The use of heparin-sepharose affinity chromatography to separate two distinct lipoproteins from the low density lipoprotein fraction of rat plasma.

Heparin-Sepharose affinity chromatography resolved rat lipoproteins isolated in the density range 1.019-1.063 g/ml into two distinct fractions. The first, which eluted with 150 mM NaCl, was shown by immunodiffusion and by polyacrylamide gel electrophoresis to contain predominantly apo E. On this basis the major lipoprotein present is identified as high density lipoprotein1 (HDL1). The second, eluted with 325 mM NaCl, contains predominantly apoprotein B by the same techniques. The main lipoprotein present is therefore identified as low density lipoprotein (LDL). The lipid composition of the two lipoproteins is similar. Both are rich in cholesterol ester, with a free to ester cholesterol ratio of about 1 to 2.5. From lipid and protein analyses on the two fractions, the plasma concentrations of HDL1 and LDL can be calculated to be about 14 and 12 mg/100 ml, respectively. Their mean diameters are 13 +/- 2 nm and 18 +/- 5 nm, respectively.