CARBOHYDRATE-COMPOSITION OF NATIVE AND DE SIALYLATED PLASMA LOW-DENSITY LIPOPROTEINS

The monosaccharide content was examined in apoprotein B and lipids of total low density lipoprotein (LDL) preparations isolated from the blo od of healthy individuals and patients with coronary atherosclerosis, as well as in desialylated and sialylated LDL obtained by affinity chr omatography on Ricinus Communis Agglutinin-agarose. The glycoconjugate s of total apoprotein-B of healthy subjects' LDL were found to consist of N-acetylglycosamine, galactose, mannose and sialic acid in a molar ratio of 2:1:2.5:1. The content of protein-bound neutral sugars was t he same in healthy subjects and patients, while there was a lower sial ic acid amount in the patients. The level of protein-bound sialic acid in patients' desialylated LDL was 2- to 3-fold lower than that in sia lylated LDL. In contrast to apoprotein-B glycoconjugated, the lipid-bo und carbohydrate chains of total LDL preparations had N-acetylgalactos amine and glucose, but not mannose. In total LDL from patients, the co ntent of all lipid-bound carbohydrates was 1.5- to 4-fold lower than t hat in LDL from healthy subjects. In healthy subjects and in patients alike, the neutral sugar content of a lipid subfraction of desialylate d LDL was lower than in those of sialylated LDL. It is concluded that atherogenic desialylated LDL differ from non-atherogenic sialylated LD L in neutral sugar levels.