Orientational order of cholesteryl oleate in low-density lipoprotein observed by 2H-NMR.

Cholesteryl oleate, selectively deuterated at various positions along the acyl chain, has been incorporated into fresh human serum low-density lipoprotein (LDL2). Temperature-dependent 2H-NMR spectra were recorded between 15 and 45 degrees C. For deuterons at C-2' and C-5' of the acyl chain, two 2H-NMR spectral components, a broad and a narrow signal, are observed.

Apocytochrome c binding to negatively charged lipid dispersions studied by spin-label electron spin resonance.

The interaction of apocytochrome c with aqueous dispersions of phosphatidylserine from bovine spinal cord and with other negatively charged phospholipids has been studied as a function of pH and salt concentration by using spin-label electron spin resonance (ESR) spectroscopy and chemical binding assays. The ESR spectra of phospholipids spin-labeled at different positions on the sn-2 chain indicate a generalized decrease in mobility of the lipids, while the characteristic flexibility gradient toward the terminal methyl end of the chain is maintained, on binding of apocytochrome c to phosphatidylserine dispersions. This perturbation of the bulk lipid mobility or ordering is considerably greater than that observed on binding of cytochrome c.

Deuterium NMR study of the interaction of alpha-tocopherol with a phospholipid model membrane.

The effects of 5, 10, and 20 mol % incorporation of alpha-tocopherol (vitamin E) on 50 wt % aqueous multilamellar dispersions of sn-2-substituted [2H31]palmitoylphosphatidylcholine (PC-d31), a saturated, deuterated phospholipid prepared from egg lysophosphatidylcholine, have been studied by deuterium nuclear magnetic resonance (2H NMR) and differential scanning calorimetry (DSC). Moment analysis of the 2H NMR spectra as a function of temperature and DSC heating curves demonstrate that the main gel to liquid-crystalline phase transition is progressively broadened and its onset temperature lowered by increasing concentrations of alpha-tocopherol. Below the transition temperature (40 degrees C) for PC-d31 bilayers, the 2H NMR spectra indicate that acyl chain motion is increased by addition of alpha-tocopherol and that this effect extends to lower temperatures with higher alpha-tocopherol content.

Deuterium NMR study of the effect of n-alkanol anesthetics on a model membrane system.

The effects of 25 mol% incorporation of two anesthetics, 1-octanol and 1-decanol, on a deuterated, saturated phospholipid in 50 wt% aqueous multilamellar dispersions have been studied by 2H-NMR spectroscopy and differential scanning calorimetry (DSC). The phospholipid used is sn-2 substituted '[2H31]-palmitoylphosphatidylcholine' (PC-d31). DSC thermograms demonstrate that PC-d31 has phase behavior qualitatively similar to that of dipalmitoylphosphatidylcholine, with a pretransition at 31 degrees C and a main gel to liquid crystalline transition at 40 degrees C.

Chain dynamics of selectively deuterated fatty acids in high-density lipoproteins studied by deuterium NMR.

Deuterium order parameters have been determined for approximately 5 mol% selectively deuterated palmitic acid incorporated into the outer monolayer of high-density lipoproteins (HDL3). The values are SCD = 0.38 for [2,2-2H2]palmitic acid, 0.