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Peariso K, Zhou ZS, Smith AE, Matthews RG, Penner-Hahn JE (2001) Biochemistry 40:987–993 Special issue on BioXAS (2003) J Synchrotron Rad 10(1)ĭau H, Dittmer J, Epple M, Hanss J, Kiss E, Rehder D, Schultze C, Vilter H (1999) FEBS Lett 457:237–240 University Science Books, Sausalito, pp 465–504ĭau H, Haumann M (2003) J Synchrotron Rad 10:76–85 Scott RA (2000) In: Que L (ed) Physical methods in bioinorganic chemistry-spectroscopy and magnetism. George GN, Hedman B, Hodgson KO (1998) Nature Struc Biol-Synchrotron Supplement:645–647 Hill HAO, Sadler PJ, Thomson AJ (1999) Metal sites in proteins and models. University Science Books, SausalitoĬowan JA (1996) Inorganic biochemistry: an introduction. Lippard SJ, Berg JM (1994) Principles of bioinorganic chemistry. Furthermore, the potential of modern XANES theory is demonstrated by presenting first simulations of the dichroism in the XANES spectra of the PSII manganese complex.
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(3) The underlying reasons for the oxidation-state dependence of the XANES spectra are explored. (2) The interpretation of XANES spectra in terms of molecular orbitals (MOs) is approached by comparative multiple-scattering calculations and MO calculations.
RAY GEOMETRY SERIES
In the XANES section the following aspects are considered: (1) Alternative approaches are evaluated for determination of the metal-oxidation state by comparison with a series of model compounds. Subsequently, the method of linear dichroism EXAFS spectroscopy is introduced and it is shown how the EXAFS data leads to an atomic resolution model for the tetra-manganese complex of PSII. The EXAFS section starts with an exemplifying discussion of a PSII spectrum data set with focus on the coordination number problem. For first-sphere ligands and second-sphere metals (in multinuclear complexes), the determination of precise distances is mostly straightforward, whereas the determination of coordination numbers clearly requires more effort. The EXAFS range carries direct information on the number and distances of ligands as well as on the chemical type of the ligand donor function. In the present study the information content of X-ray spectra with respect to the nuclear geometry and, in particular, to the electronic structure of the protein-bound metal ions is explored using the manganese complex of photosystem II (PSIII) as a model system. X-ray absorption spectroscopy (XAS) has become a prominent tool for the element-specific analysis of transition metals at the catalytic center of metalloenzymes.