title: Photoinactivation of photosystem II by flashing light.
abstract: Inhibition of Photosystem II (PS II) activity by single turnover visible light flashes was studied in thylakoid membranes isolated form spinach. Flash illumination results in decreased oxygen evolving activity of PS II, which effect is most pronounced when the water-oxidizing complex is in the S2 and S3 states, and increases with increasing time delay between the subsequent flashes. By applying the fluorescent spin-trap DanePy, we detected the production of singlet oxygen, whose amount was increasing with increasing flash spacing. These findings were explained in the framework of a model, which assumes that recombination of the S2QB - and S3QB - states generate the triplet state of the reaction center chlorophyll and lead to the production of singlet oxygen.
authors.affiliation: Institute of Plant Biology, Biological Research Center of the Hungarian Academy of Sciences, P.O. Box 521, 6701 Szeged, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Szilárd
authors.forename: László
authors.initials: L
authors.lastname: Sass
authors.forename: Eva
authors.initials: E
authors.lastname: Hideg
authors.forename: Imre
authors.initials: I
authors.lastname: Vass
mesh_terms: D008027:Light; D045332:Photosystem II Protein Complex / Q000378:metabolism / Q000528:radiation effects*; D026082:Singlet Oxygen / Q000378:metabolism; D018724:Spinacia oleracea; D020524:Thylakoids / Q000378:metabolism / Q000528:radiation effects; D013997:Time Factors
chemical_list: D045332:Photosystem II Protein Complex; D026082:Singlet Oxygen