Carbon-13 magic angle spinning NMR studies of myelin membranes
Husted Altenberg, Cynthia
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https://hdl.handle.net/2142/22978
Description
Title
Carbon-13 magic angle spinning NMR studies of myelin membranes
Author(s)
Husted Altenberg, Cynthia
Issue Date
1991
Doctoral Committee Chair(s)
Oldfield, Eric
Department of Study
Biology, Neuroscience
Chemistry, Physical
Biophysics, Medical
Discipline
Biology, Neuroscience
Chemistry, Physical
Biophysics, Medical
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Neuroscience
Chemistry, Physical
Biophysics, Medical
Language
eng
Abstract
"We have obtained high-field (11.7 T), high-resolution $\sp{13}$C solid state ""magic angle"" sample spinning nuclear magnetic resonance (MAS NMR) spectra of a variety of model phospholipids, sphingolipids, myelin and white matter samples, resolving and assigning over 60 resonances in the spectra of human myelin samples. Spectra of fresh bovine white matter, and subsequent myelin and lipid extract preparations, revealed essentially no changes due to sample preparation, sample freezing, or brain location. Microtome stains and light microscopy, electron microscopy, thin layer chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis studies confirmed sample viability before and after NMR data acquisition. Human myelin and white matter chemical shift assignments were initially based on individual model lipid spectra and spectra of lipid mixtures assembled to simulate myelin lipid composition. Assignments were confirmed by using spectral simulations. Quantitative analysis of model lipid mixtures were within 10% of known lipid compositions and were thus used to estimate the phospholipid, sphingolipid and cholesterol mole ratios in myelin and white matter. Relative changes in phospholipids, sphingolipids, and cholesterol as well as fatty acid chain compositions were observed in developmental studies of human myelin, as well as in an abnormal development leukodystrophy, and in multiple sclerosis. Lipid motion in model and myelin membranes was probed by means of variable temperature $\sp{13}$C NMR in the range 37$\sp\circ$C to $-$105$\sp\circ$C, carbon-detected $\sp1$H T$\sb{1 \sb\rho}$, and linewidth studies. Differential mobility was observed as the lipid backbone and cholesterol ring resonances ""froze out"" before those of the fatty acyl chain, and mobile cholesterol side chain. Correlation time estimates are reported for the various lipid molecular sites of myelin, based on linebroadenings observed in proton-decoupled spectra. Variable temperature spectra of various ichthyological myelins were obtained, noting myelin lipid changes with growth temperature adaptation. Preliminary proton MAS drug-membrane data of local anesthetics, utilizing two-dimensional cross-correlation (NOESY) experiments, is presented. Finally, structural elucidation of one component of a Chinese medicinal plant is presented, using several two-dimensional NMR techniques."
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