title: Protein tyrosine phosphatase: enzymatic assays.
abstract: Activity assays for tyrosine phosphatases are based on the hydrolysis of a arylphosphate moiety from a synthetic substrate yielding a spectroscopically active product. Many different substrates can be used for these assays with p-nitrophenyl phosphate (pNPP), fluorescein diphosphate (FDP), and 6,8-difluoro-4-methylumbellyferyl phosphate (DiFMUP) being the most efficient and versatile. Equally, larger molecules such as phosphotyrosyl peptides can also be used to mimic more natural substrates. Activity assays include the determinations of the rate of dephosphorylation and calculations of kinetic constants such as k(cat) and K(M). These assays are useful to identify and characterize tyrosine phosphatases and are commonly used to evaluate the efficiency of inhibitors.
authors.affiliation: Department of Biochemistry and Molecular Biology, Merck Frosst Center for Therapeutic Research, P.O. Box 1005, Pointe-Claire, Que., Canada H9R 4P8.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Montalibet
authors.forename: Kathryn I
authors.initials: KI
authors.lastname: Skorey
authors.forename: Brian P
authors.initials: BP
authors.lastname: Kennedy
mesh_terms: D005452:Fluoresceins; D006863:Hydrogen-Ion Concentration; D006923:Hymecromone / Q000031:analogs & derivatives*; D007700:Kinetics; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000032:analysis* / Q000037:antagonists & inhibitors
chemical_list: C119285:6,8-difluoro-4-methylumbelliferyl phosphate; D005452:Fluoresceins; D009596:Nitrophenols; D009943:Organophosphorus Compounds; C008644:nitrophenylphosphate; D006923:Hymecromone; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases