Order and fluidity in the terminal methyl region of dipalmitoyl phosphatidylcholine multibilayers: a comparison of Raman and 2H-NMR spectroscopy. 1982

R Mendelsohn, and R Dluhy, and W Curatolo, and B Sears

Deuterium magnetic resonance (2H-NMR) and Raman spectroscopy are used to investigate order and fluidity at the terminal methyl position in 16-d3, 16'-d3 dipalmitoylphosphatidyl-choline (16-d6 DPPC) multibilayers. These methods reveal substantial motion and disorder in the gel phase, 5-10 degree C below the gel-liquid crystal phase transition temperature (Tm). The phase transition is sensed in the 2H-NMR spectrum as a reduction in the quadrupole splitting from 14 kHz to approximately 3 kHz. In contrast, the Raman parameter used to characterize the CD3 vibrations is quite insensitive to the melting process, although an analagous parameter does sense disordering at Tm at the 10 and 10' position in 10-d2, 10'-d2 DPPC. The difference in the response of the NMR and Raman parameters may arise because the vibrational spectrum of the CD3 group is inhomogeneously broadened and is therefore quite sensitive to alterations in the local environment around the methyl group. In contrast, the NMR quadrupole splitting is sensitive to both local motion of the methyl group and, near Tm, to motions of the CD2 group induced by transgauche isomerizations further up the chain. The difficulties that arise when results from different spectroscopic techniques are compared are demonstrated.

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
D008560 Membrane Fluidity The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature. Bilayer Fluidity,Bilayer Fluidities,Fluidities, Bilayer,Fluidities, Membrane,Fluidity, Bilayer,Fluidity, Membrane,Membrane Fluidities
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
D009682 Magnetic Resonance Spectroscopy Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING). In Vivo NMR Spectroscopy,MR Spectroscopy,Magnetic Resonance,NMR Spectroscopy,NMR Spectroscopy, In Vivo,Nuclear Magnetic Resonance,Spectroscopy, Magnetic Resonance,Spectroscopy, NMR,Spectroscopy, Nuclear Magnetic Resonance,Magnetic Resonance Spectroscopies,Magnetic Resonance, Nuclear,NMR Spectroscopies,Resonance Spectroscopy, Magnetic,Resonance, Magnetic,Resonance, Nuclear Magnetic,Spectroscopies, NMR,Spectroscopy, MR
D011663 Pulmonary Surfactants Substances and drugs that lower the SURFACE TENSION of the mucoid layer lining the PULMONARY ALVEOLI. Surfactants, Pulmonary,Pulmonary Surfactant,Surfactant, Pulmonary
D013059 Spectrum Analysis, Raman Analysis of the intensity of Raman scattering of monochromatic light as a function of frequency of the scattered light. Raman Spectroscopy,Analysis, Raman Spectrum,Raman Optical Activity Spectroscopy,Raman Scattering,Raman Spectrum Analysis,Scattering, Raman,Spectroscopy, Raman
D013696 Temperature The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms. Temperatures

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