Cholesterol and apoprotein quantitation in lipoproteins

Lipids are solubilized and transported by associating with carrier proteins (apoproteins) to form lipoproteins. Their physical and chemical properties allow separation, quantification and characterization by both the lipid and protein portions of these macromolecules. Separation and quantitation methods based on the lipid-protein content include ultracentrifugation, electrophoresis and precipitation. Measurements of LDL cholesterol and HDL cholesterol and the associated methodological variations and errors are discussed. As the physiological roles of apoproteins are elucidated, their quantitative values, determined by immunochemical methods, can be used for describing and diagnosing disorders of lipoprotein metabolism.