Bio-activity of Phytate-Metal Complexes and Its Regulation of Hydrolysis Enzyme Phytase

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We made the structure-property relations for metal-phytate complexes clear and showed that the specific properties of metal-phytate complexes is usefully available in biological system.(1) Interactions of phytate with metal ionsStability constants of various metal-phytate species were evaluated by pH titrations and were able to give the structural information as well as the spectra. These showed the importance of hydrogen bond between the phosphate group which also determines the metal coordination site.(2) Metal ions dependence of enzyme phytase activityEnzyme phytase from Aspergillus niger is considered to be a model of active bio-molecular receptor of phytate. This enzyme reaction rate were varied by various metal ions which assist the formation of reactive substrate of phytate at pH 6, Metal-phytate-H5. Here we demonstrated new aspect of the metal ion that the substrate of phytase is a metal complex.(3) Bio-activity of Metal-phytate complexLi^+ inhibition of phytase reaction and strong interaction of Li-phytate complex indicated possible relationship with the antidepressant activityof Li^+. Anti-cancer effect of various metal-phytate complexes were studied by growth inhibition of human KB cell. All metal system, especially Ca^<2+>, were more effective than phytate 12Na and this indicated Ca-phytate complex as a true active species.These results obtained here were served a base for application of phytate and phytase to medical drugs.