Structure and dynamics of alpha-tocopherol in model membranes and in solution: a broad-line and high-resolution NMR study

Journal Article · Mon Mar 07 23:00:00 EST 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00405a007· OSTI ID:7070128

Ekiel, I H; Hughes, L; Burton, G W; Jovall, P A; Ingold, K U; Smith, I C

Nuclear magnetic resonance has been applied to study the conformational dynamics of alpha-tocopherol (vitamin E) in solution and in model membranes. In nonviscous solution, /sup 1/H nuclear magnetic resonance (NMR) showed that alpha-tocopherol is in rapid equilibrium between two or more puckered conformers of its heterocyclic ring. The most likely conformers to be so involved are the two half-chair forms. Deuterium NMR spectra of specifically deuteriated alpha-tocopherol in multilamellar dispersions of egg phosphatidylcholine, measured in the liquid-crystalline state, were characteristic of axially symmetric motional averaging. The orientation of the rotational axis within the molecular framework was determined. Studies on oriented multilamellar membranes revealed that this axis is perpendicular to the surface of the membrane. The profile of quadrupolar splittings along the hydrophobic tail does not have a plateau, in contrast to that of the fatty acyl chains of the membrane lipids. Longitudinal relaxation times (T1) were short. The presence of a minimum in their temperature dependence shows that molecular motion with an effective correlation time tau eff approximately equal to 3 X 10(-9)s is responsible for relaxation. However, the temperatures and absolute values of the minima depend on the position of the deuterium in the molecule, demonstrating that tau eff represents a complex blend of motions.

• Research Organization: National Research Council of Canada, Ottawa, Ontario
• OSTI ID: 7070128
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:5; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
DEUTERIUM
DISPERSIONS
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MIXTURES
MOLECULAR STRUCTURE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-ODD NUCLEI
RESONANCE
SOLUTIONS
SPECTRA
STABLE ISOTOPES
TRACER TECHNIQUES
VITAMIN E
VITAMINS