Fractionation of human low density lipoprotein by column chromatography

We have devised a method to fractionate low density lipoprotein (LDL) into subspecies by means of column chromatography. DEAE-agarose columns, 2.6 X 60 cm, were loaded with LDL (25-45 mg LDL protein) and eluted with a 0.045-0.13 M NaCl gradient. The LDL eluted over a volume of 900 ml. Specific portions of the eluted LDL, reapplied to a column identical with the original, reelute at about the same point. Altering the NaCl concentration of the elution fluid changed the elution volume. The cholesterol-protein ratio of the LDL subfractions was progressively lower in fractions eluting at higher NaCl concentrations. These results indicate the LDL is not a homogenous lipoprotein species but consists of subfractions which differ in at least charge and cholesterol content.