Solution, semisolid, and solid NMR studies of lipid model membranes.
Item
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Title
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Solution, semisolid, and solid NMR studies of lipid model membranes.
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Identifier
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AAI9707077
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identifier
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9707077
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Creator
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Chen, Zhenjia.
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Contributor
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Adviser: Ruth E. Stark
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Date
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1996
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Organic | Chemistry, Biochemistry
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Abstract
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Using a combination of 1D and 2D solution NMR, it is possible to assign all of the {dollar}\sp1{dollar}H resonances for two complex C{dollar}\sb8{dollar}-based model digestive mixtures. Our new structural model based on two dimensional nuclear Overhauser effect spectroscopy (NOESY) and rotating-frame NOE spectroscopy (ROESY) describes the molecular organization of monoglyceride (MG), fatty acid (FA), and bile salt (BS) constituents. This proposal accounts for a large body of new NMR data, including Mn{dollar}\sp{lcub}2+{rcub}{dollar} titrations and NOE connectivities.;Magic angle spinning (MAS) assisted semisolid NMR was used to observe two distinct water resonances for N-monomethyldioleoylphosphatidylethanolamine (MeDOPE) bilayers in the liquid-crystalline phase. The downfield shifted peak with the shorter T{dollar}\sb1{dollar} relaxation time was ascribed to hydrogen-bonded interlamellar water in slow exchange with other water molecules. The upfield peak with a long T{dollar}\sb1{dollar} relaxation time arises from an exchange averaging between the bulk water and lipid solvation water. The hydrogen-bonded water also showed intense cross-peaks in the 2D magic angle spinning assisted NOESY spectrum with the lipid headgroup. In a second initiative, we used several deuterated DMPCs to systematically investigate the origin of the NOESY crosspeak between methyl groups of the lipid headgroup and the acyl chains. We have proposed a new mechanism for formation of these types of crosspeaks, which is through-space interactions between the headgroup and backbone protons and spin diffusion along the acyl chains. Thirdly, a series of MAS {dollar}\sp1{dollar}H and {dollar}\sp{13}{dollar}C NMR experiments were carried out for multilamellar dispersions formed by phosphatidylcholine (PC)/cholesterol (CH) and sphingomyelin (SPM)/cholesterol (CH), which lay the groundwork for systematic studies of packing and organization in model membranes with varying constituents and compositions.;Finally, solid-state {dollar}\sp{13}{dollar}C and {dollar}\sp2{dollar}H NMR spectroscopy was used to study the molecular structure and dynamic properties of lime and tomato cuticles. Controlled hydrolysis of the lime cutin polyester was carried out in order to elucidate its molecular architecture; the insoluble residues were analyzed with CPMAS {dollar}\sp{13}{dollar}C NMR. To examine how hydration alters the dynamic properties of both tomato cuticle and absorbed D{dollar}\sb2{dollar}O, {dollar}\sp2{dollar}H NMR investigations were conducted in parallel.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
