Intermolecular Steric Interactions and Lipid Chain Fluidity in Phospholipid Multibilayers. A Spin Label Study

1974 ◽  
Vol 52 (7) ◽  
pp. 631-636 ◽  
Author(s):  
D. Marsh
Keyword(s):  
Stearic Acid ◽  
Spin Label ◽  
Spin Labels ◽  
Energy Separation ◽  
Effective Energy ◽  
Label Study ◽  
Steric Interactions ◽  
Egg Lecithin ◽  
Lipid Chain ◽  
Ordered State

The temperature variation of the spectra of stearic acid spin labels has been investigated in oriented egg lecithin multibilayers. The temperature behavior is characterized by an effective value for the energy separation between trans and gauche conformations in the lipid chains. Comparison with bilayers containing cholesterol indicates that this effective energy is sensitive to intermolecular steric interactions. The large value for the effective gauche energy suggests that part of the lipid chains are in a relatively ordered state even in unsaturated lecithin systems.

Spin Label Study of Apomembranes and Purple Membranes

1993 ◽  
Vol 48 (5-6) ◽  
pp. 500-503
Author(s):  
Tzvetana R. Lazarova ◽  
Maya Y. Velitchkova
Keyword(s):  
Fatty Acids ◽  
Lipid Bilayer ◽  
Spin Label ◽  
Hyperfine Splitting ◽  
Esr Spectra ◽  
Spin Labels ◽  
Label Study ◽  
Splitting Parameter ◽  
Induced Changes ◽  
Purple Membranes

Abstract Three spin-labelled fatty acids were used to detect the dynamics of lipid bilayer of apomem branes and purple membranes. It was found that ESR spectra of spin labels bound to apo­ membranes showed a temperature-induced changes rather similar to those seen with purple membranes. At the same time, however, the values of hyperfine splitting parameter 2Tm were lower as compared to purple membranes. The results pointed out that the removal of the retinal from purple membranes affects the dynamics of lipid bilayer and apomembranes were more rigid structure than those of purple membranes.

A Spin Label Study of the Influence of Cholesterol on Egg Lecithin Multibilayers

1972 ◽  
Vol 50 (9) ◽  
pp. 969-981 ◽  
Author(s):  
Roy D. Lapper ◽  
Sabina J. Paterson ◽  
Ian C. P. Smith
Keyword(s):  
Electron Spin Resonance ◽  
Random Walk ◽  
Electron Spin ◽  
Spin Label ◽  
Theoretical Models ◽  
Cholesterol Content ◽  
Electron Spin Resonance Study ◽  
Spin Labels ◽  
Spin Resonance ◽  
Egg Lecithin

A detailed electron spin resonance study of a cholestane spin label in hydrated egg lecithin multibilayers of variable cholesterol content is presented. Several theoretical models are proposed in an attempt to explain the observed electron spin resonance spectra for the egg lecithin–cholesterol multibilayer system; we conclude that the most probable model is that of restricted random walk of individual spin labels where the amplitude of the random walk decreases from about 46° at 0 mol% cholesterol content to a minimum of 17° at 55 mol% cholesterol. Also, as the cholesterol content of the multibilayers increases, so the rate of random walk decreases from rapid to intermediate on the electron spin resonance time scale. The results clearly indicate that cholesterol is able to order egg lecithin films, orientating all molecules towards a normal to the surface of the film and decreasing their mobility. The condensing and stiffening influence of cholesterol in phospholipids is undoubtedly one of its major roles in biological membranes.

A spin label study of the effects of sterols on egg lecithin bilayers

1979 ◽  
Vol 23 (3) ◽  
pp. 201-211 ◽  
Author(s):  
Richard Semer ◽  
Edward Gelerinter
Keyword(s):  
Spin Label ◽  
Label Study ◽  
Egg Lecithin

A Spin Label Study of the Influence of Cholesterol on Phospholipid Multibilayer Structures

1971 ◽  
Vol 49 (5) ◽  
pp. 614-622 ◽  
Author(s):  
Jen-Chang Hsia ◽  
Henry Schneider ◽  
Ian C. P. Smith
Keyword(s):  
Simple Model ◽  
Angular Dependence ◽  
Spin Label ◽  
Rotational Frequency ◽  
Label Study ◽  
Egg Lecithin ◽  
Dipalmitoyl Lecithin ◽  
Hyperfine Splittings ◽  
Degree Of Order ◽  
Limiting Value

Cholesterol increases the degree of order indicated by the spin-labelled derivative of cholestane (3-spiro-(2′-(N-oxyl-4′,4′-dimethyloxazoIidine))-cholestane) in a hydrated multibilayer structure of egg lecithin. Estimates of the angle between the long axis of the label and the lamellar plane were obtained using a simple model for the effect of this angle on the angular dependence of the hyperfine splittings of the spin label. The deviation from perpendicularity was ~28 + 5° in the absence of cholesterol. This deviation decreased to a limiting value of ~10 ± 3° at 25 mole% cholesterol. The limiting deviation was smaller when dipalmitoyl lecithin was substituted for egg lecithin, indicating the importance of the nature of the acyl residues in this effect.The rotational frequency of the spin label about its long axis depended upon whether or not the multibilayer structure had been in contact with an aqueous phase. Before wetting, this frequency was « 75 × 106 s−1; after wetting it was » 75 × 106 s−1.

scholarly journals Organization of membrane lipids and proteins in human En(a-) erythrocytes that lack the major sialoglycoprotein, glycophorin A. A spin-label study

1981 ◽  
Vol 195 (1) ◽  
pp. 123-128 ◽  
Author(s):  
S E Jansson ◽  
J Gripenberg ◽  
R Hekali ◽  
C G Gahmberg
Keyword(s):  
Stearic Acid ◽  
Membrane Fluidity ◽  
Membrane Lipids ◽  
Spin Labels ◽  
Glycophorin A ◽  
Hydrophobic Core ◽  
Protein Motion ◽  
Normal Cells ◽  
Label Study ◽  
Spin Resonance

Membrane fluidity was studied by electron-spin-resonance techniques in human En(a-) erythrocytes that lack the major membrane sialoglycoprotein, glycophorin A. By using stearic acid spin labels with a doxyl group in the C-12 or C-15 positions, we demonstrated that the hydrophobic core in these cells was more fluid than in normal cells. Surface-located regions in isolated En(a-) membranes, when probed with stearic acid labelled in the C-5 position, appeared more stable than in normal membranes. In isolated En(a-) membranes, protein motion was decreased when probed with a nitroxide derivative of maleimide. After incubation with anti-(glycophorin A) antibodies protein motion and membrane fluidity were increased in normal membranes. This effect was observed also after spectrin depletion, which by itself increased protein motion but decreased membrane fluidity in the hydrophobic core of the membrane. The results show that membrane proteins influence the fluidity of membrane lipids.

scholarly journals A spin label study of the thyroid hormone-binding sites in human plasma thyroxine transport proteins.

1981 ◽  
Vol 256 (2) ◽  
pp. 831-836
Author(s):  
S.Y. Cheng ◽  
G. Rakhit ◽  
F. Erard ◽  
J. Robbins ◽  
C.F. Chignell
Keyword(s):  
Thyroid Hormone ◽  
Human Plasma ◽  
Spin Label ◽  
Binding Sites ◽  
Transport Proteins ◽  
Hormone Binding ◽  
Label Study

scholarly journals Spin-label study of hemoglobin conformations in solution.

1967 ◽  
Vol 58 (1) ◽  
pp. 19-26 ◽  
Author(s):  
S. Ogawa ◽  
H. M. McConnell
Keyword(s):  
Spin Label ◽  
Label Study

The Orientation of Cytochrome c Oxidase in Coupled Phospholipid Membrane Vesicles—A Spin-Label Study

1975 ◽  
Vol 53 (3) ◽  
pp. 364-370 ◽  
Author(s):  
J. A. Kornblatt ◽  
W. L. Chen ◽  
J. C. Hsia ◽  
G. R. Williams
Keyword(s):  
Molecular Weight ◽  
Binding Site ◽  
Cytochrome Oxidase ◽  
Spin Label ◽  
Resonance Spectrum ◽  
Membrane Vesicles ◽  
Phospholipid Membrane ◽  
Vesicle Membrane ◽  
Exterior Surface ◽  
Label Study

Cytochrome oxidase, an enzyme containing six different subunits, has been shown to span the inner mitochrondrial membrane. The arrangement of the subunits within the membrane is unknown. We have specifically labeled the 25 000 molecular weight subunit with a spin-label derivative of N-ethylmaleimide, 3-maleimido-2,2,5,5-tetramethyl-1-pyrrolidinyloxyl (NEM-SL(5)). NEM-SL(5)-labeled cytochrome oxidase can be incorporated into phospholipid membranes to form coupled vesicles of the Hinkle, Kim &Racker ((1972) J. Biol. Chem. 247, 1338–1339) type. The resonance spectrum of NEM-SL(5) is similar in both soluble and vesicular cytochrome oxidase. Since ascorbate has been shown to reduce only spin label that is exposed to the exterior surface of a closed vesicle, we have used ascorbate to determine the NEM-SL(5)-binding site in the coupled vesicles. NEM-SL(5)-labeled cytochrome oxidase vesicles are reduced by 10 mM ascorbate with [Formula: see text] of 1 min at 22 °C. The rate of reduction is relatively independent of temperature. We conclude that (1) cytochrome oxidase is unidirectionally or preferentially oriented in the vesicle membrane, and (2) the NEM-SL(5)-binding site on the 25 000 molecular weight subunit is exposed to the external aqueous medium.

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