Skip to main content
NCBI home page
Biophysical Journal logoLink to Biophysical Journal
. 1995 Nov;69(5):2060–2065. doi: 10.1016/S0006-3495(95)80076-7

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

G I Groma 1, J Hebling 1, C Ludwig 1, J Kuhl 1
PMCID: PMC1236439  PMID: 8580349

Abstract

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.

Full text

PDF
2060

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bazhenov V., Schmidt P., Atkinson G. H. Nanosecond photolytic interruption of bacteriorhodopsin photocycle: K-590 --> BR-570 reaction. Biophys J. 1992 Jun;61(6):1630–1637. doi: 10.1016/S0006-3495(92)81966-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Birge R. R. Nature of the primary photochemical events in rhodopsin and bacteriorhodopsin. Biochim Biophys Acta. 1990 Apr 26;1016(3):293–327. doi: 10.1016/0005-2728(90)90163-x. [DOI] [PubMed] [Google Scholar]
  3. Delaney J. K., Brack T. L., Atkinson G. H. Time-resolved absorption and fluorescence from the bacteriorhodopsin photocycle in the nanosecond time regime. Biophys J. 1993 May;64(5):1512–1519. doi: 10.1016/S0006-3495(93)81520-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Govindjee R., Balashov S. P., Ebrey T. G. Quantum efficiency of the photochemical cycle of bacteriorhodopsin. Biophys J. 1990 Sep;58(3):597–608. doi: 10.1016/S0006-3495(90)82403-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Lanyi J. K. Proton transfer and energy coupling in the bacteriorhodopsin photocycle. J Bioenerg Biomembr. 1992 Apr;24(2):169–179. doi: 10.1007/BF00762675. [DOI] [PubMed] [Google Scholar]
  6. Mathies R. A., Brito Cruz C. H., Pollard W. T., Shank C. V. Direct observation of the femtosecond excited-state cis-trans isomerization in bacteriorhodopsin. Science. 1988 May 6;240(4853):777–779. doi: 10.1126/science.3363359. [DOI] [PubMed] [Google Scholar]
  7. Mathies R. A., Lin S. W., Ames J. B., Pollard W. T. From femtoseconds to biology: mechanism of bacteriorhodopsin's light-driven proton pump. Annu Rev Biophys Biophys Chem. 1991;20:491–518. doi: 10.1146/annurev.bb.20.060191.002423. [DOI] [PubMed] [Google Scholar]
  8. Milder S. J., Kliger D. S. A time-resolved spectral study of the K and KL intermediates of bacteriorhodopsin. Biophys J. 1988 Mar;53(3):465–468. doi: 10.1016/S0006-3495(88)83124-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Oesterhelt D., Stoeckenius W. Isolation of the cell membrane of Halobacterium halobium and its fractionation into red and purple membrane. Methods Enzymol. 1974;31:667–678. doi: 10.1016/0076-6879(74)31072-5. [DOI] [PubMed] [Google Scholar]
  10. Oesterhelt D., Tittor J. Two pumps, one principle: light-driven ion transport in halobacteria. Trends Biochem Sci. 1989 Feb;14(2):57–61. doi: 10.1016/0968-0004(89)90044-3. [DOI] [PubMed] [Google Scholar]
  12. Polland H. J., Franz M. A., Zinth W., Kaiser W., Kölling E., Oesterhelt D. Early picosecond events in the photocycle of bacteriorhodopsin. Biophys J. 1986 Mar;49(3):651–662. doi: 10.1016/S0006-3495(86)83692-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Simmeth R., Rayfield G. W. Evidence that the photoelectric response of bacteriorhodopsin occurs in less than 5 picoseconds. Biophys J. 1990 May;57(5):1099–1101. doi: 10.1016/S0006-3495(90)82629-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Song L., El-Sayed M. A., Lanyi J. K. Protein catalysis of the retinal subpicosecond photoisomerization in the primary process of bacteriorhodopsin photosynthesis. Science. 1993 Aug 13;261(5123):891–894. doi: 10.1126/science.261.5123.891. [DOI] [PubMed] [Google Scholar]
  15. Stoeckenius W., Lozier R. H., Bogomolni R. A. Bacteriorhodopsin and the purple membrane of halobacteria. Biochim Biophys Acta. 1979 Mar 14;505(3-4):215–278. doi: 10.1016/0304-4173(79)90006-5. [DOI] [PubMed] [Google Scholar]
  16. Váró G., Keszthelyi L. Photoelectric signals from dried oriented purple membranes of Halobacterium halobium. Biophys J. 1983 Jul;43(1):47–51. doi: 10.1016/S0006-3495(83)84322-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Váró G., Lanyi J. K. Distortions in the photocycle of bacteriorhodopsin at moderate dehydration. Biophys J. 1991 Feb;59(2):313–322. doi: 10.1016/S0006-3495(91)82225-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. van den Berg R., Du-Jeon-Jang, Bitting H. C., El-Sayed M. A. Subpicosecond resonance Raman spectra of the early intermediates in the photocycle of bacteriorhodopsin. Biophys J. 1990 Jul;58(1):135–141. doi: 10.1016/S0006-3495(90)82359-6. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society

RESOURCES