English   español  
Por favor, use este identificador para citar o enlazar a este item: http://hdl.handle.net/10261/11083
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Exportar a otros formatos:

Copper(II) inhibition of electron transfer through photosystem II studied by EPR spectroscopy.

AutorJegerschöld, Caroline; Arellano, Juan B. ; Schröder, Wolfgang P.; van Kan, Paul J. M.; Barón Ayala, Matilde; Styring, Stenbjörn
Palabras claveCopper
Photosystem II
Electron Spin Resonance
Fecha de publicaciónoct-1995
EditorAmerican Chemical Society
CitaciónBiochemistry (2005) 34 : 12747-54
ResumenEPR spectroscopy was applied to investigate the inhibition of electron transport in photosystem II by Cu2+ ions. Our results show that Cu2+ has inhibitory effects on both the donor and the acceptor side of photosystem II. In the presence of Cu2+, neither EPR signal IIvery fast nor signal IIfast, which both reflect oxidation of tyrosinez, could be induced by illumination. This shows that Cu2+ inhibits electron transfer from tyrosinez to the oxidized primary donor P680+. Instead of tyrosinez oxidation, illumination results in the formation of a new radical with g = 2.0028 +/- 0.0002 and a spectral width of 9.5 +/- 0.3 G. At room temperature, this radical amounts to one spin per PS II reaction center. Incubation of photosystem II membranes with cupric ions also results in release of the 16 kDa extrinsic subunit and conversion of cytochrome b559 to the low-potential form. On the acceptor side, QA can still be reduced by illumination or chemical reduction with dithionite. However, incubation with Cu2+ results in loss of the normal EPR signal from QA- which is coupled to the non-heme Fe2+ on the acceptor side (the QA(-)-Fe2+ EPR signal). Instead, reduction of QA results in the formation of a free radical spectrum which is 9.5 G wide and centered at g = 2.0044. This signal is attributed to QA- which is magnetically decoupled from the non-heme iron. This suggests that Cu2+ displaces the Fe2+ or severely alters its binding properties. The inhibition of tyrosinez is reversible upon removal of the copper ions with EDTA while the modification of QA was found to be irreversible.
Versión del editorhttp://pubs.acs.org/doi/abs/10.1021/bi00039a034
Aparece en las colecciones: (IRNASA) Artículos
Ficheros en este ítem:
Fichero Descripción Tamaño Formato  
Jegerschöld et al 1995.pdf174,68 kBAdobe PDFVista previa
Mostrar el registro completo

Artículos relacionados:

NOTA: Los ítems de Digital.CSIC están protegidos por copyright, con todos los derechos reservados, a menos que se indique lo contrario.