Memorial University DAI: Deuterium nuclear magnetic resonance of phospholipids at high pressure

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Title	Deuterium nuclear magnetic resonance of phospholipids at high pressure
Author	Bonev, Boyan, 1966-
Description	Thesis (Ph.D.)--Memorial University of Newfoundland, 1996. Physics and Physical Oceanography
Date	1996
Pagination	xiii, 131 leaves : ill.
Subject	Phospholipids; Nuclear magnetic resonance; Deuteron magnetic resonance spectroscopy
Degree	Ph.D.
Degree Grantor	Memorial University of Newfoundland. Dept. of Physics and Physical Oceanography
Discipline	Physics and Physical Oceanography
Language	eng
Notes	Bibliography: leaves118-131
Abstract	The effect of hydrostatic pressure on saturated diacyl phospholipids was studied using deuterium NMR. A probe for deuterium NMR studies of soil materials was constructed to operate at pressures up to 2.7 kbar. The response of the bilayer to hydrostatic pressure was found to be highly anisotropic in that the bilayer thickness was observed to increase as the pressure was raised. From the temperature and pressure dependence of the first spectral moments in perdeuterated DMPC, it was concluded that the effect of temperature on area, per lipid decreased with pressure. The main transition in DMPC-d54, was analyzed in terms of a Landau-type free energy model. In another series of experiments lipid headgroups were found to tilt toward the bilayer normal, in response to a pressure-induced reduction in the area per lipid molecule in the bilayer. Experiments where temperature was varied at, high and low pressure led to the conclusion that the headgroup response to temperature consists of two effects - a hcadgroup tilt and a temperature-induced methylene disorder. In a study of perdeuterated DLPC high pressure was found to remove the overlap between the main and the subtransition and to result in the appearance of a true gel phase below the liquid crystalline phase. The low temperature end of the liquid crystalline phase was found to be dominated by an intermolecular ordering process which substantially slowed the motions. In perdeuterated DPPC, high pressure was seen to promote the formation of a number of low temperature phases. When temperature was lowered, the system was observed to pass through the liquid crystalline phase, a possibly interdigitated phase, a phase that might reflect domination by intermolecular correlations, rather than chain order, and a highly ordered crystalline phase. Cholesterol in a DPPC membrane was found to reduce the effects of hydrostatic pressure on the membrane in (lie sense that aside from the pressure-induced temperature shift the ambient pressure phase behaviour was retained even at 2.2 kbar. No evidence was found to suggest that the positioning of the cholesterol molecule in the bilayer might be affected by pressure.
Type	Text
Resource Type	Electronic thesis or dissertation
Format	Image/jpeg; Application/pdf
Source	Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Local Identifier	a1171874
Rights	The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
Collection	Electronic Theses and Dissertations
Scanning Status	Completed
PDF File	(15.03 MB) -- http://collections.mun.ca/PDFs/theses/Bonev_Boyan.pdf
CONTENTdm file name	44022.cpd