Rotational diffusion and exciton coupling of bacteriorhodopsin in the cell membrane of <i>Halobacterium halobium</i>

Cherry, Richard J.

doi:10.1016/0014-5793(77)80265-2

Cited by 62 publications

(24 citation statements)

References 18 publications

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“…1. The slow decay of rM(t) is almost the same with that of measured anisotropies for wild-type bR [5,8]. The reported results were attributed to the rotational motion of purple membrane sheet itself.…”

Section: E57osupporting

confidence: 85%

“…Thus, the changed conformation of M-intermediate should slow the rotational motion of the monomer protein or lead the binding between M-intermediate and neighboring proteins. For wild-type bR, whether the protein undergoes the motion in the purple membrane is still an open question [4][5][6][7][8][9][10][11]. For D96N, however, we confirmed that non-excited molecules rotate within the membrane.…”

Section: E57omentioning

confidence: 50%

“…For detection of the motion, absorption anisotropy becomes a powerful tool. Using this method, however, an absence of the motion of retinal was reported [4][5][6][7][8]. The immobilization of the retinal was explained by the restriction with peptide chains around retinal and the rigid structure of the purple membrane.…”

Section: Introductionmentioning

confidence: 95%

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The molecular motion of bacteriorhodopsin mutant D96N in the purple membrane

et al. 1995

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We measured the flash-induced absorption anisotropies of mutant bacteriorhodopsin (bR), D96N, in the purple membrane suspension. The measured anisotropy decay at 410 nm differed from that at 570 nm. These wavelength-dependent anisotropies show that the motion of absorption dipole of non-excited bR is faster than that of M-intermediate. The motion of nonexcited bR is considered as the rotational motion of whole protein in the purple membrane. This fact suggests that the photo-excitation induces the conformational change of the protein and/or the inter-protein interaction within the membrane, which prevents the motion of M-intermediate.

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Section: E57osupporting

confidence: 85%

Section: E57omentioning

confidence: 50%

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The molecular motion of bacteriorhodopsin mutant D96N in the purple membrane

et al. 1995

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“…There has been a number of trials to find out whether the parts of the bacteriorhodopsin molecules move or not during the proton pumping photocycle. It has been proved that the retinal, the chromophore of the protein, does not move [1][2][3][4][5] and no motion of the protein side chains has been found [6]. On the other hand, evidence exists for movement: by increasing the solvent viscosity with glycerol, some steps of the photocycle slow down [7] and then the proton movement can be directly demonstrated by the PERS method [8].…”

Section: Introductionmentioning

confidence: 99%

Light scattering changes and protein distortion in the bacteriorhodopsin during the photocycle

Czégé

1988

FEBS Letters

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A change in light scattering was detected during the photoeycle of the purple membrane. A systematic study of the pH, viscosity and photoseleetion dependence of scattering kinetics is given. From the experimental data it follows that purple membranes are bent, depending on the pH, and that the extent of bending changes during the photocycle is due to the functional protein. A theoretical treatment is also given. The model explains all the experimental data and, as an important consequence, calls attention to the fact that exact kinetic measurements cannot be performed without immobilizing the purple membranes.

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“…Photoselection is a convenient method for this purpose. Photoselection measurements on bR have been reported only in the visible range, however (1)(2)(3)(4)(5)(6)(7)(8)(9).…”

mentioning

confidence: 99%

Restriction of motion of protein side chains during the photocycle of bacteriorhodopsin.

Czégé¹,

Dér²,

Zimányi³

et al. 1982

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

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Linear dichroism was measured during the photocycle of bacteriorhodopsin. The anisotropy of the sample was produced by the photoselection method. The measurements on purple membrane fragments embedded in agar gel were performed at room temperature with 200-psec time resolution at several wavelengths in the 240-to 550-nm spectral region. The induced anisotropy of the retinal chromophore remained constant after the formation of the photocycle intermediate M. The anisotropy was also time independent at the characteristic peaks ofthe UV absorption change. These-experimental data suggest that the direction of the retinal transition dipole moment remains unchanged. Moreover, the affected aromatic protein side chains also do not show any rotational motion when they are in the perturbed or ground states during the photocycle. Our data render it possible to calculate the restricted range of sudden chromophore rotations that might be coupled to the appearance and decay of the M intermediate.A study of chromophore orientation in bacteriorhodopsin (bR) during its photocycle can provide valuable information about the proton-pumping mechanism of this molecule. Photoselection is a convenient method for this purpose. Photoselection measurements on bR have been reported only in the visible range, however (1-9).Slow decay of the induced dichroism of the retinal chromophore at different wavelengths caused by the rotational diffusion ofpurple membranes (PMs) has been observed in aqueous solution (4,5,8). Small, fast changes in the polarization anisotropy also have been reported and attributed to some conformational changes ofthe protein during the photocycle (4, 5). These transients disappeared, however, when PMs were immobilized in polyacrylamide gel, indicating that the fast decay was probably due to rotational diffusion of small membrane fragments (10). Transient dichroism data obtained on bR incorporated into phosphatidylcholine vesicles (9) have shown that the bRs are immobilized below the lipid phase transition temperature and rotate above it. The slow transition of light-adapted bR to the dark-adapted form has been measured by the photoselection method at 530 nm on-thin layers containing PM (11). This experiment indicated that both the bR molecules in the PM and the visible retinal chromophore in the ground state are immobilized. Recently, however, changes -of the photodichroism in the visible range during the photocycle have been measured and interpreted as a result ofrotational displacement ofthe retinal chromophore (7).The spectrum ofthe UV absorption change indicates that the aromatic amino acid residues of the protein participate in the proton-pumping mechanism (12-14). These transients in films containing PM have been found to be dichroic, suggesting that only few residues are involved (14). The formation and decay times have been correlated with the steps ofthe photocycle (15, 16).Here we report photoselection measurement on PM performed in a wide wavelength range (240-550 nm). PMs were immobilized in ==1% ag...

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Rotational diffusion and exciton coupling of bacteriorhodopsin in the cell membrane of Halobacterium halobium

Cited by 62 publications

References 18 publications

The molecular motion of bacteriorhodopsin mutant D96N in the purple membrane

The molecular motion of bacteriorhodopsin mutant D96N in the purple membrane

Light scattering changes and protein distortion in the bacteriorhodopsin during the photocycle

Restriction of motion of protein side chains during the photocycle of bacteriorhodopsin.

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