EVIDENCE FOR DISTINCT BEHAVIOR OF PHOSPHATIDYLCHOLINE AND SPHINGOMYELIN AT THE LOW-DENSITY-LIPOPROTEIN SURFACE

This study demonstrates that the use of high field H-1 NMR spectroscop y permits individual detection of phosphatidylcholine and sphingomyeli n molecules at the surface of native low density lipoprotein (LDL) par ticles. Distinct behaviour was observed for the choline head group -N( CH3)(3) resonances of these different phospholipids revealing preferen tial immobilisation for phosphatidylcholine. This suggests the existen ce of reversible and irreversible phosphatidylcholine-apolipoprotein B interactions and is consistent with microdomain formation at the surf ace monolayer of LDL. The novel resonance assignment and results show that H-1 NMR can provide efficient and practical means for future stud ies on the structure and dynamics at the LDL surface. (C) 1997 Academi c Press.