Molecular dynamics of the primary photochemical event in bacteriorhodopsin. Theoretical evidence for an excited singlet state assignment for the J intermediate

Birge, Robert R.; Findsen, Leonore A.; Pierce, Brian M.

doi:10.1021/ja00250a056

Cited by 34 publications

(21 citation statements)

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“…Results from two other studies (57,58) are consistent with the observations reported here. Specifically, the reduced Stokes shift and larger fluorescence yield for K-590 may reflect the storage of energy in K-590 (-15 kcal/mol) resulting from the primary photocycle events (57).…”

Section: Discussionsupporting

confidence: 91%

“…Specifically, the reduced Stokes shift and larger fluorescence yield for K-590 may reflect the storage of energy in K-590 (-15 kcal/mol) resulting from the primary photocycle events (57). These observations also are consistent with model calculations which utilize the C13-=CI4 torsion as the major reaction coordinate underlying the primary photochemistry (58). These calculations conclude that the excited-state relaxation away from the Franck-Condon states initially populated in absorption is slower in K* than in BR*, thus suggesting that fluorescence from K* should appear to the blue of fluorescence from BR*.…”

Section: Discussionsupporting

confidence: 76%

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Picosecond time-resolved fluorescence spectroscopy of K-590 in the bacteriorhodopsin photocycle

Atkinson

Blanchard

Lemaire

et al. 1989

Biophysical Journal

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The fluorescence spectrum of a distinct isometric and conformational intermediate formed on the 10(-11) s time scale during the bacteriorhodopsin (BR) photocycle is observed at room temperature using a two laser, pump-probe technique with picosecond time resolution. The BR photocycle is initiated by pulsed (8 ps) excitation at 565 nm, whereas the fluorescence is generated by 4-ps laser pulses at 590 nm. The unstructured fluorescence extends from 650 to 880 nm and appears in the same general spectral region as the fluorescence spectrum assigned to BR-570. The transient fluorescence spectrum can be distinguished from that assigned to BR-570 by a larger emission quantum yield (approximately twice that of BR-570) and by a maximum intensity near 731 nm (shifted 17 nm to higher energy from the maximum of the BR-570 fluorescence spectrum). The fluorescence spectrum of BR-570 only is measured with low energy, picosecond pulsed excitation at 590 nm and is in good agreement with recent data in the literature. The assignment of the transient fluorescence spectrum to the K-590 intermediate is based on its appearance at time delays longer than 40 ps. The K-590 fluorescence spectrum remains unchanged over the entire 40-100-ps interval. The relevance of these fluorescence data with respect to the molecular mechanism used to model the primary processes in the BR photocycle also is discussed.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 76%

Picosecond time-resolved fluorescence spectroscopy of K-590 in the bacteriorhodopsin photocycle

Atkinson

Blanchard

Lemaire

et al. 1989

Biophysical Journal

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“…This has been predicted in molecular dynamics simulations by Birge et a1. 62 El-Sayed and coworkers probed the excited-state absorption decay, ground-state recovery, and reaction quantum yield as a function of pH and observed a rate reduction by a factor of 2, without a change in quantum yield, after increase of the pH from 6.8 to 11.3. 19 • 61 They assumed a single channel excited state in which ground-state recovery is the only alternative to reaction.…”

Section: Is the Reaction Pathway Homogeneous Or Inhomogeneous?mentioning

confidence: 99%

Ultrafast Spectroscopy of Rhodopsins — Photochemistry at Its Best!

Kochendoerfer

Mathies

1995

Israel Journal of Chemistry

110

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Recent advances inlaser technology nowallow usto studythe ultrafast primaryphotochemical eventsin rhodopsin, bacteriorhodopsin, and halorhodopsin in real time.The resultsof various ultrafaststudiesof rhodopsins are reviewed with an emphasis on (1) the relationship between the reaction rate andreaction efficiency and its implications for the mechanism of isomerization, (2) the homogeneity of the reaction pathways, and (3) the role of the protein in the reaction dynamics. The results mandate the introduction of a new paradigm to describe these ultrafast reactions that specifically considers the importance of the timescale of vibrational dephasing and relaxation relative to the reactive motion and the contribution of vibrational coherence to the reaction mechanism.

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“…An alternative suggestion (Polland et al, 1986) interprets the J -+ K process in terms of dissipation of excess thermal energy generated in the retinal moiety following excitation, thus identifying J as a hot (13-cis) ground state species. Finally, on the basis of theoretical calculations, J has been recently assigned to a secondary excited state, formed from a primary excited state (identified as the 1 intermediates) in parallel to the I ~ K process (Birge, Findson & Pierce, 1987). This approach seems unlikely, mainly since there is no component in the bR fluorescence which matches the 4-psec decay of J.…”

Section: J and Photomentioning

confidence: 99%

Synthetic retinals as probes for the binding site and photoreactions in rhodopsins

Ottolenghi

Sheves

1989

J. Membrain Biol.

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Molecular dynamics of the primary photochemical event in bacteriorhodopsin. Theoretical evidence for an excited singlet state assignment for the J intermediate

Cited by 34 publications

References 0 publications

Picosecond time-resolved fluorescence spectroscopy of K-590 in the bacteriorhodopsin photocycle

Picosecond time-resolved fluorescence spectroscopy of K-590 in the bacteriorhodopsin photocycle

Ultrafast Spectroscopy of Rhodopsins — Photochemistry at Its Best!

Synthetic retinals as probes for the binding site and photoreactions in rhodopsins

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