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Publication Abstract from PubMed

Phytases hydrolyze phytic acid to less phosphorylated myo-inositol derivatives and inorganic phosphate. A thermostable phytase is of great value in applications for improving phosphate and metal ion availability in animal feed, and thereby reducing phosphate pollution to the environment. Here, we report a new folding architecture of a six-bladed propeller for phosphatase activity revealed by the 2.1 A crystal structures of a novel, thermostable phytase determined in both the partially and fully Ca2+-loaded states. Binding of two calcium ions to high-affinity calcium binding sites results in a dramatic increase in thermostability (by as much as approximately 30 degrees C in melting temperature) by joining loop segments remote in the amino acid sequence. Binding of three additional calcium ions to low-affinity calcium binding sites at the top of the molecule turns on the catalytic activity of the enzyme by converting the highly negatively charged cleft into a favorable environment for the binding of phytate.

Crystal structures of a novel, thermostable phytase in partially and fully calcium-loaded states.,Ha NC, Oh BC, Shin S, Kim HJ, Oh TK, Kim YO, Choi KY, Oh BH Nat Struct Biol. 2000 Feb;7(2):147-53. PMID:10655618^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.