Stimulation of the ATP, Mg-dependent protein phosphatase by p-nitrophenyl phosphate.
The phosphorylase phosphatase activity of the ATP,Mg-dependent protein phosphatase is stimulated by p-nitrophenyl phosphate (pNPP). All the active forms of this type of enzyme show this property, which seems to be unrelated to any pNPP-hydrolyzing activity. The increase in activity is due to an increase in Vm, the Km being unchanged. The possibility that pNPP acts as a deinhibitor is excluded. pNPP acts as a competitive inhibitor on the phosphorylase phosphatase activity of the different polycation-stimulated protein phosphatases. Stimulation by pNPP can be used as a differential criterion in a specific assay of the active forms of the ATP,Mg-dependent phosphatase.
Goris
J
J
Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit te Leuven, Belgium.
Merlevede
W
W
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D008274:Magnesium / Q000494:pharmacology*; D009596:Nitrophenols / Q000494:pharmacology*; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000032:analysis*
D009596:Nitrophenols; D009943:Organophosphorus Compounds; C008644:nitrophenylphosphate; D000255:Adenosine Triphosphate; D010749:Phosphoprotein Phosphatases; D008274:Magnesium