Cooperativity‐regulated parallel pathways of the bacteriorhodopsin photocycle

Tokaji, Zsolt

doi:10.1016/0014-5793(94)01344-z

Cited by 16 publications

(16 citation statements)

References 12 publications

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“…A related finding is the negative cooperativity for the rate of M decay, but positive cooperativity for the decay of N (19,20). These cooperativities will have originated from increase of lateral pressure in the plane of the membrane, the result of steric interference of bacteriorhodopsin molecules with one another in the purple membrane lattice.…”

mentioning

confidence: 93%

Coupling of the Reisomerization of the Retinal, Proton Uptake, and Reprotonation of Asp-96 in the N Photointermediate of Bacteriorhodopsin

et al. 2001

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In the N to O reaction of the bacteriorhodopsin photocycle, Asp-96 is protonated from the cytoplasmic surface, and coupled to this, the retinal isomerizes from 13-cis,15-anti back to the initial all-trans configuration. To dissect the two steps, and to better understand how and why they occur, we describe the properties of two groups of site-specific mutants in which the N intermediate has greatly increased lifetime. In the first group, with the mutations near the retinal, an unusual N state is produced in which the retinal is 13-cis,15-anti but Asp-96 has a protonated carboxyl group. The apparent pK(a) for the protonation is 7.5, as in the wild-type. It is likely that here the interference with N decay is the result of steric conflict of side-chains with the retinal or with the side-chain of Lys-216 connected to the retinal, which delays the reisomerization after protonation of Asp-96. In the second group, with the mutations located near Asp-96 or between Asp-96 and the cytoplasmic surface, reprotonation of Asp-96 is strongly perturbed. The reisomerization of the retinal occurs only after recovery from a long-living protein conformation in which reprotonation of Asp-96 is either entirely blocked or blocked at low pH.

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confidence: 93%

Coupling of the Reisomerization of the Retinal, Proton Uptake, and Reprotonation of Asp-96 in the N Photointermediate of Bacteriorhodopsin

et al. 2001

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“…The extended model constructed here supposes that the molecules in these states interact with their neighbors as if they were photocycling. This means that a molecule on the suitable side upon excitation will turn over through the pathway (M s →BR) that is usually induced by its neighbor photocycling [7].…”

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confidence: 99%

Quantitative model for the cooperative interaction of the bacteriorhodopsin molecules in purple membranes

Tokaji

1998

FEBS Letters

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The trimeric, asymmetric and sequential model for the cooperative interaction of the bacteriorhodopsin molecules in purple membranes [Zs. Tokaji, Biophys. J. 65 (1993) 1130^1134] is being extended in the paper. Analyses of data from absorption kinetic measurements with preexcitation and green background illumination, and photoselection measurements on oriented samples confirm the main features of this cooperative interaction and support the validity of the extended model. This model includes the observed heterogeneity of the non-excited state of the bacteriorhodopsin molecules in purple membranes, and the agreement with the data suggests that molecules in any other state than the bacteriorhodopsin ground state can alter the photocycle of their neighbors. The presented results seem to contradict other models for the cooperation of the bacteriorhodopsin molecules.z 1998 Federation of European Biochemical Societies.

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“…For excitation an excimer-laser-pumped dye laser containing coumarin 307 (A. e = 505 nm, 10 ns pulse duration) was used [6].…”

Section: Methodsmentioning

confidence: 99%

“…Derivation of the kinetics of the intermediates was carried out using a method based on transformations and subtractions of the signals [6] with the assumptions described below.…”

Section: Methodsmentioning

confidence: 99%

N‐like intermediate in the photocycle of the acid purple form of bacteriorhodopsin

Tokaji¹,

Dér²,

Keszthelyi³

1997

FEBS Letters

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Cooperativity‐regulated parallel pathways of the bacteriorhodopsin photocycle

Cited by 16 publications

References 12 publications

Coupling of the Reisomerization of the Retinal, Proton Uptake, and Reprotonation of Asp-96 in the N Photointermediate of Bacteriorhodopsin

Coupling of the Reisomerization of the Retinal, Proton Uptake, and Reprotonation of Asp-96 in the N Photointermediate of Bacteriorhodopsin

Quantitative model for the cooperative interaction of the bacteriorhodopsin molecules in purple membranes

N‐like intermediate in the photocycle of the acid purple form of bacteriorhodopsin

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