Glutathione S-Transferases Predominantly Accumulate in Pumpkin Culture Cells Exposed to Excessive Concentrations of 2, 4-Dichlorophenoxyacetic Acid

抄録

Effects of high concentrations of 2, 4-dichlorophenoxyacetic acid on glutathione S-transferases, Puga, Pugb, Pugc, and Pugd, in pumpkin culture cells were investigated. When the culture cells were transferred from a standard medium containing 1ppm 2, 4-dichlorophenoxyacetic acid to the medium containing 40ppm, specific activity of GST in the cells increased four-fold. By two-dimensional electrophoresis, it was ascertained that the increase in specific activity of GST was due to specific elevation of levels of the GST proteins among soluble proteins from the culture cells. Each GST protein, however, had its own rate in its increase. Puga increased most intensively, so that the ratios of GST isozymes containing Puga increased markedly. Hence, Puga could be easily purified to homogeneity on SDS-PAGE from the culture cells treated with 40ppm 2, 4-dichlorophenoxyacetic acid. Differences between peptide patterns of Puga and Pugb digested partially with trypsin, and heterogeneity in cross-reactivities of GSTs with anti-Puga rabbit serum suggested that the primary structure of Puga might be different from those of the other pumpkin GSTs.