Purification, crystallization and preliminary X-ray analysis of the Escherichia coli phytase.
A recombinant form of Escherichia coli phytase, which hydrolyzes phytic acid into phosphate and myo-inositol, has been expressed, purified and crystallized. Crystals have been obtained by the method of bulk crystallization in 10 mM sodium acetate buffer (pH 4.5) without using a conventional precipitant. The enzyme crystallized in space group P21, with unit-cell dimensions a = 74.9, b = 72.2, c = 82.4 A, and beta = 92.0 degrees. Crystals diffract to at least 2.2 A at a rotating-anode X-ray source and a 2.3 A resolution data set has been collected, giving completeness of 98.0% and an Rsym of 0.072. Assuming there are two phytase molecules in the asymmetric unit, the solvent content is calculated to be 42.1%. A self-rotation function shows a clear twofold non-crystallographic symmetry relating two molecules of E. coli phytase in the asymmetric unit.
Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada. jia@crystal.biochem.queensu.ca
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D010832:6-Phytase / Q000737:chemistry* / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D011487:Protein Conformation
D001426:Bacterial Proteins; D010832:6-Phytase