2iuc
From Proteopedia
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STRUCTURE OF ALKALINE PHOSPHATASE FROM THE ANTARCTIC BACTERIUM TAB5
Overview
Alkaline phosphatases (APs) are non-specific phosphohydrolases that are, widely used in molecular biology and diagnostics. We describe the, structure of the cold active alkaline phosphatase from the Antarctic, bacterium TAB5 (TAP). The fold and the active site geometry are conserved, with the other AP structures, where the monomer has a large central, beta-sheet enclosed by alpha-helices. The dimer interface of TAP is, relatively small, and only a single loop from each monomer replaces the, typical crown domain. The structure also has typical cold-adapted, features; lack of disulfide bridges, low number of salt-bridges, and a, loose dimer interface that completely lacks charged interactions. The, dimer interface is more hydrophobic than that of the Escherichia coli AP, and the interactions have tendency to pair with backbone atoms, which we, propose to result from the cold adaptation of TAP. The structure contains, two additional magnesium ions outside of the active site, which we believe, to be involved in substrate binding as well as contributing to the local, stability. The M4 site stabilises an interaction that anchors the, substrate-coordinating R148. The M5 metal-binding site is in a region that, stabilises metal coordination in the active site. In other APs the M5, binding area is supported by extensive salt-bridge stabilisation, as well, as positively charged patches around the active site. We propose that, these charges, and the TAP M5 binding, influence the release of the, product phosphate and thus might influence the rate-determining step of, the enzyme.
About this Structure
2IUC is a Protein complex structure of sequences from Antarctic bacterium tab5 with , , and as ligands. Active as Alkaline phosphatase, with EC number 3.1.3.1 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Crystal structure of alkaline phosphatase from the Antarctic bacterium TAB5., Wang E, Koutsioulis D, Leiros HK, Andersen OA, Bouriotis V, Hough E, Heikinheimo P, J Mol Biol. 2007 Mar 2;366(4):1318-31. Epub 2006 Dec 2. PMID:17198711
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