Composition, concentration, and size of low density lipoproteins and of subfractions of very low density lipoproteins from serum of normal @entity1 and XXXX .

@entity1 @entity1674 @entity755 @entity412 @entity8557 @entity165
Low density lipoprotein (LDL) and four subfractions, A, B, C, and D of very low density lipoprotein (VLDL), characterized by the following decreasing Sf values, greater than 400, 175-400, 100-175, and 20-100, respectively, were isolated by density gradient preparative ultracentrifugation from serum of normal @entity1 and @entity1 and analyzed for lipids, total protein, and @entity755 . The percentage distribution of the @entity1674 of VLDL on fractions A to D were 1, 25, 30, and 45%, respectively, for both males and females. The numbers of VLDL particles for males in fractions B to D were 5, 10, and 40 X 10(12) per ml serum, respectively. Females, who had lower VLDL concentrations than males, had half as many particles per ml of serum. The number of LDL particles was similar in males and females and was 10 times that of VLDL. The relative composition of the lipoproteins changed progressively from fraction B to D and from D to LDL. The percentage of @entity412 and soluble proteins fell, due to loss of mass of these constituents from the particles. The percentage of @entity755 and @entity8557 rose; this was not due to an increase of mass but because the particles became smaller. There were no sex differences. The numbers of molecules per particle of the constituents showed a successive decrease from VLDL-B to LDL for @entity1674 , free @entity165 , phospholipids, and soluble apolipoproteins, while it remained constant for @entity755 , as well as for @entity8557 from VLDL-C to LDL. These data fit the following hypothesis for the VLDL to LDL cascade. The large VLDL particle successively loses molecules of @entity1674 (core) and of soluble protein, free @entity165 , and phospholipids (surface). In this process, VLDL retains its molecules of @entity755 , and @entity8557 are lost from large VLDL but not from medium or small-sized VLDL.
