title: Thermal stability and redox properties of M. tuberculosis CuSOD.
abstract: The superoxide dismutase from Mycobacterium tuberculosis is the only Cu-containing superoxide dismutase that lacks zinc in the active site. To explore the structural properties of this unusual enzyme, we have investigated its stability by differential scanning calorimetry. We have found that the holo-enzyme is significantly more stable than the apo-protein or the partially metallated enzyme, but that its melting temperature is markedly lower than that of all the other characterized eukaryotic and prokaryotic Cu,Zn superoxide dismutases. We have also observed that, unlike the zinc-free eukaryotic or bacterial enzymes, the active site copper of the mycobacterial enzyme is not reduced by ascorbate, confirming that its redox properties are comparable to those typical of the enzymes containing zinc in the active site. Our findings highlight the role of zinc in conferring stability to Cu,Zn superoxide dismutases and indicate that the structural rearrangements observed in M. tuberculosis Cu,SOD compensate for the absence of zinc in achieving a fully active enzyme.
authors.affiliation: Department of Biology, University of Rome "Tor Vergata", Italy.
authors.forename: Melania
authors.initials: M
authors.lastname: D'Orazio
authors.forename: Laura
authors.initials: L
authors.lastname: Cervoni
authors.forename: Anna
authors.initials: A
authors.lastname: Giartosio
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rotilio
authors.forename: Andrea
authors.initials: A
authors.lastname: Battistoni
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D003300:Copper / Q000032:analysis / Q000378:metabolism; D019281:Dimerization; D004355:Drug Stability; D007700:Kinetics; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D010084:Oxidation-Reduction; D011489:Protein Denaturation; D017510:Protein Folding; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D003300:Copper; D013482:Superoxide Dismutase