title: Assay of inorganic phosphate in the mild pH range, suitable for measurement of glycogen phosphorylase activity.
abstract: A spectrophotometric assay of orthophosphate at mild pH is described. Phosphomolybdate complex is reduced by ascorbic acid at pH 5.0 in the presence of Zn2+. The chromophore produced is measured at 850 nm. The method is simple and sensitive, and the reaction proceeds normally in the presence of "interfering substances" such as metal-chelating agents and thiol compounds. The method could be widely employed for the assay of phosphate-releasing reaction from labile organic phosphates, such as for the assay of glycogen phosphorylase.
mesh_terms: D000085:Acetates; D019342:Acetic Acid; D001205:Ascorbic Acid; D006863:Hydrogen-Ion Concentration; D008982:Molybdenum; D010084:Oxidation-Reduction; D010710:Phosphates / Q000032:analysis*; D006005:Phosphorylases / Q000032:analysis*; D013053:Spectrophotometry / Q000379:methods
chemical_list: D000085:Acetates; D010710:Phosphates; D008982:Molybdenum; D006005:Phosphorylases; C022175:ammonium molybdate; D001205:Ascorbic Acid; D019342:Acetic Acid