Photosynthetic water oxidation at high O-2 backpressure monitored by delayed chlorophyll fluorescence
Autor(en): | Clausen, J Junge, W Dau, H Haumann, M |
Stichwörter: | Biochemistry & Molecular Biology; CLUSTER; COMPLEX; DEPENDENCE; II MEMBRANE-PARTICLES; OXYGEN EVOLUTION; PHOTOSYSTEM-II; SPECTROSCOPY; SPINACH; TEMPERATURE | Erscheinungsdatum: | 2005 | Herausgeber: | AMER CHEMICAL SOC | Journal: | BIOCHEMISTRY | Volumen: | 44 | Ausgabe: | 38 | Startseite: | 12775 | Seitenende: | 12779 | Zusammenfassung: | The atmospheric dioxygen is produced by photosynthetic organisms. This light-driven process culminates in what appears as one step: a four-electron abstraction from two water molecules bound to the Mn4Ca complex of photosystem II. Recently, an intermediate of the O-2-producing reaction sequence was stabilized by elevated oxygen backpressure and detected by UV flash photometry [Clausen, J., and Junge, W. (2004) Nature 430, 480]. We scrutinized its properties by delayed chlorophyll fluorescence measurements. Half-suppression of oxygen evolution was observed at a similar O-2 pressure of 2.3 bar, as previously, now with photosystem II membrane particles from spinach, without artificial electron acceptors, and at a high signal-to-noise ratio. The data are tentatively interpreted as the stabilization of a 2-fold oxidized state of the catalytic center (S-2*) With bound peroxide and its slow conversion into the normal S-2 state by the release of peroxide. |
ISSN: | 00062960 | DOI: | 10.1021/bi051183a |
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geprüft am 01.06.2024