title: S3 State of the O2-Evolving Complex of Photosystem II: Insights from QM/MM, EXAFS, and Femtosecond X-ray Diffraction.
abstract: The oxygen-evolving complex (OEC) of photosystem II has been studied in the S3 state by electron paramagnetic resonance, extended X-ray absorption fine structure (EXAFS), and femtosecond X-ray diffraction (XRD). However, the actual structure of the OEC in the S3 state has yet to be established. Here, we apply hybrid quantum mechanics/molecular mechanics methods and propose a structural model that is consistent with EXAFS and XRD. The model supports binding of water ligands to the cluster in the S2 → S3 transition through a carousel rearrangement around Mn4, inspired by studies of ammonia binding.
authors: Department of Chemistry and ‡Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06520-8107, United States.
authors: Mikhail
authors: M
authors: Askerka
authors: Department of Chemistry and ‡Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06520-8107, United States.
authors: Jimin
authors: J
authors: Wang
authors: Department of Chemistry and ‡Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06520-8107, United States.
authors: David J
authors: DJ
authors: Vinyard
authors: Department of Chemistry and ‡Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06520-8107, United States.
authors: Gary W
authors: GW
authors: Brudvig
authors: Department of Chemistry and ‡Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06520-8107, United States.
authors: Victor S
authors: VS
authors: Batista
mesh_terms: D001665:Binding Sites; D055162:Biocatalysis; D018360:Crystallography, X-Ray; D005583:Fourier Analysis; D008024:Ligands; D008345:Manganese / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D011789:Quantum Theory; D014867:Water / Q000737:chemistry / Q000378:metabolism; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
chemical_list: D008024:Ligands; D045332:Photosystem II Protein Complex; C064388:oxygen-evolving complex, 33 kDa protein; D014867:Water; D008345:Manganese