1alk

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spinqualitylabelsall models 1alk, resolution 2.0Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

REACTION MECHANISM OF ALKALINE PHOSPHATASE BASED ON CRYSTAL STRUCTURES. TWO METAL ION CATALYSIS

Overview

Alkaline phosphatase (AP) is a widely distributed non-specific, phosphomonoesterase that functions through formation of a covalent, phosphoseryl intermediate (E-P). The enzyme also catalyzes phosphoryl, transfer reaction to various alcohols. Escherichia coli AP is a homodimer, with 449 residues per monomer. It is a metalloenzyme with two Zn2+ and one, Mg2+ at each active site. The crystal structure of native E. coli AP, complexed with inorganic phosphate (Pi), which is a strong competitive, inhibitor as well as a substrate for the reverse reaction, has been, refined at 2.0 A resolution. Some parts of the molecular have been, retraced, starting from the previous 2.8 A study. The active site has been, modified substantially and is described in this paper. The changes in the, active site region suggest the need to reinterpret earlier spectral data, and suggestions are made. Also presented are the structures of the, Cd-substituted enzyme complexed with inorganic phosphate at 2.5 A, resolution, and the phosphate-free native enzyme at 2.8 A resolution. At, pH 7.5, where the X-ray data were collected, the Cd-substituted enzyme is, predominantly the covalent phosphoenzyme (E-P) while the native Zn/Mg, enzyme exists in predominantly noncovalent (E.P) form. Implication of, these results for the catalytic mechanism of the enzyme is discussed. APs, from other sources are believed to function in a similar manner.

About this Structure

1ALK is a Single protein structure of sequence from Escherichia coli with ZN, MG and PO4 as ligands. Active as Alkaline phosphatase, with EC number 3.1.3.1 Full crystallographic information is available from OCA.

Reference

Reaction mechanism of alkaline phosphatase based on crystal structures. Two-metal ion catalysis., Kim EE, Wyckoff HW, J Mol Biol. 1991 Mar 20;218(2):449-64. PMID:2010919

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