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Most ultrafast transient absorption studies of primary electron transfer in reaction centers from purple bacteria have been performed in complexes isolated from their natural lipid membrane environment using detergent. In this contribution we present near-UV-vis transient absorption studies of reaction centers embedded in their natural membrane environment. The evolution of absorption spectra recorded with subpicosecond resolution and reflecting primarily electron transfer reactions has been compared to data obtained previously for isolated reaction centers. We conclude that the overall spectral evolution in both types of samples is similar, and the environment of the reaction center protein has only a minor effect on the primary electron transfer reactions. The differences between the two samples are explained in terms of different energetic levels (and their different temporal evolution) of the two initial charge separated states P+BA- and P+HA-, with P being the primary electron donor and B-A and H-A the two consecutive electron acceptors. Additionally, in the electric field generated by. P+HA-, B-A in membrane-bound reaction centers undergoes a stronger electrochromic shift than in isolated reaction centers.
|Number of pages||6|
|Journal||Acta Physica Polonica A|
|Publication status||Published - Aug 2012|