A 2H solid-state NMR spectroscopic investigation of biomimetic bicelles containing cholesterol and polyunsaturated phosphatidylcholine

Abstract

Deuterium solid-state NMR spectroscopy was used to qualitatively study the effects of both 1-palmitoyl-2-linoleoyl- sn-glycero-3-phosphatidylcholine (PLiPC) and cholesterol on magnetically aligned phospholipid bilayers (bicelles) as a function of temperature utilizing the chain-perdeuterated probe 1,2-dimyristoyl- sn-glycero-3-phosphatidylcholine (DMPC- d 54) in DMPC/dihexanoylPC (DHPC) phospholipid bilayers. The results demonstrate that polyunsaturated PC and cholesterol were successfully incorporated into DMPC/DHPC phospholipid bilayers, leading to a bicelle that will be useful for investigations of eukaryotic membrane protein–lipid interactions. The data indicate that polyunsaturated PC increases membrane fluidity and decreases the minimum magnetic alignment temperature for DMPC/DHPC bicelles. Conversely, the introduction of cholesterol into aligned DMPC/DHPC bilayers decreases fluidity in the membrane and increases the minimum temperature necessary to magnetically align the phospholipid bilayers. Finally, the addition of Tm 3+ to magnetically aligned DMPC/DMPC- d 54/PLiPC/DHPC bilayers doubles the quadrupolar splittings, indicating that this unique bicelle system can be aligned with the bilayer normal parallel to the static magnetic field.