title: Do the higher oxidation states of the photosynthetic O2-evolving system contain bound H2O?
abstract: A modified mass spectrometer was used to determine whether the higher oxidation states of the photosynthetic O2-evolving system contain substrate water that is not freely exchangeable with the external medium.  Our data indicated that the higher oxidation states contain no appreciable bound, non-exchangeable H2O.  This suggests that H2O oxidation takes place via a rapid, concerted, all-or-none mechanism rather than by a mechanism involving stable, partially oxidized, H2O-derived intermediates.  These findings set definite constraints on possible mechanisms of O2 evolution.
authors.affiliation: Martin Marietta Laboratories, Baltimore, MD 21227, USA.
authors.forename: R
authors.initials: R
authors.lastname: Radmer
authors.forename: O
authors.initials: O
authors.lastname: Ollinger
mesh_terms: D002736:Chloroplasts / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D013058:Mass Spectrometry; D010100:Oxygen / Q000737:chemistry*; D010103:Oxygen Isotopes; D018462:Photobiology; D010788:Photosynthesis / Q000502:physiology*; D014867:Water / Q000737:chemistry*
chemical_list: D010103:Oxygen Isotopes; D014867:Water; D010100:Oxygen