Quantitation of apoB-48 and apoB-100 by gel scanning or radio-iodination

In this presentation, we have validated two procedures for the separation and quantitation of apoB-48 and apoB-100 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE): 1) gamma counting of radio-iodinated lipoproteins and 2) scanning of stained gels. Total apoB in SDS solutions was determined by absorbance at 220 nm, and validated by amino acid analysis. The absorbance at 220 nm, in contrast to the Lowry procedure, could be used with BSA as a standard without correction factors. At relative apoB-48 concentrations higher than 10% of total apoB, both scanning and radio-iodination gave reliable results. At lower relative apoB-48 concentrations, the radio-iodine method appeared to be superior, but at low total apoB concentrations, the efficiency of radio-iodination was low.