Heavy Metal-Mediated Crystallization of Escherichia Coli Phytase and Analysis of Bridging Interactions

Escherichia coli phytase is a phosphatase that catalyzes the hydrolysis of phytic acid into inorganic phosphate and myo-inositol. Two crystal forms of this enzyme were obtained in the presence of heavy metals.Crystal forms I and II were obtained with the heavy atoms CdCl2 and HgCl2 and diffracted to 1.5 Å and 2.25 Å resolution, respectively. Hg2+ and Cd2+ both acted as molecular bridge(s), linking and stabilizing E. coli phytase in the unit cell, and played a crucial role in the crystallization of phytase by bridging neighbouring symmetry related molecules.