Purification and Identification of Glutathione S-transferase in Rice Root under Cadmium Stress

Cadmium (Cd) contamination in paddy soils poses a serious threat to the production and quality of rice. Among various biochemical processes related to Cd detoxification in rice, glutathione S-transferase (GST) plays an important role, catalyzing Cd complexation with glutathione (GSH) and scavenging reactive oxygen species (ROS) in cells. In this study, a hydroponic experiment was conducted to investigate the response of GST isozymes in rice roots upon Cd exposure. Results showed that the GST activity in rice roots was clearly enhanced by 50 μmol/L Cd treatment for 7 d. The GST isozymes were purified by ammonium sulphate precipitation, gel filtration chromatography and affinity chromatography. After being separated by SDS-PAGE and visualized by silver staining, GSTU6 was identified by in-gel digestion, MALDI-TOF-MS analysis and peptide mass fingerprint. The results confirm the vital function of tau class rice GST in Cd detoxification.