Theoretical study on OH{sup −} site and electronic spin state of oxygen-evolving complex in photosystem II at the dark S{sub 1} state

Journal Article · Tue Dec 10 04:00:00 EST 2013 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4848091· OSTI ID:22261741

Hatakeyama, Makoto; Ogata, Koji; Nakamura, Shinichiro ^[1]; Uchida, Waka ^[2]

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1. RIKEN Research Cluster for Innovation, Nakamura Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
2. Department of Biomolecular Engineering, Tokyo Institute of Technology, B-70, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

Possible protonation and electronic-spin states of oxygen-evolving complex (OEC) in photosystem II have been investigated by using QM(DFT-UB3LYP)/MM(Amber) calculation, in order to elucidate which OEC state satisfies the known experimental results at the dark stable state (S{sub 1}), i.e. OEC involves Mn{sub 4}(III{sub 2},IV{sub 4})-cluster and a S=0 state as the lowest energy electronic-spin state at S{sub 1}. The configuration of Mn oxidation numbers and the lowest energy spin state within the Mn{sub 4}-cluster depend on the protonation state of one oxo-anion bridging three Mn ions. When all water-ligands and oxo-bridges form H{sub 2}O and O{sup 2−}, respectively, the resulting OEC model involved Mn{sub 4}(III{sub 2},IV{sub 2})-cluster and one S=0 state as the lowest energy spin state. To rationalize the O{sup 2−}-bridge model at S{sub 1} state, a new H{sup +}-release scheme during the H{sub 2}O-splitting reaction is proposed.

• OSTI ID: 22261741
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1568; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ANIONS
COMPLEXES
LIGANDS
MANGANESE IONS
OXIDATION
OXYGEN
SPIN