THE EFFECT OF SELECTED PESTICIDES ON THE ACTIVITY OF GLUTAMATE KINASEENZYME IN WINTER-WHEAT LEAVES

The regulation of glutamate kinase [E.C.2.7.2.111 enzyme was studied i n winter wheat leaves by selected pesticides (Aminex Pur, Arelon 75 WP , Bayleton 25 WP, Baytan Universal 19.5 WS, Impact Super, Starane 2, a nd Tilt 250 EC). Glutamate catalyzes the first reaction of proline bio synthesis from glutamine, acid, that is conversion of glutamine acid i nto gama-glutamyl phosphate. Winter wheat plants were cultivated in th e glasshouse to 14 years of age (3 right leaves). Acetone powders, whi ch were extracted by 0.05 mol l-1 of potassium phosphate buffer at pH = 7.2 for 30 minutes, were prepared from the leaves. Extracts were cen trifuged for 20 minutes, at 22,000 9, 0-degrees-C. Supernatants obtain ed were salted out by crystalline ammonium sulphate and after centrifu gation for 10 minutes, at 6,000 g, 0-degrees-C the sediments were diss olved in minimum-required volume of 0.05 mol.l-1 of potassium phosphat e buffer and then used to determine glutamate kinase activity. Glutama te activity was determined by hydroxamate method after Y o s h i n a g a et al. (1975). Modified incubation mixture of 1 nil volume (V a s a k o v a , 1980) was used for incubation. In regulation of glutamate k inase enzyme activity in winter wheat leaves by selected pesticides it was found out that the preparations Arelon, Bayleton and Impact acted as partial inhibitors at 0.1 % concentration in an incubation mixture . The preparations Aminex, Baytan, Starane and Tilt were manifested as complete inhibitors at the above concentration. The complete inhibiti on remained unchanged with the preparations Aminex arid Tilt (at the c oncentration of preparations 0.01 %), and with the preparations Baylet on, Impact and Starane the inhibitory action was reduced. Arelon in th is concentration acted as the promoter of glutamate kinase (rab. I). M oreover, the effect of pesticides on the glutamate kinase activity has been studied in the presence of L-proline in incubation mixture. None of the pesticides used in the experiment released L-proline from effe ctor's centre of glutamate kinase and eliminated its alosteric inhibit ion (Tab. II).