Isolation and Characterization of Plasma Lipoproteins and Apolipoproteins
The plasma lipoproteins are the major carriers of lipid in the circulation. Structurally, these particles represent a microemulsion of triglyceride and cholesteryl ester stabilized by a polar surface of phospholipid, cholesterol, and protein (Bradley and Gotto, 1978; Morrisett et al., 1977). Four major classes of plasma lipoproteins have been designated on the basis of their ultracentrifugal flotation properties in salt solutions. These are the chylomicrons, very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). Chylomicrons and VLDL float at d < 1.006 g/ml. The LDL are isolated between d = 1.02 and 1.063 g/ml, and HDL between d = 1.063 to 1.210 g/ml. Although the classification based on ultracentrifugation in salt solutions has proven to be a useful nomenclature, each of these density ranges actually contains a complex mixture of lipoproteins of varying protein and lipid composition. The physical and chemical properties of human plasma lipoproteins are summarized in Table I. Chylomicrons and VLDL contain primarily triglycerides as their neutral lipid, whereas LDL and HDL are the major carriers of cholesteryl esters and phospholipids.
KeywordsPlasma Lipoprotein Standard Buffer Solubilization Buffer Anhydrous Diethyl Ether Void Peak
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