| Abstract: | Very high density lipoproteins d : 1.23--1.25 g/ml (VHDL2) have been isolated from human serum by preparative ultracentrifugation. They contain 80 per cent proteins and 20 per cent lipids. Lipids are mainly phospholipids (80 per cent). The proportion of lysolecithin (50 per cent) is higher than that of lecithin (40 per cent). The quantity of cholesterol is low, the free cholesterol: total cholesterol ratio is 0.35. VHDL2 consisted principally in lipoprotein D and two lipoproteins immunologically apparented to apolipoprotein A I, called LP A I1 and LP A I2. The LP A I1 has a molecular weight slightly higher and a hydrated density lower than that of LP AI2. Our experiments suggest that LP A I1 exists in the serum before ultracentrifugation while LP A I 2 comes from HDL degradation during ultracentrifugation. The immunological heterogeneity of apo A I forming different protein-lipid complexes is discussed. |
