A method for incorporating labeled lacithin into serum low density lipoproteins in vitro

A sonicated dispersion of [14C]lecithin was incubated with high density lipoproteins (HDL) coupled to Sepharose. After washing the gels thoroughly with a buffer, the gels were incubated with low density lipoproteins (LDL); [14C]lecithin was transferred from the sonicated dispersion via HDL-Sepharose to the LDL. The LDL fraction thus prepared showed no contamination with lecithin dispersion or HDL. The lecithin:cholesterol acyltransferase (LCAT) reaction could be completely inhibited during preparation, and the net recovery of radioactivity in LDL was 16% of that of the original lecithin dispersion. The [14C]lecithin in the washed HDL-Sepharose was shown to be a substrate of the LCAT reaction in vitro.