Density and composition models for lipoproteins

Two theoretical models for lipoprotein particle structure are proposed, based on density and composition and utilizing the Stokes' coefficient as evaluated from the Maude-Whitemore expression, using analytical ultracentrifugation. These density and composition models are compared with the Corey-Pauling-Koltun space-filling model proposed by Verdery and Nichols, and that proposed by Shen et al., which has a sharply defined boundary between the hydrophobic core and the amphipathic layer surrounding it. Results of our calculation of the percentage of total apolar lipid accommodated in the outer hydrophobic core -28, 64 and 94% for LDL, HDL2 and HDL3, respectively - suggest that there may be differences among these three lipoproteins classes in both the packing of cholesteryl ester and triglyceride as well as the conformation of apolipoproteins at the particle's surface.