cholesterol suc-cinate antiserum which mainly reacted with the side chain of cholesterol and antiserum against phosphatidic acid which reacted to the polar portion of phospholipids were obtained. We prepared also the sheep red cells sensitized with etiocholenic acid, cholesterol succinate and phosphatidic acid. Passive haemagglutination inhibition reaction using LDL and HDL as inhibitors was carried out. LDL reacted with the cholesterol succinate system and with the phosphatidic acid system, and HDL reacted with the etiocholenic acid system and with the phosphatidic acid system. These results suggest that the side chain of cholesterol directed to the outside of LDL molecule and the ring A of cholesterol directed toward the surface of HDL molecule. And the polar portion of phospholipids was on the surface of LDL and HDL molecules.