Quantification of apolipoproteins B-100, B-48, and E in human triglyceride-rich lipoproteins

We have developed a procedure to quantify apolipoprotein (apo) B-100, apoB-48, and apoE in human triglyceride-rich lipoproteins. This procedure permits delipidation of small amounts of triglyceride-rich lipoproteins without appreciable losses, and quantification of these apolipoproteins in samples containing as little as 10 micrograms of protein. Delipidated triglyceride-rich lipoproteins are subjected to sodium dodecyl sulfate polyacrylamide slab gel electrophoresis, and the mass of apolipoproteins is estimated after densitometric scanning and volume integration of Coomassie blue-stained bands. The chromogenicities of apoB-100 and apoB-48 are virtually identical, and twofold lower than that of apoE. The standard curve for each apolipoprotein follows a power function over a wide protein range, permitting quantification of as little as 0.2 microgram of apoB-48 and as much as 30 micrograms of apoB-100 from a single application of triglyceride-rich lipoproteins to the gels. This method is suitable for routine use in studies of the intestinal and hepatic contributions to triglyceride-rich lipoproteins and their responses to postprandial lipemia.