1kop

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spinqualitylabelsall models 1kop, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

NEISSERIA GONORRHOEAE CARBONIC ANHYDRASE

Overview

The crystal structure of carbonic anhydrase from Neisseria gonorrhoeae has, been solved to a resolution of 1.78 A by molecular replacement using human, carbonic anhydrase II as a template. After refinement the R factor was, 17.8% (Rfree=23.2%). There are two molecules per asymmetric unit (space, group P21), but they have essentially identical structures. The fold of, the N. gonorrhoeae enzyme is very similar to that of human isozyme II; 192, residues, 74 of which are identical in the two enzymes, have equivalent, positions in the three-dimensional structures. This corresponds to 85% of, the entire polypeptide chain of the bacterial enzyme. The only two, cysteine residues in the bacterial enzyme, which has a periplasmic, location in the cell, are connected by a disulfide bond. Most of the, secondary structure elements present in human isozyme II are retained in, N. gonorrhoeae carbonic anhydrase, but there are also differences, particularly in the few helical regions. Long deletions in the bacterial, enzyme relative to human isozyme II have resulted in a considerable, shortening of three surface loops. One of these deletions, corresponding, to residues 128 to 139 in the human enzyme, leads to a widening of the, entrance to the hydrophobic part of the active site cavity. Practically, all the amino acid residues in the active site of human isozyme II are, conserved in the N. gonorrhoeae enzyme and have similar structural, positions. However, the imidazole ring of a histidine residue, which has, been shown to function as a proton shuttle in the catalytic mechanism of, the human enzyme, interacts with an extraneous entity, which has, tentatively been identified as a 2-mercaptoethanol molecule from the, crystallization medium. When this entity is removed by soaking the crystal, in a different medium, the side-chain of His66 becomes quite mobile. The, structure of a complex with the sulfonamide inhibitor, acetazolamide, has, also been determined. Its position in the active site is very similar to, that observed in human carbonic anhydrase II.

About this Structure

1KOP is a Single protein structure of sequence from Neisseria gonorrhoeae with ZN, AZI, SO4 and BME as ligands. Active as Carbonate dehydratase, with EC number 4.2.1.1 Full crystallographic information is available from OCA.

Reference

Crystal structure of carbonic anhydrase from Neisseria gonorrhoeae and its complex with the inhibitor acetazolamide., Huang S, Xue Y, Sauer-Eriksson E, Chirica L, Lindskog S, Jonsson BH, J Mol Biol. 1998;283(1):301-10. PMID:9761692

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