title: On the coordination and oxidation states of the active-site copper ion in prokaryotic Cu,Zn superoxide dismutases.
abstract: The active-site copper ion of the prokaryotic Cu,Zn superoxide dismutase from P. leiognathi is found to undergo reversible reduction upon irradiation of the protein solution with a high-intensity X-ray beam from a third-generation synchrotron source. The same phenomenon is observed for the enzyme crystals, whose diffraction pattern has been obtained from synchrotron sources. In this case the active-site copper-ligand coordination bond lengths and in particular the Cu-NE2(His61) distance are consistent with a copper ion in the reduced state. These results are in line with previous studies on the eukaryotic Cu,Zn superoxide dismutases and suggest the conservation of an identical catalytic mechanism in both the prokaryotic and eukaryotic enzymes.
authors.affiliation: INFM, Dipartimento di Biologia, Università di Roma, Tor Vergata, Italy.
authors.forename: M E
authors.initials: ME
authors.lastname: Stroppolo
authors.forename: S
authors.initials: S
authors.lastname: Nuzzo
authors.forename: A
authors.initials: A
authors.lastname: Pesce
authors.forename: C
authors.initials: C
authors.lastname: Rosano
authors.forename: A
authors.initials: A
authors.lastname: Battistoni
authors.forename: M
authors.initials: M
authors.lastname: Bolognesi
authors.forename: S
authors.initials: S
authors.lastname: Mobilio
authors.forename: A
authors.initials: A
authors.lastname: Desideri
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003300:Copper / Q000737:chemistry; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology; D005057:Eukaryotic Cells; D008024:Ligands; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010776:Photobacterium / Q000201:enzymology*; D010777:Photochemistry; D011387:Prokaryotic Cells; D011487:Protein Conformation; D013057:Spectrum Analysis; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000528:radiation effects; D014965:X-Rays
chemical_list: D008024:Ligands; D003300:Copper; D013482:Superoxide Dismutase