Biomaterial Database

Polarity profiles in oriented and dispersed phosphatidylcholine bilayers are different: an electron spin resonance study. 1998

M Ge, and J H Freed

Baker Laboratory of Chemistry, Cornell University, Ithaca, New York 14853, USA.

A novel method was utilized to accurately measure the z- component of the nuclear hyperfine interaction tensor, Azz, of a chain-labeled lipid, 16PC, and a headgroup-labeled lipid, dipalmitoylphosphatidyl-tempocholine (DPPTC), in macroscopically oriented dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) membranes, which were compared with the Azz values of the two labels in dispersions of the same lipids in the gel phase. We found that the Azz values of 16PC (DPPTC) in the oriented DPPC and DMPC bilayers are approximately 1 Gauss smaller (greater) than in the corresponding dispersions. These results indicate that the headgroup region is more polar in macroscopically oriented bilayers than in dispersions, whereas in the chain region, the order in polarity is reversed. This is consistent with previous results on partial molar volumes in the liquid-crystal phase. Differences in the morphology of the macroscopically oriented and dispersed bilayers, which might be responsible, are discussed. Nonlinear least-squares fits of the electron spin resonance spectra of DPPTC in DPPC show that there is a substantial orienting potential in the headgroup region of dispersions that is lipid phase dependent. However, in oriented membrane samples hydrated in 100% relative humidity, this orienting potential is very weak.

UI	MeSH Term	Description	Entries
D008051	Lipid Bilayers	Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.	Bilayers, Lipid,Bilayer, Lipid,Lipid Bilayer
D008968	Molecular Conformation	The characteristic three-dimensional shape of a molecule.	Molecular Configuration,3D Molecular Structure,Configuration, Molecular,Molecular Structure, Three Dimensional,Three Dimensional Molecular Structure,3D Molecular Structures,Configurations, Molecular,Conformation, Molecular,Conformations, Molecular,Molecular Configurations,Molecular Conformations,Molecular Structure, 3D,Molecular Structures, 3D,Structure, 3D Molecular,Structures, 3D Molecular
D010713	Phosphatidylcholines	Derivatives of PHOSPHATIDIC ACIDS in which the phosphoric acid is bound in ester linkage to a CHOLINE moiety.	Choline Phosphoglycerides,Choline Glycerophospholipids,Phosphatidyl Choline,Phosphatidyl Cholines,Phosphatidylcholine,Choline, Phosphatidyl,Cholines, Phosphatidyl,Glycerophospholipids, Choline,Phosphoglycerides, Choline
D003497	Cyclic N-Oxides	Heterocyclic compounds in which an oxygen is attached to a cyclic nitrogen.	Heterocyclic N-Oxides,Cyclic N Oxides,Heterocyclic N Oxides,N Oxides, Cyclic,N-Oxides, Cyclic,N-Oxides, Heterocyclic,Oxides, Cyclic N
D004134	Dimyristoylphosphatidylcholine	A synthetic phospholipid used in liposomes and lipid bilayers for the study of biological membranes.	Dimyristoyllecithin,1,2-Dimyristoyl-glycero-3-phosphorylcholine,1,2-Ditetradecanoyl-glycero-3-phosphocholine,1,2-Ditetradecyl-glycero-3-phosphocholine,DMCP,DMPC,1,2 Dimyristoyl glycero 3 phosphorylcholine,1,2 Ditetradecanoyl glycero 3 phosphocholine,1,2 Ditetradecyl glycero 3 phosphocholine
D004578	Electron Spin Resonance Spectroscopy	A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.	ENDOR,Electron Nuclear Double Resonance,Electron Paramagnetic Resonance,Paramagnetic Resonance,Electron Spin Resonance,Paramagnetic Resonance, Electron,Resonance, Electron Paramagnetic,Resonance, Electron Spin,Resonance, Paramagnetic
D013113	Spin Labels	Molecules which contain an atom or a group of atoms exhibiting an unpaired electron spin that can be detected by electron spin resonance spectroscopy and can be bonded to another molecule. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)	Spin Label,Label, Spin,Labels, Spin
D015060	1,2-Dipalmitoylphosphatidylcholine	Synthetic phospholipid used in liposomes and lipid bilayers to study biological membranes. It is also a major constituent of PULMONARY SURFACTANTS.	Dipalmitoyllecithin,1,2-Dihexadecyl-sn-Glycerophosphocholine,1,2-Dipalmitoyl-Glycerophosphocholine,Dipalmitoyl Phosphatidylcholine,Dipalmitoylglycerophosphocholine,Dipalmitoylphosphatidylcholine,1,2 Dihexadecyl sn Glycerophosphocholine,1,2 Dipalmitoyl Glycerophosphocholine,1,2 Dipalmitoylphosphatidylcholine,Phosphatidylcholine, Dipalmitoyl
D015394	Molecular Structure	The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.	Structure, Molecular,Molecular Structures,Structures, Molecular