title: Strong Coupling between the Hydrogen Bonding Environment and Redox Chemistry during the S2 to S3 Transition in the Oxygen-Evolving Complex of Photosystem II.
abstract: We have studied the early phase of the S2 → S3 transition in the oxygen-evolving complex (OEC) of photosystem II using the hybrid density functional theory with a quantum mechanical model composed of 338-341 atoms. Special attention is given to the vital role of water molecules in the vicinity of the Mn4CaO5 core. Our results demonstrate how important the dynamic behavior of surrounding water molecules is in mediating critical chemical transformations such as binding and deprotonation of substrates and hydration of the catalytic site and identify a strong coupling of water-chain relocation near the redox-active tyrosine residue Tyr161 (TyrZ) with oxidation of the Mn4CaO5 cluster by TyrZ(•+). The oxidation reaction is further promoted when the catalytic site is more solvated by water. These results indicate the importance of surrounding water molecules in biological catalysts as they ultimately lead to effective catalytic function and/or favorable electron-transfer dynamics.
authors.affiliation: Photosynthesis Research Center, Graduate School of Natural Science and Technology, Okayama University , Okayama 700-8530, Japan.|The Institute of Scientific and Industrial Research, Osaka University , Ibaraki, Osaka 567-0047, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Isobe
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8577, Japan.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Shoji
authors.affiliation: Photosynthesis Research Center, Graduate School of Natural Science and Technology, Okayama University , Okayama 700-8530, Japan.
authors.forename: Jian-Ren
authors.initials: JR
authors.lastname: Shen
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University , Ibaraki, Osaka 567-0047, Japan.|Institute for NanoScience Design, Osaka University , Toyonaka, Osaka 560-0043, Japan.
authors.forename: Kizashi
authors.initials: K
authors.lastname: Yamaguchi
mesh_terms: D004579:Electron Transport; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism*; D011789:Quantum Theory
chemical_list: D045332:Photosystem II Protein Complex; D010100:Oxygen