Effects of cholesterol on lateral diffusion and vertical fluctuations in lipid bilayers. An electron-electron double resonance (ELDOR) study

Journal Article · Mon Nov 30 23:00:00 EST 1987 · Biophys. J.; (United States)

DOI:https://doi.org/10.1016/S0006-3495(87)83296-4· OSTI ID:5445997

Yin, J J; Feix, J B; Hyde, J S

Electron-electron double resonance (ELDOR) and saturation-recovery spectroscopy employing /sup 14/N:/sup 15/N stearic acid spin-label pairs have been used to study the effects of cholesterol on lateral diffusion and vertical fluctuations in lipid bilayers. The /sup 14/N:/sup 15/N continuous wave electron-electron double resonance (CW ELDOR) theory has been developed using rate equations based on the relaxation model. The collision frequency between /sup 14/N-16 doxyl stearate and /sup 15/N-16 doxyl stearate, WHex (16:16), is indicative of lateral diffusion of the spin probes, while the collision frequency between /sup 14/N-16 doxyl stearate and /sup 15/N-5 doxyl stearate, WHex (16:5), provides information on vertical fluctuations of the /sup 14/N-16 doxyl stearate spin probe toward the membrane surface. Our results show that: (a) cholesterol decreases the electron spin-lattice relaxation time Tle of /sup 14/N-16 doxyl stearate spin label in dimyristoylphosphatidylcholine (DMPC) and egg yolk phosphatidylcholine (egg PC). (b) Cholesterol increases the biomolecular collision frequency WHex (16:16) and decreases WHex (16:5), suggesting that incorporation of cholesterol significantly orders the part of the bilayer that it occupies and disorders the interior region of the bilayer. (c) Alkyl chain unsaturation of the host lipid moderates the effect of cholesterol on both vertical fluctuations and lateral diffusion of /sup 14/N-16 doxyl stearate. And (d), there are marked differences in the effects of cholesterol on lateral diffusion and vertical fluctuations between 0-30 mol% and 30-50 mol% of cholesterol that suggest an inhomogeneous distribution of cholesterol in the membrane.

• Research Organization: National Biomedical ESR Center, Milwaukee, WI (USA)
• OSTI ID: 5445997
• Journal Information: Biophys. J.; (United States), Journal Name: Biophys. J.; (United States) Vol. 52:6; ISSN BIOJA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOLOGICAL EFFECTS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHOLESTEROL
DIFFUSION
ELECTRON SPIN RESONANCE
HYDROXY COMPOUNDS
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MEMBRANES
MONOCARBOXYLIC ACIDS
NITROGEN 14
NITROGEN 15
NITROGEN ISOTOPES
NUCLEI
OCTADECANOIC ACID
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
RESONANCE
STABLE ISOTOPES
STEROIDS
STEROLS