An oscillating manganese electron paramagnetic resonance signal from the S0 state of the oxygen evolving complex in photosystem II

  • Åhrling K
  • Peterson S
  • Styring S
  • 2


    Mendeley users who have this article in their library.
  • 136


    Citations of this article.


Photosynthesis produces the oxygen necessary for all aerobic life. During this process, the manganese-containing oxygen evolving complex (OEC) in photosystem II (PSII), cycles through five oxidation states, S0-S4. One of these, S2, is known to be paramagnetic and gives rise to electron paramagnetic resonance (EPR) signals used to probe the catalytic structure and function of the OEC. The S0 state has long been thought to be paramagnetic. We report here aMn EPR signal from the previously EPR invisible S0 state. The new signal oscillates with a period of four, indicating that it originates from fully active PSII centers. Although similar to the S2 state multiline signal, the new signal is wider (2200 gauss compared with 1850 gauss in samples produced by flashing), with different peak intensity and separation (82 gauss compared with 89 gauss). These characteristics are consistent with the S0 state EPR signal arising from a coupled MnII-MnIII intermediate. The new signal is more stable than the S2 state signal and its decay in tens of minutes is indicative of it originating from the S0 state. The S0 state signal will provide invaluable information toward the understanding of oxygen evolution in plants.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Karin A. Åhrling

  • Sindra Peterson

  • Stenbjörn Styring

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free