Artículo
Protein Dynamics Control of Electron Transfer in Photosynthetic Reaction Centers from Rps. Sulfoviridis
Autor/es | Medvedev, E. S.
Kotelnikov, A. I. Barinov, A. V. Psikha, B. L. Ortega Rodríguez, José María |
Departamento | Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular |
Fecha de publicación | 2008 |
Fecha de depósito | 2018-09-20 |
Publicado en |
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Resumen | In the cycle of photosynthetic reaction centers, the initially oxidized special pair of bacteriochlorophyll molecules is subsequently reduced by an electron transferred over a chain of four hemes of the complex. Here, we ... In the cycle of photosynthetic reaction centers, the initially oxidized special pair of bacteriochlorophyll molecules is subsequently reduced by an electron transferred over a chain of four hemes of the complex. Here, we examine the kinetics of electron transfer between the proximal heme c-559 of the chain and the oxidized special pair in the reaction center from Rps. sulfoviridis in the range of temperatures from 294 to 40 K. The experimental data were obtained for three redox states of the reaction center, in which one, two, or three nearest hemes of the chain are reduced prior to special pair oxidation. The experimental kinetic data are analyzed in terms of a Sumi–Marcus-type model developed in our previous paper,1 in which similar measurements were reported on the reaction centers from Rps. viridis. The model allows us to establish a connection between the observed nonexponential electron-transfer kinetics and the local structural relaxation dynamics of the reaction center protein on the microsecond time scale. The activation energy for relaxation dynamics of the protein medium has been found to be around 0.1 eV for all three redox states, which is in contrast to a value around 0.4–0.6 eV in Rps. viridis.1 The possible nature of the difference between the reaction centers from Rps. viridis and Rps. sulfoviridis, which are believed to be very similar, is discussed. The role of the protein glass transition at low temperatures and that of internal water molecules in the process are analyzed. |
Agencias financiadoras | Ministerio de Educación y Ciencia (MEC). España Junta de Andalucía |
Identificador del proyecto | BFU2004-04914-C02-01/BMC
PAI CVI-261 |
Cita | Medvedev, E.S., Kotelnikov, A.I., Barinov, A.V., Psikha, B.L. y Ortega Rodríguez, J.M. (2008). Protein Dynamics Control of Electron Transfer in Photosynthetic Reaction Centers from Rps. Sulfoviridis. Journal of Physical Chemistry B, 112 (10), 3208-3216. |
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