Article
Light-induced absorption spectra of the D1–D2–cytochrome b 559 complex of Photosystem II: Effect of methyl viologen concentration
Author/s | Yruela Guerrero, Inmaculada
Torrado, Elena Roncel Gil, Mercedes Picorel Castaño, Rafael |
Department | Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular |
Publication Date | 2001 |
Deposit Date | 2019-03-29 |
Published in |
|
Abstract | 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. |
Project ID. | PB98-1632 |
Citation | 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. |
Files | Size | Format | View | Description |
---|---|---|---|---|
LIGHT-INDUCED ABSORPTION SPECT ... | 313.9Kb | [PDF] | View/ | |