Some mechanisms of transverse nuclear magnetic relaxation in model membranes
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Sternin, Edward
issued: 2010-10-21T19:06:51Z
issued: 1988
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Experimental proof is presented that some of the motions responsible for transverse relaxation (T₂) in deuterium magnetic resonance (²H NMR) experiments on acyl chains of a model membrane in the liquid crystalline phase are extremely slow on the ²H NMR time scale being characterized by a correlation time T₂ > ѡq⁻¹. The experiments used to investigate these slow motions involve a form of the Carr-Purcell-Meiboom-Gill pulse sequence modified so as to be suitable for ²H NMR (q-CPMG). The most plausible mechanism responsible for T₂ relaxation is the gradual change in the average molecular orientation due to lateral diffusion of the phospholipid molecules along curved membrane surfaces. Presence of such diffusion is directly established by a selective inversion recovery experiment in which magnetization transfer across the spectrum is seen. The results of the T₂ relaxation as measured in the q-CPMG experiments are fitted to an average correlation time, T₂ ≈ 62 ms, yielding an estimate of the average effective radius of curvature of 1.2 µm for a typical model membrane system, in good agreement with other methods of measurement. The implications of this main result are examined for a number of model membranes; in particular, considerable changes are seen in the character of molecular motions in systems containing small concentrations of sterols. Similarly, changes caused by the topological differences between the lamellar L∝ and hexagonal H₁₁ phases are examined in a model membrane system which undergoes a L∝ to H₁₁ phase transition. A novel way of quantifying the differences in the orientational order parameters across the phase transition is used; the observed differences are consistent with the different symmetry properties of the two phases. Perdeuteriated polycrystalline hexamethylbenzene is used to demonstrate various methods of measuring ²H NMR relaxation. In addition, some aspects of orientation dependence of the relaxation rates are examined, and found to agree wi…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/29432
note: S O M E M E C H A N I S M S O F T R A N S V E R S E N U C L E A R M A G N E T I C R E L A X A T I O N I N M O D E L M E M B R A N E S Edward Sternin B. Sc. (Mathematics and Physics) University of British Columbia M. Sc. (Physics) University of British Columbia A THESIS SUBMITTED IN THE REQUIREMENTS DOCTOR OF PARTIAL FULFILLMENT OF FOR THE DEGREE OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF PHYSICS We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA August 1988 @ Edward Sternin In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for refer-ence and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Physics The University of British Columbia 1956 Main Mall Vancouver, Canada Date: Abstract Experimental proof is presented that some of the motions responsible for transverse relaxation ( T2) in deuterium magnetic resonance ( 2 H NMR) experiments on acyl chains of a model membrane in the liquid crystalline phase are extremely slow on the 2 H NMR time scale being characterized by a correlation time Ti > u;" 1 . The experiments used to investigate these slow motions involve a form of the Carr-Purcell-Meiboom-Gill pulse sequence modified so as to be suitable for 2 H NMR (q-CPMG). The most plausible mechanism responsible for T-i relaxation is the gradual change in the average molecular orientation due to lateral diffusion of the phospholipid molecules along curved membrane surfaces. Presence of such diffusion is directly established by a selective inversion recovery experiment in which magnetization transfer across the …
has type: Thesis/Dissertation
is shown at: 10.14288/1.0085008
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/29432