Separation of two serum very low density lipoprotein fractions using starch block electrophoresis

A quantitative electrophoretic method has been developed in order to differentiate very low density (VLDL) pre-beta lipoproteins from late pre-beta lipoproteins using starch as a supporting medium. It was possible to obtain a bimodal distribution of lipoprotein lipids from VLDL which on agarose gel electrophoresis had a pre-beta band and a late pre-beta band. Optimal conditions were: ammonium carbonate buffer, mu = 0.025, dialysis prior to electrophoresis. Agarose gel electrophoresis demonstrated that the fast and slow components obtained on starch block electrophoresis corresponded to the pre-beta and late pre-beta band respectively. With increasing migration towards the anode the ratio of cholesterol to triglycerides decreased continuously. It is suggested that the fast triglyceride rich component represent newly secreted VLDL species and the slower component mainly postlipolytic particles. The pre-beta band on agarose gel electrophoresis might represent more newly secreted VLDL than the late pre-beta band. However, it cannot be excluded that part of late pre-beta lipoproteins may be secreted de novo.