Identification of multiple subclasses of plasma low density lipoproteins in normal humans.

Density gradient ultracentrifugation of low density lipoproteins (LDL) from 12 normal subjects showed multiple, distinct isopycnic bands.Densitometric scanning of the gradient tubes revealed that each band could be assigned to one of four density intervals and that the boundaries of these intervals were consistent among all the subjects.Analytic ultracentrifuge flo- tation (Sp) rates were assigned to the four density intervals, and there was a strong correlation between peak Sp rate and ' Burke, D.