1huh

DIFFERENCES IN ANIONIC INHIBITION OF HUMAN CARBONIC ANHYDRASE I REVEALED FROM THE STRUCTURES OF IODIDE AND GOLD CYANIDE INHIBITOR COMPLEXES

spinqualitylabelsall models 1huh, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1huh is a 1 chain structure with sequence from Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: IOD, ZN Activity: Carbonate dehydratase, with EC number 4.2.1.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [CAH1_HUMAN] Reversible hydration of carbon dioxide. Can hydrates cyanamide to urea. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The crystal structures of two anionic inhibitor complexes of human carbonic anhydrase I (HCAI), namely, HCAI-iodide and HCAI-Au(CN)(2)(-), have been refined by the restrained least-squares method at 2.2 and 2 A nominal resolution, respectively, with good stereochemistry for the final models. The R values have improved from 30.3 to 16.6% for HCAI-iodide and from 28.8 to 17.1% for HCAI-Au(CN)(2)(-). The sites of inhibitor binding as elucidated are totally different in the two structures. The iodide anion replaces the zinc-bound H(2)O/OH(-) ligand and renders the enzyme inactive. This result confirms that the zinc-bound H(2)O/OH(-) is the activity-linked group in carbonic anhydrase enzymes. Au(CN)(2)(-) binds at a different and new site near the zinc ion, without liganding to the metal. The N atom of Au(CN)(2)(-) is within hydrogen-bonding distance of the zinc-bound H(2)O/OH(-) group which shifts by about 0.4 A away from the zinc ion in relation to its position in the native HCAI. It is proposed that the presence of the inhibitor Au(CN)(2)(-) results in a conformational reorientation of the activity-linked group, due to hydrogen-bond formation with the inhibitor, which in turn sterically hinders the binding of the substrate CO(2) molecule in the active site, leading to the inhibition of HCAI enzyme. Differences in anionic inhibition of human carbonic anhydrase I revealed from the structures of iodide and gold cyanide inhibitor complexes.,Kumar V, Kannan KK, Sathyamurthi P Acta Crystallogr D Biol Crystallogr. 1994 Sep 1;50(Pt 5):731-8. PMID:15299369 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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