PDBsum entry 1i6o

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Lyase PDB id
Protein chains
213 a.a. *
_ZN ×2
Waters ×87
* Residue conservation analysis

References listed in PDB file
Key reference
Title Crystal structure of e. Coli beta-Carbonic anhydrase, An enzyme with an unusual ph-Dependent activity.
Authors J.D.Cronk, J.A.Endrizzi, M.R.Cronk, J.W.O'Neill, K.Y.Zhang.
Ref. Protein Sci, 2001, 10, 911-922.
PubMed id 11316870
Carbonic anhydrases fall into three distinct evolutionary and structural classes: alpha, beta, and gamma. The beta-class carbonic anhydrases (beta-CAs) are widely distributed among higher plants, simple eukaryotes, eubacteria, and archaea. We have determined the crystal structure of ECCA, a beta-CA from Escherichia coli, to a resolution of 2.0 A. In agreement with the structure of the beta-CA from the chloroplast of the red alga Porphyridium purpureum, the active-site zinc in ECCA is tetrahedrally coordinated by the side chains of four conserved residues. These results confirm the observation of a unique pattern of zinc ligation in at least some beta-CAS: The absence of a water molecule in the inner coordination sphere is inconsistent with known mechanisms of CA activity. ECCA activity is highly pH-dependent in the physiological range, and its expression in yeast complements an oxygen-sensitive phenotype displayed by a beta-CA-deletion strain. The structural and biochemical characterizations of ECCA presented here and the comparisons with other beta-CA structures suggest that ECCA can adopt two distinct conformations displaying widely divergent catalytic rates.
Secondary reference #1
Title Cloning, Crystallization and preliminary characterization of a beta-Carbonic anhydrase from escherichia coli.
Authors J.D.Cronk, J.W.O'Neill, M.R.Cronk, J.A.Endrizzi, K.Y.Zhang.
Ref. Acta Crystallogr D Biol Crystallogr, 2000, 56, 1176-1179. [DOI no: 10.1107/S0907444900008519]
PubMed id 10957638
Full text Abstract
Figure 1.
Figure 1 Three CynT2 crystal forms. (a) Form 1 crystals grown from 1.8 M (NH[4])[2]SO[4], 0.1 M MES pH 6.15. Typical crystal dimensions are 0.4 0.5 0.8 mm. The protein concentration is approximately 12 mg ml-1. (b) Form 2 crystals grown from conditions similar to those producing form 1, except for the addition of PEG 400 to 4% final concentration. Typical crystal dimensions are 0.25 0.3 0.6 mm. (c) Form 2 crystals of selenomethionine-substituted CynT2 grown from the same condition that produced form 2 native CynT2 crystals. Typical crystal dimensions are 0.3 0.4 0.75 mm.
The above figure is reproduced from the cited reference with permission from the IUCr
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