p-Nitrophenylacetate hydrolysis by honey bee esterases: kinetics and inhibition.
1. The kinetics and inhibition of p-nitrophenylacetate hydrolysis by cytosolic esterases of 1-day old female honey bees, Apis mellifera L., were studied. 2. The calculated values obtained were Km = 2.27 x 10(-5)M and Vmax = 2.48 x 10(-8) mol/s per mg protein. 3. The inhibition mechanisms examined for four organophosphorus insecticides were highly competitive in nature and based on competitive inhibition coefficients the order of toxicity was naled > dichlorvos > cis-mevinphos = trans-mevinphos. 4. Comparisons are made with the alfalfa leafcutting bee, Megachile rotundata (Fab).
Department of Biochemistry, University of Arizona, Tucson 85721.
J E
JE
Spoonamore
D R
DR
Frohlich
M A
MA
Wells
D000818:Animals; D001516:Bees / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D004950:Esterases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D005260:Female; D006722:Honey; D006868:Hydrolysis; D008658:Inactivation, Metabolic; D007306:Insecticides / Q000493:pharmacokinetics; D007700:Kinetics; D000455:Medicago sativa; D009596:Nitrophenols / Q000378:metabolism*; D009943:Organophosphorus Compounds
D007306:Insecticides; D009596:Nitrophenols; D009943:Organophosphorus Compounds; C008642:4-nitrophenyl acetate; D004950:Esterases