title: The radiometric assay of alkaline phosphatase activity with 125-I-labelled phenolphthalein monophosphate.
abstract: The coupling of 125-I to phenolphthalein monophosphate is described. Hydrolytic cleavage of the phosphate group by alkaline phosphatases (EC 3.1.-3.1) releases labelled phenolphthalein which is extracted into ethyl acetate at pH 10. This forms the basis of a sensitive assay for the enzyme with the advantages of sensitivity and rapidity from the use of a gamma-emitter. Results with Escherichia coli and calf intestine alkaline phosphatases are presented.
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis* / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007422:Intestines / Q000201:enzymology; D007457:Iodine Radioisotopes; D007700:Kinetics; D008722:Methods; D009943:Organophosphorus Compounds; D010635:Phenolphthaleins; D013045:Species Specificity; D013997:Time Factors
chemical_list: D007457:Iodine Radioisotopes; D009943:Organophosphorus Compounds; D010635:Phenolphthaleins; D000469:Alkaline Phosphatase