Neutron scattering study of human serum low density lipoprotein

Regions of different proton density in the low density lipoprotein (LDL) particle from human serum have been determined by neutron scattering. From measurements in various H2O/D2O mixtures, the LDL particle appears to be quasi-spherical, with the centers of gravity of the hydrocarbon and polar regions coinciding. The average volume occupied by a particle was found to be 3.2 X 10-6 A-3, with the volume fraction occupied by the hydrocarbons being 60%. The ratius of gyration of the hydrocarbon region was 64 A, while that of the polar region was 100 A. consequently, the core of LDL is predominantly occupied by the hydrocarbon chains, while the outer shell is sparsely occupied by protein emerging from the lipid core.