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AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.49: Poster

Wednesday, March 29, 2006, 16:30–19:30, P3

Temperature dependence of X-ray photoreduction and EXAFS Debye-Waller factors suggest role of protein-specific dynamics — •Paola Loja — FU-Berlin

In oxygenic photosynthesis, driven by lights the Mn4-complex of Photosystem II (PSII) cycles through four semi-stable intermediate states denoted as S-states. As revealed by X-ray absorption spectroscopy (XAS, EXAFS), the S-state transitions are coupled to significant rearrangements of the nuclei of the tetra-manganese complex (Dau et al., 2000; Haumann et al, 2002). Nonetheless the energetic efficiency is extraordinary high (small enthalpic losses) and the involved activation energies are surprisingly low. Are protein-specific dynamics of importance?