title: Phospholipid-protein interactions in human low density lipoprotein detected by 31P nuclear magnetic resonance.
abstract: 31P nuclear magnetic resonance (NMR) spectra of human low density lipoprotein (LDL) has been obtained and the major phospholipid components identified. Analysis of the spectra revealed two phospholipid environments: one occupied by 4/5 of the phospholipid with high resolution resonances possessing properties similar to phospholipids in vesicles, and a second occupied by 1/5 of the phospholipid with broad lines indicative of immobilization. Limited trypsin treatment of the particle cleaved all of the B peptide into smaller molecular weight peptides which remained with the particle. Trypsin-treated LDL eluted from a Sepharose CL-6B column similarly to native LDL so that the modified particle remained intact. 31P NMR spectra of trypsin-treated LDL showed little or no immobilized phospholipid. The immobilization in the native LDL particle is attributed to lipid-protein interactions between 1/5 of the phospholipid and the B peptide.
mesh_terms: D001053:Apolipoproteins / Q000097:blood; D006801:Humans; D007122:Immunoelectrophoresis; D008077:Lipoproteins, LDL / Q000097:blood; D009682:Magnetic Resonance Spectroscopy; D010446:Peptide Fragments / Q000032:analysis; D010743:Phospholipids / Q000097:blood; D011485:Protein Binding; D011487:Protein Conformation; D014357:Trypsin
chemical_list: D001053:Apolipoproteins; D008077:Lipoproteins, LDL; D010446:Peptide Fragments; D010743:Phospholipids; D014357:Trypsin