Orientation and dynamics of phospholipid head groups in bilayers and membranes determined from /sup 31/P nuclear magnetic resonance chemical shielding tensors
/sup 31/P nuclear magnetic resonance (NMR) powder spectra have been used to determine the principal values of the chemical shielding tensors of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidic acid. The shielding tensors in all cases were clearly nonaxial. The principal values for the monoester phosphatidic acid shielding tensor are -40, -4, and 48 ppM relative to 85% H/sub 3/PO/sub 4/. By contrast the diesters have values of -87, -25, and 119 ppM for phosphatidylcholine, -81, -20, and 105 ppM for phosphatidylethanolamine, and -80, -20, and 112 ppM for phosphatidylserine. This difference reflects the sensitivity of the /sup 31/P shielding tensor to chemical environment. Anisotropic motion of the molecules in lamellar dispersions of phospholipids caused an incomplete averaging of the shielding tensors resulting in partially narrowed spectra. Spectra of various phospholipid dispersons were recorded as a function of temperature and transitions observed at the gel-liquid crystalline phase transition temperatures. Using a reasonable set of initial conditions, it was shown that a simple model of molecular motion could successfully predict the observed spectra and their temperature dependences. A preliminary /sup 31/P NMR spectrum of chick embryo fibroblasts is included.
- Research Organization:
- Univ. of California, Berkeley
- OSTI ID:
- 7317418
- Journal Information:
- Biochemistry; (United States), Vol. 16:3
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
FIBROBLASTS
NUCLEAR MAGNETIC RESONANCE
PHOSPHOLIPIDS
ORIENTATION
ANISOTROPY
MATHEMATICAL MODELS
ORDER PARAMETERS
PHOSPHORUS 31
PREDICTION EQUATIONS
TEMPERATURE DEPENDENCE
ANIMAL CELLS
CONNECTIVE TISSUE CELLS
EQUATIONS
ESTERS
ISOTOPES
LIGHT NUCLEI
LIPIDS
MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
RESONANCE
SOMATIC CELLS
STABLE ISOTOPES
550200* - Biochemistry
400104 - Spectral Procedures- (-1987)