Lectin inhibition and kinetics of microsomal K+-dependent p-nitrophenyl phosphatase of frog epidermis.
The specific activity of K+-dependent p-NPPase (paranitrophenylphosphatase) from frog (Rana ridibunda) epidermis microsomal preparation was determined. The activity was proportional to time of incubation and protein concentrations under our assays conditions. Optimal phosphatase activity was at pH from 8 to 9 and over 35 degrees C. 10(-3) M ouabain inhibited 100% of the activity and the Ki was estimated about 5 X 10(-5) M. The Km for p-NPP was 3.8 mM and 2.1 for K+. The lectins GSI and GSII produced 80-90% of non-competitive inhibition of the activity. 50% of inhibition by GSI was obtained at 2 micrograms/ml. The Km for p-NPP did not change but the Vmax of activity was clearly reduced for both GSI and GSII lectins.
D009597:4-Nitrophenylphosphatase / Q000037:antagonists & inhibitors*; D000818:Animals; D007700:Kinetics; D037102:Lectins / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology*; D010042:Ouabain / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors*; D011188:Potassium / Q000494:pharmacology*; D011895:Rana ridibunda; D012867:Skin / Q000201:enzymology*
D037102:Lectins; D010042:Ouabain; D010744:Phosphoric Monoester Hydrolases; D009597:4-Nitrophenylphosphatase; D011188:Potassium