NMR studies of peptide, protein and mixed-lipid systems.
Item
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Title
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NMR studies of peptide, protein and mixed-lipid systems.
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Identifier
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AAI9304696
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identifier
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9304696
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Creator
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Longo, Paula Alissa.
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Contributor
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Advisers: Ruth E. Stark | Michelle S. Broido
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Date
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1992
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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, Physical | Chemistry, Biochemistry
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Abstract
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High resolution solution-state and magic-angle spinning NMR spectroscopy have been used to structurally characterize several different types of biological polymers. The amino-terminal fragment of the p21 protein and three analogues (two oncogenic and one not) were found, using two-dimensional NOE spectroscopy, to undergo rapid conformational averaging and to contain no long-lived identifiable structures.;An 11 kD digestive enzyme, porcine pancreatic colipase, was found to exist as a dimer at concentrations suitable for two-dimensional NMR analysis. While this fact precluded a complete conformational study, a possible long-range hydrophobic-hydrophobic dipolar interaction was observed which suggests a foldover of the protein. This foldover has been postulated to bring the two binding sites on the protein close together. Additionally, the results of this study underscore the need for protein size determination using a non-denaturing method. This should be done prior to NMR investigations and at millimolar protein concentrations.;Several model mixtures, representative of the late-stage products of trigylceride digestion, have been analyzed using solution-state and MAS NMR. All mixtures contained a fatty acid (either C8 caprylic or C18 oleic acid), a monoglyceride (either C8 monocapryoyl-rac-glyercol or C18 monooleoyl-rac-glycerol) and the bile salt taurocholate. C8 mixtures were found, using solution-state NMR spectroscopy, to form mostly mixed micelles. NOESY and ROESY data demonstrate that the BS sidechain has a dual function and location within the aggregate. Additional evidence for a structure accommodating these conditions came from Mn{dollar}\sp{lcub}2+{rcub}{dollar} titration experiments.;C18 mixtures, which partition into two layers were found to form large aggregates. For C18 top layers, MAS NMR spinning sidebands indicated that the acyl chains are highly ordered. Additional spinning sidebands indicated the presence of surprisingly ordered solvent molecules. These data suggest a bilayer-vesicle aggregate for both C18 top layers. The C18 bottom layers were found to contain either BS monomers or mixed micelles, which were similar to, but larger than, the ones found for C8.
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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.
