1hau: Difference between revisions

Copper-containing nitrite reductases possess a trimeric structure where, the catalytic Cu site, located at the monomer-monomer interface, resembles, the catalytic sites of a number of Zn enzymes. Nitrite reductase from, Alcaligenes xylosoxidans has optimum activity at pH 5.2 which decreases to, a negligible level at pH 8. The structure of this nitrite reductase has, previously been determined at pH 4.6. It has now been crystallized under, new conditions at pH 8.5. Its crystallographic structure provides a, structural explanation for the greatly reduced activity of the enzyme at, high pH. Characterization of overexpressed protein in solution by EXAFS, suggested that the protein lacked Cu in the catalytic type 2 Cu site and, that the site was most probably occupied by Zn. Using the anomalous, signals from Cu and Zn, the crystal structure revealed that the expressed, protein was devoid of Cu in the catalytic site and that only a trace, amount (<10%) of Zn was present at this site in the crystal. Despite the, close structural similarity of the catalytic site to a number of Zn, enzymes, these data suggest that Zn, if it binds at the catalytic copper, site, binds weakly in nitrite reductase.

1HAU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Achromobacter_xylosoxidans Achromobacter xylosoxidans] with CU as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Transferred_entry:_1.7.2.1 Transferred entry: 1.7.2.1], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.7.99.3 1.7.99.3] Structure known Active Sites: CUA and CUB. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1HAU OCA].  

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov  5 12:41:19 2007''