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United States Department of Agriculture

Agricultural Research Service

Title: Antioxidant Functions of Inositol 1,2,3-Trisphosphate and Inositol 1,2,3,6-Tetrakisphosphate

Authors
item Phillippy, Brian
item Graf, Ernst - TASTEMAKER

Submitted to: Journal of Biological Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 24, 1998
Publication Date: N/A

Interpretive Summary: Phytic acid, an abundant chemical found in seeds, was converted using enzymes into new compounds that act as antioxidants. These antioxidants form complexes with minerals such as iron that are more soluble than similar complexes containing phytic acid and minerals. The new compounds, called inositol phosphates, are value-added products that may be useful in nutrition, medicine and food preservation.

Technical Abstract: Iron chelates of inositol 1,2,3-trisphosphate and inositol 1,2,3,6-tetrakis In contrast, iron chelates of inositol 1,2,6-trisphosphate and inositol 1,2,5,6-tetrakisphosphate did contain available coordination sites and permitted iron=catalyzed ascorbic acid oxidation and arachidonic acid peroxidation. It was concluded that the 1,2,3-trisphosphate grouping of inositol hexakisphosphate was responsible for the inhibition of iron-catal the phosphates in an axial-equatorial-axial configuration appeared to be the only possible inositol trisphosphate that could form bounds between six oxygen atoms and the six coordination sites on iron. Wheat phosphatases converted inositol hexakisphosphate into at least four products that contain the 1,2,3-trisphosphate grouping. Km values for cleavage by E. Coli alkaline phosphatase were as follows: inositol 1,2,3-trisphosphate, 56 uM; inositol 1,2,6-trisphosphate, 35 uM; inositol 1,2,3,6-tetrakisphosphate, 139 uM; and inositol 1,2,5,6-tetrakisp these four isomers by E. Coli alkaline phosphate were not affected by a three-fold molar excess of iron. Therefore, the antioxidant potential of inositol 1,2,3-trisphosphate and inositol 1,2,3,6-tetrakisphosphate in cells and other biological systems may be modulated by their susceptibility to nonspecific acid and alkaline phosphatases.

Last Modified: 12/22/2014
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