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|Title:||A Deuterium Nuclear Magnetic Resonance Study of Phospholipid and Glycosphingolipid Headgroup Structure|
|Author(s):||Skarjune, Robert Paul|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The results of nuclear magnetic resonance (NMR) experiments with various phospholipids and glycosphingolipids are used to derive structural and motional information about these molecules within lipid bilayers. Reasonable models of motion are inferred from various experimental results, and calculated NMR parameters are determined for all molecular orientations within desired conformational spaces. These calculated results are compared with the experimental results to determine which conformations are possible solutions to the headgroup structure.
For the phospholipids, calculations are performed for dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylethanolamine, and these same lipids in the presence of cholesterol. Conformation spaces near the previously determined X-ray structures are examined for consistency with the experimental spectra. In all cases, large numbers of conformational solutions are found, although these can be separated into a few "quasi-conformations" if torsion angle ranges are used instead of specific angular values.
For the glycosphingolipids, deuterium NMR experiments were done with N-palmitoylgalactosylceramide(PGAC) and N-palmitoylglucosylceramide (PGLC) deuterated in the fatty acid sidechain (PGAC) or in the headgroup (PGLC). The headgroup labeled PGLC spectra are used to perform an orientational analysis of the glucose headgroup similar to that done with choline. The final results demonstrate that there are two well-defined carbohydrate ring orientations consistent with the NMR spectra and the assumed motional model. Furthermore, it is shown that additional experiments with deuterium labels at different positions should permit an unambiguous description of the ring orientation for dispersions of pure PGLC as well as dispersions in which the cerebroside is only one of the lipid components.
The theory upon which the analysis is based is presented as well as the computer programs used to perform the actual calculations. In addition, supplementary work done in collaboration with other laboratories using neutron diffraction, differential scanning calorimetry, and low-temperature NMR is described.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
|Date Available in IDEALS:||2014-12-13|