Skip to main content
NCBI home page
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
. 1973 Feb;70(2):294–297. doi: 10.1073/pnas.70.2.294

Detection of a Free Radical in the Primary Reaction of Chloroplast Photosystem II

Richard Malkin *, Alan J Bearden †
PMCID: PMC433242  PMID: 16592053

Abstract

Electron paramagnetic resonance (EPR) spectroscopy has revealed a new free-radical signal produced by illumination of spinach chloroplasts at 77°K. This signal is observed only when an oxidant (ferricyanide) is added to the chloroplast suspension in the dark before illumination. The EPR signal is produced at 77°K by illumination with 645-nm monochromatic light capable of activating Photosystem II but not with 715-nm illumination capable of activating Photosystem I. Furthermore, since the signal shows a relative increase in chloroplast fragments enriched in Photosystem II but is absent in chloroplast fragments enriched in Photosystem I, we conclude that this new EPR signal is associated with the primary photoact of Photosystem II in chloroplasts. On the basis of the measured EPR parameters (g = 2.0026 ± 0.0002, linewidth = 8 G), it is suggested that the signal may be associated with the reaction-center chlorophyll of Photosystem II.

Keywords: photosynthesis, electron transfer, light reactions, electron paramagnetic resonance

Full text

PDF
294

Selected References

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

  1. Arnold W., Clayton R. K. THE FIRST STEP IN PHOTOSYNTHESIS: EVIDENCE FOR ITS ELECTRONIC NATURE. Proc Natl Acad Sci U S A. 1960 Jun;46(6):769–776. doi: 10.1073/pnas.46.6.769. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Arnon D. I. COPPER ENZYMES IN ISOLATED CHLOROPLASTS. POLYPHENOLOXIDASE IN BETA VULGARIS. Plant Physiol. 1949 Jan;24(1):1–15. doi: 10.1104/pp.24.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. BEINERT H., KOK B. AN ATTEMPT AT QUANTITATION OF THE SHARP LIGHT-INDUCED ELECTRON PARAMAGNETIC RESONANCE SIGNAL IN PHOTOSYNTHETIC MATERIALS. Biochim Biophys Acta. 1964 Sep 25;88:278–288. doi: 10.1016/0926-6577(64)90183-4. [DOI] [PubMed] [Google Scholar]
  4. Bearden A. J., Malkin R. Quantitative EPR studies of the primary reaction of photosystem I in chloroplasts. Biochim Biophys Acta. 1972 Dec 14;283(3):456–468. doi: 10.1016/0005-2728(72)90262-9. [DOI] [PubMed] [Google Scholar]
  5. Bearden A. J., Malkin R. The bound ferredoxin of chloroplasts: a role as the primary electron acceptor of photosystem I. Biochem Biophys Res Commun. 1972 Feb 16;46(3):1299–1305. doi: 10.1016/s0006-291x(72)80116-5. [DOI] [PubMed] [Google Scholar]
  6. Bendall D. S., Sofrová D. Reactions at 77 degrees K in photosystem 2 of green plants. Biochim Biophys Acta. 1971 Jun 15;234(3):371–380. doi: 10.1016/0005-2728(71)90204-0. [DOI] [PubMed] [Google Scholar]
  7. Boardman N. K., Anderson J. M., Hiller R. G. Photooxidation of cytochromes in leaves and chloroplasts at liquid-nitrogen temperature. Biochim Biophys Acta. 1971 Apr 6;234(1):126–136. doi: 10.1016/0005-2728(71)90137-x. [DOI] [PubMed] [Google Scholar]
  8. Borg D. C., Fajer J., Felton R. H., Dolphin D. The pi-Cation Radical of Chlorophyll a. Proc Natl Acad Sci U S A. 1970 Oct;67(2):813–820. doi: 10.1073/pnas.67.2.813. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Butler W. L., Okayama S. The photoreduction of C-550 in chloroplasts and its inhibition by lipase. Biochim Biophys Acta. 1971 Aug 6;245(1):237–239. doi: 10.1016/0005-2728(71)90028-4. [DOI] [PubMed] [Google Scholar]
  10. Butler W. L. The relationship between P-680 and C-550. Biophys J. 1972 Jul;12(7):851–857. doi: 10.1016/S0006-3495(72)86128-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. COMMONER B., HEISE J. J., LIPPINCOTT B. B., NORBERG R. E., PASSONNEAU J. V., TOWNSEND J. Biological activity of free radicals. Science. 1957 Jul 12;126(3263):57–63. doi: 10.1126/science.126.3263.57. [DOI] [PubMed] [Google Scholar]
  12. Döring G., Renger G., Vater J., Witt H. T. Properties of the photoactive chlorophyll-aII in photosynthesis. Z Naturforsch B. 1969 Sep;24(9):1139–1143. doi: 10.1515/znb-1969-0911. [DOI] [PubMed] [Google Scholar]
  13. Erixon K., Butler W. L. The relationship between Q, C- 550 and cytochrome b 559 in photoreactions at -196 degrees in chloroplasts. Biochim Biophys Acta. 1971 Jun 15;234(3):381–389. doi: 10.1016/0005-2728(71)90205-2. [DOI] [PubMed] [Google Scholar]
  14. Evans M. C., Telfer A., Lord A. V. Evidence for the role of a bound ferredoxin as the primary electron acceptor of photosystem I in spinach chloroplasts. Biochim Biophys Acta. 1972 Jun 23;267(3):530–537. doi: 10.1016/0005-2728(72)90181-8. [DOI] [PubMed] [Google Scholar]
  15. Feher G., Okamura M. Y., McElroy J. D. Identification of an electron acceptor in reaction centers of Rhodopseudomonas spheroides by EPR spectroscopy. Biochim Biophys Acta. 1972 Apr 20;267(1):222–226. doi: 10.1016/0005-2728(72)90155-7. [DOI] [PubMed] [Google Scholar]
  16. Floyd R. A. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea Effect on Cytochrome b(559) Photooxidation and Q Reduction at Temperatures Near 0 C. Plant Physiol. 1972 Mar;49(3):455–456. doi: 10.1104/pp.49.3.455. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Floyd R. A., Chance B., Devault D. Low temperature photo-induced reactions in green leaves and chloroplasts. Biochim Biophys Acta. 1971 Jan 12;226(1):103–112. doi: 10.1016/0005-2728(71)90182-4. [DOI] [PubMed] [Google Scholar]
  18. Govindjee, Döring G., Govindjee R. The active chlorophyll a ii in suspensions of lyophilized and tris-washed chloroplasts. Biochim Biophys Acta. 1970;205(2):303–306. doi: 10.1016/0005-2728(70)90260-4. [DOI] [PubMed] [Google Scholar]
  19. HOCH G., MARTIN I. TWO LIGHT REACTIONS IN TPN REDUCTION BY SPINACH CHLOROPLASTS. Arch Biochem Biophys. 1963 Sep;102:430–438. doi: 10.1016/0003-9861(63)90251-0. [DOI] [PubMed] [Google Scholar]
  20. Hauska G. A., McCarty R. E., Racker E. The site of phosphorylation associated with photosystem. Biochim Biophys Acta. 1970 Mar 3;197(2):206–218. doi: 10.1016/0005-2728(70)90032-0. [DOI] [PubMed] [Google Scholar]
  21. Knaff D. B., Arnon D. I. Spectral evidence for a new photoreactive component of the oxygen-evolving system in photosynthesis. Proc Natl Acad Sci U S A. 1969 Jul;63(3):963–969. doi: 10.1073/pnas.63.3.963. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Leigh J. S., Jr, Dutton P. L. The primary electron acceptor in photosynthesis. Biochem Biophys Res Commun. 1972 Jan 31;46(2):414–421. doi: 10.1016/s0006-291x(72)80154-2. [DOI] [PubMed] [Google Scholar]
  23. Loach P. A., Hall R. L. The question of the primary electron acceptor in bacterial photosynthesis. Proc Natl Acad Sci U S A. 1972 Apr;69(4):786–790. doi: 10.1073/pnas.69.4.786. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. 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]
  25. Malkin R. Photosystem II activity of chloroplast fragments lacking P700. Biochim Biophys Acta. 1971 Dec 7;253(2):421–427. doi: 10.1016/0005-2728(71)90045-4. [DOI] [PubMed] [Google Scholar]
  26. McElroy J. D., Feher G., Mauzerall D. C. Characterization of primary reactants in bacterial photosynthesis. I. Comparison of the light-induced EPR signal (g=2.0026) with that of a bacteriochlorophyll radical. Biochim Biophys Acta. 1972 May 25;267(2):363–374. doi: 10.1016/0005-2728(72)90123-5. [DOI] [PubMed] [Google Scholar]
  27. McElroy J. D., Feher G., Mauzerall D. C. On the nature of the free radical formed during the primary process of bacterial photosynthesis. Biochim Biophys Acta. 1969 Jan 14;172(1):180–183. doi: 10.1016/0005-2728(69)90105-4. [DOI] [PubMed] [Google Scholar]
  28. Sauer K., Biggins J. Action spectra and quantum yields for nicotinamide--adenine dinucleotide phosphate reduction by chloroplasts. Biochim Biophys Acta. 1965 May 25;102(1):55–72. doi: 10.1016/0926-6585(65)90202-5. [DOI] [PubMed] [Google Scholar]
  29. TAGAWA K., TSUJIMOTO H. Y., ARNON D. I. SEPARATION BY MONOCHROMATIC LIGHT OF PHOTOSYNTHETIC PHOSPHORYLATION FROM OXYGEN EVOLUTION. Proc Natl Acad Sci U S A. 1963 Sep;50:544–549. doi: 10.1073/pnas.50.3.544. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES