Structure of the manganese complex in photosystem II: Insights from X-ray spectroscopy

Vittal K. Yachandra, W. Junge, C. Dismukes, L. Hammarström

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67 Scopus citations


We have used Mn K-edge absorption and Kβ emission spectroscopy to determine the oxidation states of the Mn complex in the various S states. We have started exploring the new technique of resonant inelastic X-ray scattering spectroscopy; this technique can be characterized as a Raman process that uses K-edge energies (1s to 4p, ca. 6550 eV) to obtain L-edge-like spectra (2p to 3d, ca. 650 eV). The relevance of these data to the oxidation states and structure of the Mn complex is presented. We have obtained extended X-ray absorption fine structure data from the S0 and S3 states and observed heterogeneity in the Mn-Mn distances leading us to conclude that there may be three rather than two di-μ-oxo-bridged units present per tetranuclear Mn cluster. In addition, we have obtained data using Ca and Sr X-ray spectroscopy that provide evidence for a heteronuclear Mn-Ca cluster. The possibility of three di-μ-oxo-bridged Mn-Mn moieties and the proximity of Ca is incorporated into developing structural models for the Mn cluster. The involvement of bridging and terminal O ligands of Mn in the mechanism of oxygen evolution is discussed in the context of our X-ray spectroscopy results.

Original languageEnglish (US)
Pages (from-to)1347-1358
Number of pages12
JournalPhilosophical Transactions of the Royal Society B: Biological Sciences
Issue number1426
StatePublished - Oct 29 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)


  • Extended X-ray absorption fine structure
  • Oxygen-evolving complex
  • Photosystem II
  • X-ray absorption near-edge structure
  • X-ray absorption spectroscopy
  • X-ray emission spectroscopy

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