Incorporation of cholesterol into serum high and low density lipoproteins.

Excess cholesterol (CHL) was incorporated into serum lipoproteins by incubation with Celite-dispersed CHL or CHL crystals. The initial rates of uptake were 15 and 7 mol CHL/ mol lipoprotein X h-1 for low (LDL) and high (HDL) density lipoprotein, respectively. Saturation values were obtained after 48 h and were 90 and 65 mol CHL/mol LDL, and 42 and 32 mol/mol HDL using CHL on Celite and CHL crystals, respectively. Characterization of the lipoproteins showed a small change in electrophoretic mobility and an increase in molecular masses, especially after incubation with CHL on Celite. Spectroscopic methods showed only minor effects on the protein moieties.