ARS | Publication request: Characterization of Phosphohydrolases Using Organophosphates

Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: September 6, 2006
Publication Date: November 12, 2006
Citation: Tazisong, I.A., Senwo, Z.N., Taylor, R., He, Z. 2006. Characterization of Phosphohydrolases Using Organophosphates. Soil Science Society of America Annual Meeting. cd-rom

Technical Abstract: The ease of organophosphate mineralization resulting in release of inorganic phosphorus (Pi) for plant uptake largely depends on the stereochemical structure of the compound, the types and sources of enzymes involved, and certain environmental factors. We determined the kinetic parameters (Vmax, Km, Kcat, and Kcat/Km) of phosphomonoesterase and phytase from various sources on seven substrates [p-Nitrophenyl phosphate, Bis-P-Nitrophenyl phosphate, P-Nitrophenyl phosphate bis(cyclohexylammonium), P-Nitrophenyl phosphate di(2-amino-2-ethyl-1-3-propanediol), D-Glucose 6-phosphate sodium salt, D-Glucose 6-phosphate disodium salt, and inositol hexakisphosphate] to assess hydrolytic response under standard conditions. Results from this study revealed that the Vmax, Km (the binding affinity), Kcat (turnover number) and Kcat/Km (catalytic efficiency) values were different for similar enzymes from different sources. A similar trend was observed for Ea and Q10. This study suggests that the optimal condition for enzyme activity is highly dependent on the substrate. This study enhances our understanding of the biogeochemical cycling of organophosphates in the environment.