title: Effect in vitro of propoxur on kinetics of K+ stimulated PNPPase and protection by thiol reagents.
abstract: Kinetics analysis of K+ stimulated PNPPase was studied in the rat brain synaptosomes in the presence of propoxur. Non-competitive inhibition with respect to activation by PNPP was seen by the decreased maximal velocity (Vmax) without change in Michaelis-Menten Constant (Km). Activation energy values (delta E) were increased suggesting the decreased catalytic potential of the enzyme. It is also observed that dithiothrietol (DTT) (76 microM), cysteine (82 microM) and glutathione (120 microM) neutralized the inhibition of K(+)-PNPPase by propoxur to different extents.
authors.affiliation: Department of Zoology, S.V. University Tirupati, India.
authors.forename: G R
authors.initials: GR
authors.lastname: Babu
authors.forename: G R
authors.initials: GR
authors.lastname: Reddy
authors.forename: W
authors.initials: W
authors.lastname: Rajendra
authors.forename: C S
authors.initials: CS
authors.lastname: Chetty
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000187:drug effects*; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001921:Brain / Q000201:enzymology; D004789:Enzyme Activation; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D011188:Potassium / Q000502:physiology*; D001074:Propoxur / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013439:Sulfhydryl Reagents / Q000494:pharmacology*; D013574:Synaptosomes / Q000201:enzymology; D013696:Temperature
chemical_list: D013439:Sulfhydryl Reagents; D001074:Propoxur; D009597:4-Nitrophenylphosphatase; D011188:Potassium