Submitted to: Journal of Food Agriculture and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2008
Publication Date: 10/5/2008
Citation: Tazisong, I.A., Senwo, Z.N., Taylor, R.W., He, Z. 2008. Hydrolysis of organic phosphates by commercially available phytases: Biocatalytic potentials and ion on their enzymatic activities. Journal of Food Agriculture and Environment. 6:500-505. Interpretive Summary: Phytase is a group of enzymes which release inorganic phosphorus (P) from the organic phosphorus compound phytate. Commercially available phytases from both wheat and the fungus Aspergillus ficuum have been used in environmental and agricultural phosphorus research. Experiments were conducted to better understand the properties of these two phytases. We found that the phytases from wheat and fungus differed in their ability to convert organic P into forms available to plants. Information obtained in this research is helpful for assessing the potential application of the two phytases for controlling phosphorus pollution.
Technical Abstract: Commercially available phytases from wheat and the fungus Aspergillus ficuum have been used in environmental and agricultural phosphorus research. In order to better understand the biochemical properties of these two phytases, in vitro experiments were conducted to study their catalytic potentials to hydrolyze a number of representative organic phosphates [phytate; p-nitrophenyl phosphate (PNP); p-nitrophenyl phosphate di-2-amino-2-ethyl-1-3-propanediol (PNP2A2E); p-nitrophenyl phosphate bis-cyclohexylammonium (PNPBC); bis-p-nitrophenyl phosphate (Bis-PNP); D-glucose 6-phosphate sodium salt (DG6PNa); and D-glucose 6-phosphate disodium salt (DG6P2Na)]. The results showed that the activity of wheat phytase in hydrolyzing these substrates was in the order: phytate > PNPBC > PNP2A2E > PNP > DG6P2Na > DG6PNa > Bis-PNP. Substrate preference for the fungal phytase followed the pattern: phytate > PNP > PNP2A2E > PNPBC. The kinetic constants of the two enzymes on these substrates demonstrated that binding affinity for fungal phytase with phytate was the highest. We further observed that As, Ba, Br, and I ions enhanced fungal phytase activity, whereas wheat phytase activity was suppressed by most ions tested. Information obtained in this research is helpful for assessing the potential application of both phytases for ameliorating phosphate pollution.