title: Structure of a superoxide dismutase and implications for copper-ion chelation.
abstract: Superoxide dismutase (SOD) plays a central role in cellular defence against oxidative stress and is of pharmaceutical importance. The SOD from Potentilla atrosanguinea (Pa-SOD) is a unique enzyme as it possesses free-radical scavenging capability at temperatures ranging between 263 and 353 K. The crystal structure of recombinant Pa-SOD has been determined to 2.3 A resolution. The active-site residues are well ordered and additional water molecules are present in place of a bound copper ion. There is a significant difference in the relative orientation of the two subunits of Pa-SOD and asymmetry is also present in numerous hydrogen-bonding interactions. Structures of SODs, both bound with copper and unbound, have been compared with respect to the orientation of the electrostatic and Greek-key loops. This analysis provides new insights into the copper-chelation process in SODs. Several new structural features in Pa-SOD which may be responsible for its unique properties of thermostability and expanded range of antioxidant activity are also highlighted.
authors.affiliation: Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Road, New Delhi 110 067, India.
authors.forename: Manickam
authors.initials: M
authors.lastname: Yogavel
authors.forename: Prakash Chandra
authors.initials: PC
authors.lastname: Mishra
authors.forename: Jasmita
authors.initials: J
authors.lastname: Gill
authors.forename: Pardeep Kumar
authors.initials: PK
authors.lastname: Bhardwaj
authors.forename: Som
authors.initials: S
authors.lastname: Dutt
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kumar
authors.forename: Paramvir Singh
authors.initials: PS
authors.lastname: Ahuja
authors.forename: Amit
authors.initials: A
authors.lastname: Sharma
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002412:Cations / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019281:Dimerization; D004795:Enzyme Stability; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry*; D031987:Potentilla / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D013482:Superoxide Dismutase / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D002412:Cations; D010940:Plant Proteins; D014867:Water; D003300:Copper; D013482:Superoxide Dismutase