Effect of acaricides on the activity of a Boophilus microplus glutathione S-transferase

In the present study, we report the effect of several acaricides on the enzyme activity of a Boophilus microplus recombinant glutathione S-transferase (rGST). GST was expressed in Escherichia coli and was purified with glutathione (GSH) affinity column chromatography. The kinetic constants were determined by reacting GST with the substrates 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione. We report the effect of several acaricides on the enzyme activity of rGST. Some acaricides (ethion, amitraz, chlorpyrifos, DDT, cypermethrin, diazinon, ivermectin, deltamethrin and flumethrin) inhibited rGST. Contrarily, coumaphos had an activating effect. Although the accurate mechanisms of the B. microplus resistance to acaricides remain elusive, this work helps in understanding how acaricides can interact with GST. (C) 2003 Elsevier B.V. All rights reserved.