1h9q

OverviewOverview

The catalytic zinc ion of human carbonic anhydrase II (CAII) is, coordinated by three histidine ligands (H94, H96, and H119) and a, hydroxide ion with tetrahedral geometry. Structural and functional, analysis of variants in which the zinc ligands H94 and H119 are, substituted with asparagine and glutamine, and comparison with results, obtained with aspartate and glutamate substitutions indicate that the, neutral ligand field provided by the protein optimizes the electrostatic, environment for the catalytic function of the metal ion, including, stabilization of bound anions. This is demonstrated by catalytic activity, measurements for ester hydrolysis and CO2 hydration, as well as, sulfonamide inhibitor affinity assays. High-resolution X-ray crystal, structure determinations of H94N, ... [(full description)]

About this StructureAbout this Structure

1H9Q is a [Single protein] structure of sequence from [Homo sapiens] with ZN as [ligand]. Active as [Carbonate dehydratase], with EC number [4.2.1.1]. Structure known Active Site: ZN. Full crystallographic information is available from [OCA].

ReferenceReference

Histidine --> carboxamide ligand substitutions in the zinc binding site of carbonic anhydrase II alter metal coordination geometry but retain catalytic activity., Lesburg CA, Huang C, Christianson DW, Fierke CA, Biochemistry. 1997 Dec 16;36(50):15780-91. PMID:9398308

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