Purification of GSH-S-transferase from <i>Plutella xylostella </i>larvae and its inhibition by organotin compounds

Abstract

Abstract Glutathione-S-transferases have been detected in the insecticide-resistant and susceptible strains of the larvae of Piute/la xylostella, a major pest of cruciferous vegetables. Although there was no significant difference in the enzyme-substrate affinities (Km) for glutathione (GSH) and 1-chloro- 2,4-dinitrobenzene (CDNB), the enzyme was present in almost five-fold excess in the resistant strain than in the susceptible strain. The enzyme in the crude supernatant suffered a marked loss in activity on standing; its activity, however, could be stabilized by thiol reagents such as 2-mercaptoethanol, cysteine or GSH, but not with metal ions.