Inositol phosphates are recognized as having diverse and critical roles in biological systems.In this report, kinetic studies and TLC analysis indicate that
-propeller phytase is a special class ofinositol phosphatase that preferentially recognizes a bidentate (P-Ca
2+-P) formed between Ca
2+ and twoadjacent phosphate groups of its natural substrate phytate (InsP
6). The specific recognition of a bidentatechelation enables the enzyme to sequentially hydrolyze one of the phosphate groups in a bidentate ofCa
2+-InsP
6 to yield a
myo-inositol trisphosphate (InsP
3) and three phosphates as the final products. Acomparative analysis of
1H- and
13C NMR spectroscopy with the aid of 2D NMR confirms that the chemicalstructure of the final product is
myo-Ins(2,4,6)P
3. The catalytic properties of the enzyme suggest a potentialmodel for how the enzyme specifically recognizes its substrate Ca
2+-InsP
6 and produces
myo-Ins(2,4,6)P
3 from Ca
2+-InsP
6. These findings potentially provide evidence for a selective Ca
2+-InsPs chelationbetween Ca
2+ and two adjacent phosphate groups of inositol phosphates.