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PDBsum entry 1bic

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Lyase(oxo-acid) PDB id
1bic
Jmol
Contents
Protein chain
258 a.a.
Ligands
BCT
MMC
Metals
_ZN
Waters ×208

References listed in PDB file
Key reference
Title Crystallographic analysis of thr-200-->His human carbonic anhydrase ii and its complex with the substrate, Hco3-.
Authors Y.Xue, J.Vidgren, L.A.Svensson, A.Liljas, B.H.Jonsson, S.Lindskog.
Ref. Proteins, 1993, 15, 80-87.
PubMed id 8451242
Abstract
A complex of carbonic anhydrase (CA) with one of its substrates, bicarbonate, has been studied crystallographically. Human isoenzyme II was mutated at position 200 from threonine to histidine, which results in higher affinity for bicarbonate. The HCO3- ion binds in the active site to the zinc ion as a pseudo-bidentate ligand which gives the metal a coordination geometry between tetrahedral and trigonal bipyramide. The water/hydroxide normally bound with tetrahedral coordination to the zinc is probably replaced by the OH group of the bicarbonate ion. The importance of residues Thr-199 and Glu-106 in controlling the binding orientation of HCO3- is discussed as well as the catalytic mechanism. Both the complex as well as the uncomplexed mutant were studied at 1.9 A resolution.
PROCHECK
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