1i6p
From Proteopedia
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. 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 Page seeded by OCA on Fri May 2 19:38:19 2008
