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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1979 Feb;76(2):770–773. doi: 10.1073/pnas.76.2.770

Spectral and kinetic evidence for two early electron acceptors in photosystem I

Vladimir A Shuvalov 1,†, Ed Dolan 1, Bacon Ke 1,‡
PMCID: PMC383046  PMID: 16592621

Abstract

Triton-fractionated photosystem-I particles poised at -625 mV, where the two bound iron-sulfur proteins are reduced, have been studied by optical and electron paramagnetic resonance spectroscopies from 293 to 5 K. At 5-9 K, these particles exhibit two decay components with lifetimes of 1.3 and 130 msec in the laser pulse-induced absorption and electron paramagnetic resonance signal changes. Spectral properties of the 130-msec decay component reflect the charge separation between P-700 and some iron-sulfur center having a broad optical absorbance in the 400- to 550-nm region and a previously reported electron paramagnetic resonance signal with g = 1.78, 1.88, and 2.08. Spectral properties of the 1-msec decay component indicate photoinduced charge separation between P-700 and a chlorophyll a dimer having absorption bands at 420, 450, and 700 nm. It is assumed that these two acceptors participate in the electron transfer from P-700* to the bound iron-sulfur proteins.

Keywords: electron transfer, chlorophyll photoreduction

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Selected References

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

  1. Bacon K. E., Sugahara K., Shaw E. R., Hansen R. E., Hamilton W. D., Beinert H. Kinetics of appearance and disappearance of light-induced EPR signals of P700+ and iron-sulfur proteins(s) at low temperature. Biochim Biophys Acta. 1974 Dec 19;368(3):401–408. doi: 10.1016/0005-2728(74)90185-6. [DOI] [PubMed] [Google Scholar]
  2. Evans M. C., Reeves S. G., Cammack R. Determination of the oxidation-reduction potential of the bound iron-sulphur proteins of the primary electron acceptor complex of photosystem I in spinach chloroplasts. FEBS Lett. 1974 Dec 1;49(1):111–114. doi: 10.1016/0014-5793(74)80644-7. [DOI] [PubMed] [Google Scholar]
  3. Hiyama T., Ke B. A new photosynthetic pigment, "P430": its possible role as the priary electron acceptor of photosystem I. Proc Natl Acad Sci U S A. 1971 May;68(5):1010–1013. doi: 10.1073/pnas.68.5.1010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Ke B., Beinert H. Evidence for the identity of P430 of Photosystem I and chloroplast-bound iron-sulfur protein. Biochim Biophys Acta. 1973 Jun 28;305(3):689–693. doi: 10.1016/0005-2728(73)90094-7. [DOI] [PubMed] [Google Scholar]
  5. Ke B. Flash kinetic spectrophotometry. Methods Enzymol. 1972;24:25–53. doi: 10.1016/0076-6879(72)24053-8. [DOI] [PubMed] [Google Scholar]
  6. Ke B., Hansen R. E., Beinert H. Oxidation-reduction potentials of bound iron-sulfur proteins of photosystem I. Proc Natl Acad Sci U S A. 1973 Oct;70(10):2941–2945. doi: 10.1073/pnas.70.10.2941. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Ke B., Sahu S., Elwood S., Beinert H. Further characterization of a photosystem-II particle isolated from spinach chloroplasts by triton treatment: the reaction-center components. Biochim Biophys Acta. 1974 Apr 23;347(1):36–48. doi: 10.1016/0005-2728(74)90198-4. [DOI] [PubMed] [Google Scholar]
  8. Ke B. The primary electron acceptor of photosystem. I. Biochim Biophys Acta. 1973 Feb 12;301(1):1–33. doi: 10.1016/0304-4173(73)90010-4. [DOI] [PubMed] [Google Scholar]
  9. Malkin R., Bearden A. J. Primary reactions of photosynthesis: photoreduction of a bound chloroplast ferredoxin at low temperature as detected by EPR spectroscopy. Proc Natl Acad Sci U S A. 1971 Jan;68(1):16–19. doi: 10.1073/pnas.68.1.16. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. McIntosh A. R., Chu M., Bolton J. R. Flash photolysis electron spin resonance studies of the electron acceptor species at low temperatures in photosystem I of spinach subchloroplast particles. Biochim Biophys Acta. 1975 Feb 17;376(2):308–314. doi: 10.1016/0005-2728(75)90023-7. [DOI] [PubMed] [Google Scholar]
  11. Sauer K., Mathis P., Acker S., van Best J. A. Electron acceptors associated with P-700 in Triton solubilized photosystem I particles from spinach chloroplasts. Biochim Biophys Acta. 1978 Jul 6;503(1):120–134. doi: 10.1016/0005-2728(78)90166-4. [DOI] [PubMed] [Google Scholar]
  12. Shuvalov V. A., Klimov V. V., Krasnovskii A. A. Issledovanie pervichnykh fotoprotsessov v legkikh fragmentakh khloroplastov. Mol Biol (Mosk) 1976 Mar-Apr;10(2):326–339. [PubMed] [Google Scholar]
  13. Shuvalov V. A. The study of the primary photoprocesses in photosystem I of chloroplasts. Recombination luminescence, chlorophyll triplet state and triplet-triplet annihilation. Biochim Biophys Acta. 1976 Apr 9;430(1):113–121. doi: 10.1016/0005-2728(76)90227-9. [DOI] [PubMed] [Google Scholar]
  14. Visser J. W., Rijgersberg K. P., Amesz J. Light-induced reactions of ferredoxin and P700 at low temperatures. Biochim Biophys Acta. 1974 Nov 19;368(2):235–246. doi: 10.1016/0005-2728(74)90152-2. [DOI] [PubMed] [Google Scholar]

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