Crystal structure of nickel-containing superoxide dismutase reveals another type of active site
AUTOR(ES)
Wuerges, Jochen
FONTE
National Academy of Sciences
RESUMO
Superoxide dismutases (SODs, EC 1.15.1.1) 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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=423235Documentos Relacionados
- Three-dimensional structure of the nickel-containing hydrogenase from Thiocapsa roseopersicina.
- Nickel affects expression of the nickel-containing hydrogenase of Alcaligenes latus.
- Nickel-containing factor F430: chromophore of the methylreductase of Methanobacterium.
- Some properties of the nickel-containing hydrogenase of chemolithotrophically grown Rhizobium japonicum.
- Nickel-containing hydrogenase isoenzymes from anaerobically grown Escherichia coli K-12.