Send to:

Choose Destination
See comment in PubMed Commons below
Proc Natl Acad Sci U S A. 2004 Jun 8;101(23):8569-74. Epub 2004 Jun 1.

Crystal structure of nickel-containing superoxide dismutase reveals another type of active site.

Author information

  • 1International School for Advanced Studies, Via Beirut 2-4, I-34014 Trieste, Italy.


Superoxide dismutases (SODs, EC are ubiquitous enzymes that efficiently catalyze the dismutation of superoxide radical anions to protect biological molecules from oxidative damage. The crystal structure of nickel-containing SOD (NiSOD) from Streptomyces seoulensis was determined for the resting, x-ray-reduced, and thiosulfate-reduced enzyme state. NiSOD is a homohexamer consisting of four-helix-bundle subunits. The catalytic center resides in the N-terminal active-site loop, where a Ni(III) ion is coordinated by the amino group of His-1, the amide group of Cys-2, two thiolate groups of Cys-2 and Cys-6, and the imidazolate of His-1 as axial ligand that is lost in the chemically reduced state as well as after x-ray-induced reduction. This structure represents a third class of SODs concerning the catalytic metal species, subunit structure, and oligomeric organization. It adds a member to the small number of Ni-metalloenzymes and contributes with its Ni(III) active site to the general understanding of Ni-related biochemistry. NiSOD is shown to occur also in bacteria other than Streptomyces and is predicted to be present in some cyanobacteria.

[PubMed - indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk