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Fe-heme structure in Cu,Zn superoxide dismutase from Haemophilus ducreyi by X-ray Absorption Spectroscopy |
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| Authors: | Paola D’Angelo Andrea Zitolo Giordano Mancini Jean Louis Hazemann Andrea Battistoni |
| Institution: | a Department of Chemistry University “La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy b Department of Biology University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy c CASPUR, Consortium for Supercomputing. Applications, Via dei Tizii 6b, 00185 Rome, Italy d Observatoire des Sciences de l’Univers de Grenoble, UMS CNRS, Université Joseph Fourier, 414, rue de la Piscine, Domaine Universitaire, BP 53, F-38041 Saint-Martin-D’Hères, France e Institut Néél, UPR2940, CNRS, 25 Avenue des Martyrs, BP 166, F-38042 Grenoble codex 9, France |
| Abstract: | We have carried out an X-ray Absorption Spectroscopy (XAS) study of ferric, ferrous, CO- and NO-bound Haemophilus ducreyi Cu,ZnSOD (HdSOD) in solution to investigate the structural modifications induced by the binding of small gaseous ligands to heme in this enzyme. The combined analysis of EXAFS and XANES data has allowed us to characterize the local structure around the Fe-heme with 0.02 Å accuracy, revealing a heterogeneity in the distances between iron and the two histidine ligands which was not evident in the X-ray crystal structure. In addition, we have shown that the metal oxidation state does not influence the Fe-heme coordination environment, whereas the presence of the CO and NO ligands induces local structural rearrangements in the enzyme which are very similar to those already observed in other hexa-coordinated heme proteins, such as neuroglobin. |
| Keywords: | Hemeproteins EXAFS XANES Superoxide dismutase Synchrotron radiation |
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