SEPARATION OF MULTIPLE FORMS OF ACIDIC GLUTATHIONE-S-TRANSFERASE ISOZYMES IN A SUSCEPTIBLE AND A RESISTANT STRAIN OF HOUSE-FLY, MUSCA-DOMESTICA (L)

The acidic glutathione S-transferases from a CSMA (susceptible) strain and a Cornell-R (resistant) strain of houseflies were purified and se parated utilizing affinity chromatography followed by chromatofocusing . Nine fractions were isolated from each house fly strain. Fraction 1 had the highest 1-chloro-2,4-dinitrobenzene vs. 1,2-dichloro-4-nitrobe nzene ratio (CDNB/DCNB ratio) in both strains and the ratio of all the other fractions tended to decrease as the isoelectrical points decrea sed except for fractions 4 and 9. Most fractions from the CSMA strain had higher CDNB conjugation activities than the fractions from the Cor nell-R strain, but all the fractions from the CSMA strain had lower DC NB conjugation activities than fractions from the Cornell-R strain. St eady-state kinetics of all the fractions were examined. The Km values obtained from both strains ranged from 0.36 to 1.12 mM, while the Vmax value ranged from 3.0 to 32.6 mu mol/min/mg. In the 100,000 g superna tant, the CDNB specific activities in the CSMA strain was about 1/3 of the activity in the Cornell-R strain but it was about 1.5-fold follow ing affinity chromatography. The specific activity for DCNB measured i n the CSMA strain was only 1/5 of the activities of the Cornell-R stra in in the 100,000 g supernatant, but was about the same after affinity chromatography. The difference was due to the selectivity of the affi nity column used in the current study. (C) 1995 Wiley-Liss, Inc.