CHARACTERIZATION AND QUANTITATION OF THE APOPROTEINS OF HIGH-DENSITY-LIPOPROTEIN BY CAPILLARY ELECTROPHORESIS

A method has been developed using capillary electrophoresis (CE) to qu antitate plasma levels of apoprotein A-I (apoA-I) and apoprotein A-II (apoA-II) in high density lipoprotein (HDL) samples. ApoA-I and apoA-I I are resolved by CE in delipidated and non-delipidated HDL samples. C oncentrations of apoA-I and apoA-II were calculated from their peak ar eas in the electropherogram. Results of the analysis of Sigma plasma s tandards (Controls 1 and 2) using CE are in good agreement with values obtained by Sigma using immunoturbidimetric assay. CE and reverse-pha se high-performance liquid chromatography (RP-HPLC) were found to be c omplementary in the study of apoA-I and apoA-II. RP-HPLC resolves the isoforms of purified apoA-I and apoA-II, but it cannot resolve mixture s of them because the retention times of the isoforms overlap. CE sepa rates apoA-I from apoA-II, but it does not resolve the isoforms. Matri x-assisted laser desorption/ionization mass spectrometry was used to i dentify the isoforms of apoA-I and apoA-II by their molecular weight ( M(r)) in fractions collected from RP-HPLC. (C) 1996 Academic Press, In c.