Structural studies of both uniformly 13C labeled and natural abundance lipid/water systems were initiated with Magic-Angle Spinning NMR at 400 MHz. In particular, solution state 1H-13C coherence transfer schemes were employed in conjunction with MAS to obtain novel high resolution 1H-13C chemical correlation spectra of fluid phase lipids. These experiments were extended to 600 MHz with an obvious gain in resolution as well as sensitivity. The experiments included 2D-13C-1H-HSQC and 3D HCCH correlation spectra. We plan to extend these techniques to the measurement of long range 13C-1H J couplings in uniformly labeled galactolipids. Interglycosidic J couplings along with 13C-1H and 13C-13C dipolar couplings obtained via more traditional solid state NMR techniques will enable us to investigate details of lipid head group structure. In addition, the higher resolution obtained at 600 MHz is also particularly useful when studying lipid-lipid and lipid-water interactions in DLPC/POPS mixtures, where spectral crowding is a major problem. These studies allow one to have a more accurate picture of magnetization pathways and spin diffusion in model membranes, as well as some information on lipid domain sizes. Finally, a synthetic peptide, gramicidin A, was introduced in the membrane and an ambitious project has been initiated with the attempt to obtain structural information on the peptide at physiological temperature.
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