Description
Determination of glutathione stransferase activity in crude homogenate of maize weevil (Sitophilus Zeamais) under basal metabolic condition.
Abstract
Glutathione S-transferases (GSTs) are bisubstrate enzymes belonging to the phase II metabolism that catalyze the formation of thioether conjugates between the endogenous tripeptide glutathione and xenobiotic compounds. Glutathione S-transferases Total activity of the maize weevil (Sitophilus Zeamais) GSTswere Determined for Two substrates, 1-chloro-2,4-dinitrobenzene (CDNB) and Ethacrynic acid. The result of total activity showed that CDNB has (0.269µmol/mL.min)while EA (3.8µmol/mL.min). The kinetic parameters were determined and the Michaelis constant (Km) was calculated for both CDNB and GSH. The Km values using CDNB (6.547266µM) were higher as compared to that of GSH (0.603398µM). The data indicate the presence of the enzymes in the maize weevil but the enzyme has lower affinity to the CDNB when compared with GSH. This showed that these enzymes might play a role in the detoxification of insecticides and may possibly contribute to the development of insecticide resistance. The insect was able to detoxify the xenobiotics (CDNB) at a faster rate than their endogenous substrate (GSH)..
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