Picosecond Spectroscopy on Reverse Photoreaction from Batho-Intermediate of Bacteriorhodopsin at 6.5 K

Iwasa, Takeshi; Suzuki, Yôiti; Nakayama, Tomoyuki; Tokunaga, Fumio; Hirai, Masamitsu

doi:10.1143/jpsj.53.2851

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…What is important is that the charge displacement in the reverse photoreaction is faster than in the forward one. This is in agreement with previous optical studies (Kryukov et al, 1981;Iwasa et al, 1984). Our direct electric method significantly extended the time resolution of the reverse photoreaction, giving a 3.5 ps upper limit for its time constant.…”

Section: Resultssupporting

confidence: 94%

“…There is no chance, however, for the excitation of the extremely short-lived J intermediate. The existence of the photo-induced reverse reaction from K to bR is a well known phenomenon (Kryukov et al, 1981;Iwasa et al, 1984;Birge et al, 1989;Govindjee et al, 1990;Bazhenov et al, 1992), whereas no similar reaction has been reported for L. Clearly, the corresponding charge movement should have the opposite direction than that of the forward reaction. Such a reversed electric signal was demonstrated experimentally by double flash experiments (Ormos et al, 1983;Trissl et al, 1989).…”

Section: Resultsmentioning

confidence: 98%

“…Reverse photoreaction from K to bR was demonstrated by accumulation of K at low temperature (Birge et al, 1989, and references cited there) by photoequilibrium measurements at room temperature (Govindjee et al, 1990) and by double-pump excitation (Bazhenov et al, 1992). Low temperature absorption kinetic experiments of 30 ps time resolution indicate that the overall rate of the reverse photoreaction is higher than that of the forward one (Kryukov et al, 1981, Iwasa et al, 1984. However, the detailed path and kinetics of the K-*bR back photoreaction are still unknown.…”

Section: Introductionmentioning

confidence: 99%

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Charge displacement in bacteriorhodopsin during the forward and reverse bR-K phototransition

Groma

Hebling

Ludwig

et al. 1995

Biophysical Journal

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Dried oriented purple membrane samples of Halobacterium salinarium were excited by 150 fs laser pulses of 620 nm with a 7 kHz repetition rate. An unusual complex picosecond electric response signal consisting of a positive and a negative peak was detected by a sampling oscilloscope. The ratio of the two peaks was changed by 1) reducing the repetition rate, 2) varying the intensity of the excitation beam, and 3) applying background illumination by light of 647 nm or 511 nm. All of these features can be explained by the simultaneous excitation of the bacteriorhodopsin ground form and the K intermediate. The latter was populated by the (quasi)continuous excitation attributable to its prolonged lifetime in a dehydrated state. Least-square analysis resulted in a 5 ps upper and 2.5 ps lower limit for the time constant of the charge displacement process, corresponding to the forward reaction. That is in good agreement with the formation time of K. The charge separation driven by the reverse phototransition was faster, having a time constant of a 3.5 ps upper limit. The difference in the rates indicates the existence of different routes for the forward and the reverse photoreactions.

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Section: Resultssupporting

confidence: 94%