Membrane packing geometry of diphytanoylphosphatidylcholine is highly sensitive to hydration: phospholipid polymorphism induced by molecular rearrangement in the headgroup region.
AUTOR(ES)
Hsieh, C H
RESUMO
Diphytanoylphosphatidylcholine (DPhPC) has often been used in the study of protein-lipid interaction and membrane channel activity, because of the general belief that it has high bilayer stability, low ion leakage, and fatty acyl packing comparable to that of phospholipid bilayers in the liquid-crystalline state. In this solid-state 31P and 2H NMR study, we find that the membrane packing geometry and headgroup orientation of DPhPC are highly sensitive to the temperature studied and its water content. The phosphocholine headgroup of DPhPC starts to change its orientation at a water content as high as approximately 16 water molecules per lipid, as evidenced by hydration-dependent 2H NMR study at room temperature. In addition, a temperature-induced structural transition in the headgroup orientation is detected in the temperature range of approximately 20-60 degrees C for lipids with approximately 8-11 water molecules per DPhPC. Dehydration of the lipid by one more water molecule leads to a nonlamellar, presumably cubic, phase formation. The lipid packing becomes a hexagonal phase at approximately 6 water molecules per lipid. A phase diagram of DPhPC in the temperature range of -40 degrees C to 80 degrees C is thus constructed on the basis of NMR results. The newly observed hydration-dependent DPhPC lipid polymorphism emphasizes the importance of molecular packing in the headgroup region in modulating membrane structure and protein-induced pore formation of the DPhPC bilayer.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1180984Documentos Relacionados
- Effects of lipid headgroup and packing stress on poly(ethylene glycol)-induced phospholipid vesicle aggregation and fusion.
- Triplex hydration: nanosecond molecular dynamics simulation of the solvated triplex formed by mixed sequences
- Brain shrinkage in alcoholics is not caused by changes in hydration: a pathological study.
- Dielectric spectroscopy as a sensor of membrane headgroup mobility and hydration.
- Biomolecular hydration: From water dynamics to hydrodynamics