3e3f

H. influenzae beta-carbonic anhydrase, variant V47A with 100 mM bicarbonate

spinqualitylabelsall models 3e3f, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3e3f is a 2 chain structure with sequence from Haemophilus influenzae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.3Å Ligands: BCT, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CAN_HAEIN Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The Haemophilus influenzae beta-carbonic anhydrase (HICA) allosteric site variants V47A and G41A were overexpressed and purified to homogeneity. These variants have k(cat)/K(m) values similar to that of the wild-type enzyme and exhibit a similar dramatic decrease in catalytic activity at pH <8.0. However, both HICA-G41A and -V47A were serendipitously found to bind sulfate ion or bicarbonate ion near pairs of Glu50 and Arg64 residues located on the dimerization interface. In the case of HICA-V47A, bicarbonate ions simultaneously bind to both the dimerization interface and the allosteric sites. For HICA-G41A, two of 12 chains in the asymmetric unit bind bicarbonate ion exclusively at the dimerization interface, while the remaining 10 chains bind bicarbonate ion exclusively at the allosteric site. We propose that the new anion binding site along the dimerization interface of HICA is an "escort" site that represents an intermediate along the ingress and egress route of bicarbonate ion to and from the allosteric binding site, respectively. The structural evidence for sulfate binding at the escort site suggests that the mechanism of sulfate activation of HICA is the result of sulfate ion competing for bicarbonate at the escort site, preventing passage of bicarbonate from the bulk solution to its allosteric site. Evidence for a bicarbonate "escort" site in Haemophilus influenzae beta-carbonic anhydrase .,Rowlett RS, Hoffmann KM, Failing H, Mysliwiec MM, Samardzic D Biochemistry. 2010 May 4;49(17):3640-7. PMID:20359198 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Carbonic anhydrase 3D structures

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