The characterization by affinity chromatography of glutathione S-transferases from different strains of house fly

Glutathione S-transferases have been partially purified from five strains of house fly of defined resistance to insecticides. Apparent purification factors of 1.8–25 were obtained, the degree of purification depending on the assay substrate employed. Yields of up to 100% were obtained when 3,4-dichloronitrobenzene was used as substrate but with 1-chloro-2,4-dinitrobenzene as substrate the yields were of the order of 20–30%. Qualitative analysis of the proteins in these preparations indicated a high degree of similarity between the Cornell and Hirokawa strains and also a resemblance between the Fc and Rutgers strain. In the Cornell and Hirokawa strains, the bulk of the enzyme activity is attributed to two proteins (constituting a major fraction of the protein in the extracts) which appear to be of different isoelectric point from the proteins associated with enzyme activity in the Rutgers, Fc, and CSMA strains. A minor component in the Hirokawa and Cornell preparations appeared to correspond to the major catalytic protein in the Rutgers extract. On the basis of the above data, it is proposed that the various strains may possess a multiplicity of GSH S-transferases, common to all, individual proteins being present to varying extents in the different strains.