Interaction of apoprotein from porcine high-density lipoprotein with dimyristoly lecithin. 2. Nature of lipid-protein interaction.
The detailed molecular structure of the complex formed by the apoprotein from porcine high density lipoprotein and dimyristoly phosphatidylcholine (lecithin) has been investigated by a range of physical techniques. The complex, an oblate ellipsoid with major axis 11.0 nm and minor axis 5.5 nm (see the accompanying paper), is comprised of a section of lecithin bilayer with apoprotein at the surface. The main site of interaction between protein and lipid is in the lipid glycerophosphorylcholine group region; as with native high density lipoprotein the surface of the particle consists of a mosaic of lecithin polar groups and protein. The formation of this mosaic reduces the cooperativity of the lecithin chain motions and changes the curvature of the lipid-water interface, as compared to a bilayer. Otherwise, there are no major changes in lecithin motions indicating that no strong binding of lipid to protein occurs. The interaction involves the intercalation of amphipathic, 60% alpha-helical, apoprotein molecules among the lecithin molecules so that the protein residues at the lipid-water interface. The apoprotein has a high affinity for the lipid-water interface but specific lipid-protein interactions are not involved.
D000595:Amino Acid Sequence; D000818:Animals; D001059:Apoproteins / Q000097:blood; D001665:Binding Sites; D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D008075:Lipoproteins, HDL / Q000097:blood; D009682:Magnetic Resonance Spectroscopy; D008433:Mathematics; D008958:Models, Molecular; D009227:Myristic Acids; D010713:Phosphatidylcholines; D011485:Protein Binding; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D013113:Spin Labels; D013552:Swine; D013696:Temperature
D001059:Apoproteins; D008075:Lipoproteins, HDL; D009227:Myristic Acids; D010713:Phosphatidylcholines; D013113:Spin Labels