L-ascorbic acid preincubation with rabbit kidney (Na+-K+)-ATPase inhibits the activity of p-nitrophenylphosphatase partial reaction with a pseudo-first order decay. The presence of the pseudosubstrate, p-nitrophenylphosphate, counteracts the inhibiting effect. During the reaction course, the kinetic rate is enhanced at ascorbic acid concentrations below 0.7 mmol/1, but is inhibited above that amount. The intrinsic fluorescence of the enzyme in E1 and E2 conformations is modified suggesting the occurrence of ascorbate-induced intermediate forms, distinct from those provoked by the addition of cations, magnesium and phosphate. These destabilized forms appear easier to be converted into catalytically active or increasingly inhibited states.
|Numero di pagine||9|
|Rivista||Italian Journal of Biochemistry|
|Stato di pubblicazione||Pubblicato - 1988|
- Ascorbic Acid
- Phosphoric Monoester Hydrolases
- Protease Inhibitors
- Sodium-Potassium-Exchanging ATPase