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dc.contributor.authorYruela Guerrero, Inmaculada-
dc.contributor.authorMontoya Blanco, Guillermo-
dc.contributor.authorAlonso, Pablo J.-
dc.identifier.citationJournal of Biological Chemistry 266: 22847- 22850 (1991)-
dc.description.abstractOxygen evolution by photosystem II membranes was inhibited by Cu(II) when 2,6-dichlorobenzoquinone or ferricyanide, but not silicomolybdate, was used as electron acceptor. This indicated that Cu(II) affected the reducing side of the photosystem II. The inhibition curves of Cu(II), o-phenanthroline and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), were compared; the inhibitory patterns of Cu(II) and o-phenanthroline were very similar and different in turn from that of DCMU. Cu(II) did not eliminate or modify the electron paramagnetic resonance signal at g = 8.1 ascribed to the non-heme iron of the photosystem II reaction center, indicating that the inhibition by Cu(II) was not the result of the replacement of the iron by Cu(II). Controlled trypsin digestion of thylakoid membranes inhibited oxygen evolution using 2,6-dichlorobenzoquinone, but had no effect when using ferricyanide or silicomolybdate. Using ferricyanide, oxygen evolution of trypsin-treated thylakoids was insensitive to DCMU but became even more sensitive to Cu(II) and o-phenanthroline than nontreated thylakoids; however, trypsinized thylakoids were insensitive to inhibitors in the presence of silicomolybdate. We conclude that Cu(II) impaired the photosystem II electron transfer before the Q(B) niche, most probably at the pheophytin-Q(A)-Fe domain.-
dc.description.sponsorshipThis work was supported by the Direccion General de Investigacion Cientifica y Tecnica (DGICYT, Grant PB89-0060 to R. P.) and Consejo Asesor de Investigacion-Diputacion General de Aragon (CONAI-DGA, Grant P CB3-89 to R. P.). . Yruela I is Recipient of postdoctoral fellowships from the Consejo Superior de Investigaciones Cientificas (CSIC), Spain. Montoya G is Recipient of a doctoral fellowship from the Consejo Asesor de Investigacion-Diputacion General de Aragon, Spain.-
dc.publisherAmerican Society for Biochemistry and Molecular Biology-
dc.titleIdentification of the pheophytin-Q(A)-Fe domain of the reducing side of the photosystem II as the Cu(II)-inhibitory binding site-
dc.description.versionPeer Reviewed-
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