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Nuclear magnetic relaxation studies of lecithin bilayers

Citation

Feigenson, Gerald W. (1974) Nuclear magnetic relaxation studies of lecithin bilayers. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-10142005-110429

Abstract

In an effort to elucidate the state of molecular motion in aqueous lecithin systems, the nuclear magnetic relaxation properties of unsonicated lecithin crystal and liquid crystal phases have been investigated. The presence of a narrow component in the nmr spectrum of aqueous lamellar lecithin crystals is taken to indicate a significant degree of motion of the lecithin methyl groups in this solid phase. Also in the crystal state of lecithin, nmr linewidth measurements, together with thermal analysis experiments appear to indicate that a structural rearrangement of either the lecithin or the bound water takes place, which is not accompanied by an increase in molecular mobility. Delayed Fourier Transform and wide-line nmr experiments show that at the crystal -> liquid crystal (bilayer) phase transition temperature, the lecithin choline methyl, terminal methyl, and hydrocarbon chain methylene protons are all simultaneously mobilized. A previously noted field dependence of the proton magnetic resonance linewidth of aqueous lecithin bilayers is shown to be accounted for by the chemical shift differences among the various kinds of protons. Spin lattice relaxation rates have been measured for these protons as a function of temperature and frequency, and these data have been interpreted in terms of models for the segmental motion of the choline head groups and the hydrocarbon chains. The influence of spin diffusion on the relaxation behavior of the various protons is also discussed.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Chan, Sunney I.
Thesis Committee:
  • Unknown, Unknown
Defense Date:26 November 1973
Record Number:CaltechETD:etd-10142005-110429
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-10142005-110429
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:4084
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:14 Oct 2005
Last Modified:26 Dec 2012 03:05

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