Structure of a superoxide dismutase and implications for copper-ion chelation.
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.
Yogavel
Manickam
M
Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Road, New Delhi 110 067, India.
Mishra
Prakash Chandra
PC
Gill
Jasmita
J
Bhardwaj
Pardeep Kumar
PK
Dutt
Som
S
Kumar
Sanjay
S
Ahuja
Paramvir Singh
PS
Sharma
Amit
A
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
D002412:Cations; D010940:Plant Proteins; D014867:Water; D003300:Copper; D013482:Superoxide Dismutase