A spin label study of purple membranes from Halobacterium halobium

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.

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

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)70053-2 ◽

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

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A Spin-Label Study on Lipids in Dough Formed at Various Concentrations of Oxygen

Agricultural and Biological Chemistry ◽

10.1080/00021369.1985.10867141 ◽

1985 ◽

Vol 49 (9) ◽

pp. 2557-2561

Author(s):

Junko Nishiyama ◽

Toyo Kuninori

Keyword(s):

Spin Label ◽

Label Study

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Spin-label study of hemoglobin conformations in solution.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.58.1.19 ◽

1967 ◽

Vol 58 (1) ◽

pp. 19-26 ◽

Cited By ~ 113

Author(s):

S. Ogawa ◽

H. M. McConnell

Keyword(s):

Spin Label ◽

Label Study

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

Canadian Journal of Biochemistry ◽

10.1139/o75-050 ◽

1975 ◽

Vol 53 (3) ◽

pp. 364-370 ◽

Cited By ~ 18

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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