1i6p
From Proteopedia
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CRYSTAL STRUCTURE OF E. COLI BETA CARBONIC ANHYDRASE (ECCA)
Overview
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.
About this Structure
1I6P is a Single protein structure of sequence from Escherichia coli with as ligand. Active as Carbonate dehydratase, with EC number 4.2.1.1 Full crystallographic information is available from OCA.
Reference
Crystal structure of E. coli beta-carbonic anhydrase, an enzyme with an unusual pH-dependent activity., Cronk JD, Endrizzi JA, Cronk MR, O'neill JW, Zhang KY, Protein Sci. 2001 May;10(5):911-22. PMID:11316870
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