The Possible Existence of a Charge Transfer State which Preceeds the Formation of (BChl)2+ BPh in Rhodobacter sphaeroides Reaction Centers

  • P. Leslie Dutton
  • Guillermo Alegria
  • M. R. Gunner
Part of the NATO ASI Series book series (NSSA, volume 149)


The nature of the first electron transfer step in the photosynthetic reaction center protein is far from certain. Several investigators have considered a monomeric BChl to be important in promoting forward electron transfer from (BChl)2* to BPh. The center of the BChl is positioned in the X-ray crystal structure 0.25nm from the center of the (BChl)2, measured in a direction parallel with the z-axis of the protein (4,5). The monomer is displaced out of the direct line joining (BChl)2 and BPh centers but nevertheless it remains an obvious candidate to be on the electron transfer reaction pathway. However, careful searches in the picosecond time domain for absorbance changes that may be associated with transient redox changes on the BChl have failed to demonstrate its involvment in the sequence over a wide temperature range (1–3 although see ref. 6). Instead, spectroscopic investigations with picosecond and subpicosecond resolution have revealed that the loss of the excited singlet state of the special pair of bacteriochlorophylls, (BChl)2*, coincides with the appearance of the reduced bacteriopheophytin (BPh). Thus, the formation of the state (BChl)2 + BPh, which is positioned some 0.2ev below the (BChl)2* state appears to occur in a single step with a rate of approximately 3×1011 s−1 (1–3). This separates charge across the approximately 1.1 nm between the centers of the (BChl)2 and BPh, again measured along the line parallel to the z-axis of the protein (4,5). Because of the closly matched kinetics of (BChl)2* decay and BPh appearance, the involvement of BChl as a conventional redox carrier is cryptic and in doubt. However, it is acknowledged in these studies that, for technical reasons, levels of BChl+ or BChl must achieve 15% of the total reaction center population to be detected with any certainty. Thus, there are several viable models (see refs 1–3,6,7–10 for discussion) that can explain these early steps in photosynthesis leading to formation of (BChl)2 + BPh. These include:
  1. 1.

    The BChl plays no part in electron transfer from (BChl)2 to BPh.

  2. 2.

    The BChl serves to increase the electron coupling between (BChl)2 and BPh by the mechanism of superexchange.

  3. 3.

    The BChl is a bona fide redox agent that accepts an electron from (BChl)2* to form (BChl)2 + BChl which is followed by electron donation to BPh.

  4. 4.

    The BChl is a bona fide redox agent, but the reaction sequence is that singlet energy transfer from (BChl)2* to BChl first induces an electron transfer from BChl to BPh to form BChl+BPh. The cation BChl+ so formed then moves to the (BChl)2.



Electron Transfer Reaction Center Charge Transfer State Effective Dielectric Constant Monolayer Film 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Kirmaier C, Holten, D and Parson W.W. FEBS Letters 185; 76–82 (au]).Google Scholar
  2. 2.
    Woodbury N.W., Becker M, Middendorf D and Parson W.W. Biochemistry 24; 7516–7521 (1985).PubMedCrossRefGoogle Scholar
  3. 3.
    Martin J-L, Breton, J, Hoff A.J., Migus, A., and Antonetti, A. Proc. Natl Acad Sci; U.S.A. 83 957–961 (1986).PubMedCrossRefGoogle Scholar
  4. 4.
    Allen, J.P., Feher, G., Yeates, T.O., Komiya, H and Rees, D.C., Proc Natl Acad Sci; U.S.A. 84 5730–5734 1987.PubMedCrossRefGoogle Scholar
  5. 5.
    Chang, C.H., Tiède, D.M., Tang, J., Smith, U., Norris, J., and Schiffer, M.; FEBS Letts. 205 82–86 (1986).CrossRefGoogle Scholar
  6. 6.
    Shuvalov V.A., and Klenanik V.A., FEBS Letters 160 51–55 (1983).CrossRefGoogle Scholar
  7. 7.
    Marcus R.A., Chem. Phys. Letters 133 471–477 (1987).CrossRefGoogle Scholar
  8. 8.
    Haberkorn, R., Michel-Beyerle, M.E. and Marcus, R.A., Proc. Natl Acad Sci U.S.A. 76 4185–4189 (1979).PubMedCrossRefGoogle Scholar
  9. 9.
    Kirmaier, C., Holten D., Parson, W.W. Biochim Biophys Acta 810 33–42 (1985).CrossRefGoogle Scholar
  10. 10.
    Holten D., Hoganson C., Windsor M.W., Schenck C.C., Parson W.W., Migus A., Fork R.L., and Shank C.V., Biochim Biophvs Acta. 592 461–473 (1980).CrossRefGoogle Scholar
  11. 11.
    Popovic Z.D., Kovacs, G.J., Vincett, P.S., Alegria, G., and Dutton, P.L. Biochim, Biophys Acta 851 38–48 (1986).CrossRefGoogle Scholar
  12. 12.
    Gunner, M.R., and Dutton, P.L. Accompaning manuscript, this volume.Google Scholar
  13. 13.
    Gunner, M.R., and Dutton, P.L. Submitted to Biophys J.Google Scholar
  14. 14.
    Dutton, P.L., Alegria, A., and Gunner, M.R. Biophys J. Abstracts for Biophysical Meeting. February. (1988).Google Scholar
  15. 15.
    Wraight, C.A. and Clayton, R.K., Biochim Biophys Acta.Google Scholar
  16. 16.
    Cho, H.M., Mancino, L.J., and Blankenship, R.E., Biophys J 45 455–461 (1984).PubMedCrossRefGoogle Scholar
  17. 17.
    Loach, P.A., and Sekura, D.L., Biochemistry 7, 2642–2649 (1968).PubMedCrossRefGoogle Scholar
  18. 18.
    Popovic, Z.D., Kovacs, G.J., Vincett, P.S. and Dutton, P.L. Dutton, Chem Phys Letts 116 405–410 (1985).CrossRefGoogle Scholar
  19. 19.
    Popovic, Z.D., Kovacs, G.J., Vincett, P.S., Alegria, G., Dutton, P.L., Chem. Phys 110 227–237 (1986).CrossRefGoogle Scholar
  20. 20.
    Gopher, A., Blatt, Y., Schoenfeld, M., Okamura, M.Y., Feher, G., and Montai, M., Biophvs J 48. 311–320 (1985).CrossRefGoogle Scholar
  21. 21.
    Packham, N.K., Mueller, P., and Dutton, P.L., Biochim Biophys Acta In press.Google Scholar
  22. 22.
    Feher, G., Arno, T.R., and Okamura, M.Y., This volume.Google Scholar
  23. 23.
    Campillo, A.J., Hyer, R.C., Monger, T.G., Parson, W.W., and Shapiro, S.L., Proc Natl Acad Sci U.S.A. 74 1997–2001 (1977).PubMedCrossRefGoogle Scholar
  24. 24.
    Leigh, J.S., and Dutton, P.L., Biochem Biophys Res. Comm 46 414–418 (1972).PubMedCrossRefGoogle Scholar
  25. 25.
    Tiede, D.M., Prince, R.C., and Dutton, P.L., Biochim Biophys Acta 449 447–467 (1976).PubMedCrossRefGoogle Scholar
  26. 26.
    Prince, R.C., Tiede, D.M., Thornber, J.P., and Dutton, P.L., Biochim Biophys Acat 462 731–747 (1977).CrossRefGoogle Scholar
  27. 27.
    Prince, R.C., Dutton, P.L., Clayton, R.K., Biochim Biophys Acta 502 354–358 (1978).PubMedCrossRefGoogle Scholar
  28. 28.
    Tiede, D.M., Mueller, P., and Dutton, P.L., Biochim Biophys Acta 681 191–201 (1982).CrossRefGoogle Scholar
  29. 29.
    Alegria, G., and Dutton, P.L., In “Cytochrome Systems: Molecular Biology and Bioenergetics” (S. Papa, B. Chance, L. Ernster and J. Jaz eds). Plenum Press, London. In press, (1987).Google Scholar
  30. 30.
    Netzel, T.L., Rentzepis, P.M., Tiede, D.M., Prince, R.C., and Dutton, P.L., Biochim Biophvs Acta 460 467–479 (1977).CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1988

Authors and Affiliations

  • P. Leslie Dutton
    • 1
  • Guillermo Alegria
    • 1
  • M. R. Gunner
    • 1
  1. 1.Department of Biochemistry and BiophysicsUniversity of PennslyvaniaPhiladelphiaUSA

Personalised recommendations