Funding Organization(s): National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS), Department of Energy (DOE, United States)
The dioxygen we breathe is formed by light-induced oxidation of water in photosystem II. O2 formation takes place at a catalytic manganese cluster within milliseconds after the photosystem II reaction centre is excited by three single-turnover flashes. Here we present combined X-ray emission spectra and diffraction data of 2-flash (2F) and 3-flash (3F) photosystem II samples, and of a transient 3F' state (250 μs after the third flash), collected under functional conditions using an X-ray free electron laser. The spectra show that the initial O-O bond formation, coupled to Mn reduction, does not yet occur within 250 μs after the third flash. Diffraction data of all states studied exhibit an anomalous scattering signal from Mn but show no significant structural changes at the present resolution of 4.5 Å. This study represents the initial frames in a molecular movie of the structural changes during the catalytic reaction in photosystem II.
Organizational Affiliation:
1] Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
1] Institut für Biologie, Humboldt-Universität zu Berlin, D-10099 Berlin, Germany [2] Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität, D-10623 Berlin, Germany.
PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
1] Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2].
Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität, D-10623 Berlin, Germany.
1] LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA [2].
European Synchrotron Radiation Facility, F-38043 Grenoble, France.
SSRL, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
1] LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA [2] PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
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