CHARACTERIZATION AND QUANTITATION OF APOLIPOPROTEIN B-100 BY CAPILLARY ELECTROPHORESIS

The interaction of low density lipoproteins (LDL) with different surfa ctants was studied by capillary electrophoresis (CE) and sucrose densi ty gradient ultracentrifugation as part of developing a method for qua ntitation of apoB-1000 in serum. A mixture of surfactants consisting o f 70% sodium dodecyl sulfate (SDS), 25% sodium myristyl sulfate, and 5 % sodium cetyl sulfate was found to delipidate LDL particles more effe ctively than pure SDS or sodium decyl sulfate. The delipidation produc ts of LDL [apolipoprotein B-100 (apoB-100) and lipids] were resolved a s two distinct peaks by CE when using a 3.5 mM 70% SDS mixture, 20% (v /v) acetonitrile, 50 mM sodium berate, pH 9.1 buffer. This CE method w as also used to characterize apoB-100 derived from samples of lipoprot ein [a] and very low density lipoproteins (VLDL). A CE-based quantitat ion method for apoB-100 was developed utilizing the observed linear re lationship between apoB-100 concentration and its corrected 214 nm abs orbance peak area measured on-line by CE. Concentration values of apoB -100 in LDL and VLDL samples were determined by CE and found to be acc urate when compared to values obtained by immunoturbidimetric analysis and the Lowry method. Capillary electrophoresis can be used as a prec ise, accurate, and specific on-line method for the qualitative and qua ntitative analysis of the apoB-100 component of VLDL and LDL-related l ipoproteins.