Structure of human serum lipoproteins: nuclear magnetic resonance supports a micellar model.

High-resolution proton nuclear magnetic resonance spectra of low- and high-density lipoproteins from human serum closely resemble those of dispersions of lipoprotein lipids in water. Linewidths of hydrocarbon proton absorptions are not increased in the lipoproteins. In contrast, apolar binding of lysolecithin on serum albumin causes extensive line-broadening and an upfield chemical shift of the hydrocarbon proton resonances of lysolecithin. The results are consistent with a predominantly micellar structure for the lipoproteins rather than with extensive hydrophobic association of lipid and protein.