Purification of Pumpkin Glutathione S-Transferase Species Specifically Present in Cultured Cells Treated by Excessive Concentration of 2,4-Dichlorophenoxyacetic Acid but Absent in Normal Plants

Abstract

  Pugc is a unique glutathione S-transferase subunit species that is absent in normal pumpkin plants, but GST3c (homodimer of Pugc) accumulates in cultured pumpkin cells treated with 40 ppm 2,4-dichlorophenoxyacetic acid for six days. GST3c was purified by DEAE-cellulose, hydroxylapatite, and S-hexylglutathione-agarose column chromatography, and its homogeneity was confirmed by SDS-PAGE analysis. The specific activity of GST3c was 124 μmol/min/mg protein with 1-chloro-2,4-dinitrobenzene. This was higher than those of the other plant and animal glutathione S-transferases. Mouse antiserum raised against the purified GST3c recognized only Pugc, but not Puga, Pugb, nor Pugd when the reactivity of pumpkin glutathione S-transferase subunits was tested.