ANALYSIS OF LOW-DENSITY LIPOPROTEINS BY PREPARATIVE ULTRACENTRIFUGATION AND REFRACTOMETRY

A simplified method for the analysis of both the glyceride-rich Sf 20-105 and the cholesterol-rich Sf 0-20 low-density lipoproteins is presented. It consists of serum lipoprotein fractionation by preparative ultracentrifugation and subsequent quantitative analysis by refractometry. Comparison of this technique with the technically more difficult analytic ultracentrifugal methodology reveals comparable results for these two principal low-density lipoprotein groups. The relationships between these lipoproteins and the serum levels of total lipids, glycerides, total cholesterol, and phospholipids are also presented. One of the advantages of this procedure is that it provides a reliable and reproducible means for quantifying the principal glyceride-bearing lipoprotein group–the Sf 20-105 lipoproteins.