Systematic analysis of serum lipoproteins and apolipoproteins by a combined technique of micro two‐dimensional electrophoresis

Abstract

Abstract Lipoproteins in human serum and in lipoprotein fractions obtained by sequential ultracentrifugation of serum were analyzed by combining three types of micro two‐dimensional electrophoresis (2‐DE) technique to obtain systematic information on lipoproteins and apolipoproteins. The samples were first analyzed under non‐denaturing conditions of electrophoresis to characterize the physicochemical properties of low‐density lipoproteins (LDL) and high‐density lipoproteins (HDL) under physiological conditions. The samples were then analyzed, employing isoelectric focusing without denaturants in the first dimension and sodium dodecyl sulfate (SDS) electrophoresis in the second dimension, to study the process of dissociation of lipoproteins to apolipoproteins. The HDL's dissociated into their constituent apolipoproteins, showing that the charge heterogeneity of HDL is caused by the heterogeneous apolipoprotein content. LDL dissociated into apo B‐100 and minor components. In the third type of micro 2‐DE, employing urea and Nonidet P‐40 in the first dimension and SDS in the second dimension, the lipoproteins were dissociated into their apolipoproteins during the steps of sample treatment, to obtain the information on the contnt of apolipoprotein peptides and their genetic alleles. The combined micro 2‐DE technique will be useful for the systematic analysis of lipoproteins and apolipoproteins in hypo‐ and hyperlipoproteinemic patients.