Rotational diffusion of bacteriorhodopsin in lipid membranes

Cherry, Richard J.; Müller, Ulrike; Schneider, Gyula

doi:10.1016/0014-5793(77)80498-5

Cited by 68 publications

(32 citation statements)

References 23 publications

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“…Otherwise the analysis of the decay of anisotropy (e.g., fig.5) follows that in [4,6] developed for the special case where 8, = e2 and J/ = 0. Finally, it can be noted that the phosphorescence lifetime, quantum yield, and sensitivity to quenchers are all environmentally sensitive, and as a by-product may provide information on changes in the conformation or associations of the membrane protein under study.…”

Section: Discussionmentioning

confidence: 65%

“…So far measurements of rotational relaxation times have been limited to those proteins which are present at high occupancy either in the orginal membrane, as with the band-3 proteins of erythrocyte ghosts [2], or in highly purified fragments of membrane such as the acetylcholine receptor protein of the electric organ of Torpedo mamorata [3], or in reconstituted membranes [4]. This restriction arises from the relative insensitivity of the two measurement methods usually used, either saturation transfer EPR spectroscopy [5] or the decay of linear dichroism following flash photolysis of an attached triplet-forming probe such as eosin [6].…”

Section: Introductionmentioning

confidence: 99%

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Phosphorescence depolarization and the measurement of rotational motion of proteins in membranes

1979

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Section: Discussionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Phosphorescence depolarization and the measurement of rotational motion of proteins in membranes

1979

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“…It would be surprising if the same rapid rotation of the whole protein were to be maintained under conditions where there is little or no bulk lipid bilayer. Model system studies in fact confirm that protein rotation slows considerably at low lipid/protein ratios (Cherry et al, 1977).…”

Section: Discussionmentioning

confidence: 88%

Rotation motion and flexibility of calcium(2+),magnesium(2+)-dependent adenosine 5'-triphosphatase in sarcoplasmic reticulum membranes

Buerkli¹,

Cherry²

1981

Biochemistry

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Ca2+,Mg2+-dependent adenosine 5'-triphosphatase (ATPase) in sarcoplasmic reticulum vesicles is labeled with the triplet probe, 5-iodoacetamidoesin. Rotational mobility of the ATPase is investigated by measuring flash-induced transient dichroism of the eosin probe. The absorption anisotropy measured 20 mus after the exciting flash is found to be small at 37 degrees C but increases considerably with decreasing temperature and upon fixation with glutaraldehyde. A purified Ca2+,Mg2+-dependent ATPase preparation partially depleted of membrane lipids exhibits similar properties. The low value of the anisotropy at 37 degrees C is due to the existence of a fast motion which in part is assigned to independent segmental motion of the protein. This internal flexibility of the ATPase may have considerable significance for the functional properties of the enzyme. At times longer than 20 mus, the anisotropy decays with a time constant which varies from approximately 90 mus at 0 degrees C to approximately 40 mus at 37 degrees C. This decay is assigned to rotation of the ATPase about an axis normal to the plane of the membrane. There is some evidence for self-aggregation of the protein at lower temperatures.

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“…Membranes made from a single lipid species (19,20), from two or more lipids (21,22), and from both lipids and peptides (23)(24)(25)(26)(27)(28) (31)(32)(33) fulfills all the requirements listed above. Moreover, reasonably accurate rotational diffusion coefficients for BR in these vesicles have recently been obtained (33).…”

mentioning

confidence: 99%

Lateral and rotational diffusion of bacteriorhodopsin in lipid bilayers: experimental test of the Saffman-Delbrück equations.

Peters¹,

Cherry²

1982

Proc. Natl. Acad. Sci. U.S.A.

290

232

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Lateral diffusion of bacteriorhodopsin and a lipid analogue has been measured in dimyristoylphosphatidylcholine bilayers as a function of temperature, phospholipid/protein (mol/mol; L/P) ratio, and aqueous phase viscosity. The protein lateral diffusion coefficients measured above the temperature at which the lipid gel-liquid/crystalline phase transition occurs (Tc) are combined with previously determined rotational diffusion coefficients to provide a test of the Saffman-Delbrfick equations [Saffman, P. G. & Delbrfick, M. (1975) Procm NatL Acade Sci USA 72,[3111][3112][3113]. Insertion of the diffusion coefficients into these equations enables the protein diameter to be calculated. The value of 4.3 ± 0.5 nm so obtained is in reasonable agreement with the known structure of bacteriorhodopsin. A 12-fold increase in the viscosity of the aqueous phase reduces protein lateral diffusion coefficients by 50%, which is also consistent with the Saffman-Delbruick equations. Both protein and lipid lateral diffusion coefficients decrease with decreasing L/P ratio above the T,. It is argued that, at a high L/P ratio, this effect is probably due to changes in membrane viscosity while, at a low L/P ratio, "crowding" effects (steric restrictions) and protein aggregation become important. When comparing diffusion measurements made in different systems, it is important to take the effect of the L/P ratio into account. When this is done, other published measurements offreely diffusing membrane proteins are in good agreement with the present results and the predictions of the Saffman-Delbruick equations. Below the Ta, the presence of protein enhances diffusion rates. The overall effect is to smooth out the large change in diffusion coefficient that occurs at the T,.It is probable that diffusion plays a crucial role in a number of membrane functions [e.g., receptor-mediated processes (1), electron transfer (2), and photoreception (3)]. Much has been learned about this field by the use of optical techniques developed for measuring diffusion of membrane components (for review, see refs. 4-6). Fluorescence microphotolysis (7) is a versatile means for measuring translational and rotational diffusion in single cells, isolated membranes, artificial membranes, and solution (8-13). Transient dichroism of intrinsic chromophores or triplet probes has provided data on the rotational diffusion of a variety of membrane proteins (14). In the case of triplet probes, rotational diffusion has also been measured by using phosphorescence (15,16), delayed fluorescence (17), and fluorescence-depletion signals (18).A fruitful approach for analyzing parameters that potentially might restrict and regulate mobility in cellular membranes is the study of artificial bilayer membranes. Membranes made from a single lipid species (19, 20) The publication costs ofthis article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.

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Rotational diffusion of bacteriorhodopsin in lipid membranes

Cited by 68 publications

References 23 publications

Phosphorescence depolarization and the measurement of rotational motion of proteins in membranes

Phosphorescence depolarization and the measurement of rotational motion of proteins in membranes

Rotation motion and flexibility of calcium(2+),magnesium(2+)-dependent adenosine 5'-triphosphatase in sarcoplasmic reticulum membranes

Lateral and rotational diffusion of bacteriorhodopsin in lipid bilayers: experimental test of the Saffman-Delbrück equations.

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