title: X-ray Detection of the Period-Four Cycling of the Manganese Cluster in Photosynthetic Water Oxidizing Enzyme.
abstract: X-ray absorption near-edge structure spectra of the manganese (Mn) cluster in physiologically native intermediate states of photosynthetic water oxidation induced by short laser flash were measured with a compact heat-insulated chamber equipped with an x-ray detector near the sample surface. The half-height energy of the Mn Kedge showed a period-four oscillation dependent on cycling of the Joliot-Kok's oxygen clock. The flash number-dependent shift in the Mn K-edge suggests that the Mn cluster is oxidized by one electron upon the S(0)-to-S(1), S(1)-to-S(2), and S(2)-to-S(3) transitions and then reduced upon the S(3)-to-S(0) transition that releases molecular oxygen.
authors.forename: T A
authors.initials: TA
authors.lastname: Ono
authors.forename: T
authors.initials: T
authors.lastname: Noguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
authors.forename: M
authors.initials: M
authors.lastname: Kusunoki
authors.forename: T
authors.initials: T
authors.lastname: Matsushita
authors.forename: H
authors.initials: H
authors.lastname: Oyanagi