摘要：

Two physically separable macromolecules carry the designation apolipoproteinB. The long recognized form of apoB, large apoB or B-100, is the predominant protein in LDL and the major apoB protein found in human VLDL. This chapter describes the isolation and characterization of apolipoprotein B-100. ApoB-100 is generally an abundant apolipoprotein in plasma, and constitutes over 95% of the protein mass of low-density lipoprotein (LDL) and approximately one-third of the protein mass of very low-density lipoprotein. It is readily isolated from LDL. ApoB may be modified chemically with lysines and arginines, which changes the biological properties of the apolipoprotein. The chapter suggests that the amino acid analysis of apoB is not particularly useful in characterizing a preparation, and it has been shown that up to 30% of the protein may be removed enzymatically with little change in the amino acid composition of the remaining apoB. A minimal criterion for characterizing an apoB preparation is demonstration of a single band on a 4 or 5% SDS-polyacrylamide gel, and a second criterion is the measurement of the sedimentation coefficient.

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