Ca2+-Inositol Phosphate Chelation Mediates the Substrate Specificity of -Propeller Phytase
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- 作者：Byung-Chul Oh ; Myung Hee Kim ; Bong-Sik Yun ; Won-Chan Choi ; Sung-Chun Park ; Suk-Chul Bae ; Tae-Kwang Oh
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：August 8, 2006
- 年：2006
- 卷：45
- 期：31
- 页码：9531 - 9539
- 全文大小：270K
- 年卷期：v.45,no.31(August 8, 2006)
- ISSN：1520-4995
文摘
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-Ca2+-P) formed between Ca2+ and twoadjacent phosphate groups of its natural substrate phytate (InsP6). The specific recognition of a bidentatechelation enables the enzyme to sequentially hydrolyze one of the phosphate groups in a bidentate ofCa2+-InsP6 to yield a myo-inositol trisphosphate (InsP3) 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)P3. The catalytic properties of the enzyme suggest a potentialmodel for how the enzyme specifically recognizes its substrate Ca2+-InsP6 and produces myo-Ins(2,4,6)P3 from Ca2+-InsP6. These findings potentially provide evidence for a selective Ca2+-InsPs chelationbetween Ca2+ and two adjacent phosphate groups of inositol phosphates.
-propeller phytase is a special class ofinositol phosphatase that preferentially recognizes a bidentate (P-Ca2+-P) formed between Ca2+ and twoadjacent phosphate groups of its natural substrate phytate (InsP6). The specific recognition of a bidentatechelation enables the enzyme to sequentially hydrolyze one of the phosphate groups in a bidentate ofCa2+-InsP6 to yield a myo-inositol trisphosphate (InsP3) 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)P3. The catalytic properties of the enzyme suggest a potentialmodel for how the enzyme specifically recognizes its substrate Ca2+-InsP6 and produces myo-Ins(2,4,6)P3 from Ca2+-InsP6. These findings potentially provide evidence for a selective Ca2+-InsPs chelationbetween Ca2+ and two adjacent phosphate groups of inositol phosphates.