Artículo
Light-induced absorption spectra of the D1–D2–cytochrome b 559 complex of Photosystem II: Effect of methyl viologen concentration
Autor/es | Yruela Guerrero, Inmaculada
Torrado, Elena Roncel Gil, Mercedes Picorel Castaño, Rafael |
Departamento | Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular |
Fecha de publicación | 2001 |
Fecha de depósito | 2019-03-29 |
Publicado en |
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Resumen | The light-induced difference absorption spectra associated to the photo-accumulation of reduced pheophytin a were studied in the isolated D1–D2–Cyt b559 complex in the presence of variable methyl viologen concentrations ... The light-induced difference absorption spectra associated to the photo-accumulation of reduced pheophytin a were studied in the isolated D1–D2–Cyt b559 complex in the presence of variable methyl viologen concentrations and different illumination conditions under anaerobiosis. Depending on the methyl viologen/reaction centre ratio, the relative intensities of the spectral bands at 681.5±0.5, 667.0±0.5 and 542.5±0.5 nm were modified. The reduced pheophytin a located at the D1-branch of the complex absorbs at 681.7±0.5 nm, and at least two additional pigment species contribute to the Qy band of the difference absorption spectra with maxima at 667.0±0.5 and 680.5±0.5 nm. We propose the additional species correspond to a peripheral chlorophyll a and the pheophytin a located at the D2-branch of the complex, respectively. The blue absorbing chlorophyll at 667 nm is susceptible to chemical redox changes with a midpoint reduction potential of +470 mV. The Qx absorption bands of both pheophytins localised at the D2- and D1-branch of the D1–D2–Cyt b559 complex were at 540.7±0.5 and 542.9±0.5, respectively. The results indicated that the two pheophytin molecules can be photoreduced in the D1–D2–Cyt b559 complex in certain experimental conditions. |
Identificador del proyecto | PB98-1632 |
Cita | Yruela Guerrero, I., Torrado, E., Roncel Gil, M. y Picorel Castaño, R. (2001). Light-induced absorption spectra of the D1–D2–cytochrome b 559 complex of Photosystem II: Effect of methyl viologen concentration. Photosynthesis Research, 67 (3), 199-206. |
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