Fe-heme structure in Cu,Zn superoxide dismutase from Haemophilus ducreyi by X-ray Absorption Spectroscopy

Paola D’angelo (1) , Andrea Zitolo (2, 1) , Francesca Pacello (3) , Giordano Mancini (4, 5) , Olivier Proux (6) , Jean-Louis F Hazemann (7) , Alessandro Desideri (3) , Andrea Battistoni (3)

1 UNIROMA - Università degli Studi di Roma "La Sapienza" = Sapienza University [Rome]
2 SSOLEIL - Synchrotron SOLEIL
3 Università degli Studi di Roma Tor Vergata [Roma] = University of Rome Tor Vergata
4 Ist Nazl Fis Nucl, Sez Pisa, Pisa, Italy
5 CASPUR
6 OSUG - Observatoire des Sciences de l'Univers de Grenoble
7 NEEL - MRS - Matériaux, Rayonnements, Structure

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.

Domaines: Instrumentations et Détecteurs [physics.ins-det]

Paola D’angelo, Andrea Zitolo, Francesca Pacello, Giordano Mancini, Olivier Proux, et al.. Fe-heme structure in Cu,Zn superoxide dismutase from Haemophilus ducreyi by X-ray Absorption Spectroscopy. Archives of Biochemistry and Biophysics, 2010, 498 (1), pp.43-49. ⟨10.1016/j.abb.2010.03.010⟩. ⟨hal-02175803⟩