Insect glutathione S-transferases （GSTs） play important roles in detoxifying toxic compounds and eliminating oxidative stress caused by these compounds. In this study, detoxification activity of the epsilon GST S1GS...Insect glutathione S-transferases （GSTs） play important roles in detoxifying toxic compounds and eliminating oxidative stress caused by these compounds. In this study, detoxification activity of the epsilon GST S1GSTE1 in Spodoptera litura was analyzed for several insecticides and heavy metals. S1GSTE1 was significantly up-regulated by chlor- pyrifos and xanthotoxin in the midgut of S. litura. The recombinant S1GSTE1 had Vmax （reaction rate of the enzyme saturated with the substrate） and Km （michaelis constant and equals to the substrate concentration at half of the maximum reaction rate of the enzyme） values of 27.95 ± 0.88μmol/min/mg and 0.87 ± 0.028 mmol/L for glutathione, respec- tively, and Vmax and Km values of 22.96 ± 0,78μmol/min/mg and 0.83 ± 0.106 mmol/L for 1-chloro-2,4-dinitrobenzene, respectively. In vitro enzyme indirect activity assay showed that the recombinant S1GSTE 1 possessed high binding activities to the insecticides chlor- pyrifos, deltamethrin, malathion, phoxim and dichloro-diphenyl-trichloroethane （DDT）. S1GSTE1 showed higher binding activity to toxic heavy metals cadmium, chromium and lead than copper and zinc that are required for insect normal growth. Western blot analysis showed that S1GSTE1 was induced in the gut of larvae fed with chlorpyrifos or cadmium. S1GSTE1 also showed high peroxidase activity. All the results together indicate that S1G- STE1 may play an important role in the gut orS. litura to protect the insect from the toxic effects of these compounds and heavy metals.展开更多
基金This research was supported by National Natural Science Foundation of China （Gram No. 31071981） and National Natural Science Foundation of China （Grant No. 31272381）.
文摘Insect glutathione S-transferases （GSTs） play important roles in detoxifying toxic compounds and eliminating oxidative stress caused by these compounds. In this study, detoxification activity of the epsilon GST S1GSTE1 in Spodoptera litura was analyzed for several insecticides and heavy metals. S1GSTE1 was significantly up-regulated by chlor- pyrifos and xanthotoxin in the midgut of S. litura. The recombinant S1GSTE1 had Vmax （reaction rate of the enzyme saturated with the substrate） and Km （michaelis constant and equals to the substrate concentration at half of the maximum reaction rate of the enzyme） values of 27.95 ± 0.88μmol/min/mg and 0.87 ± 0.028 mmol/L for glutathione, respec- tively, and Vmax and Km values of 22.96 ± 0,78μmol/min/mg and 0.83 ± 0.106 mmol/L for 1-chloro-2,4-dinitrobenzene, respectively. In vitro enzyme indirect activity assay showed that the recombinant S1GSTE 1 possessed high binding activities to the insecticides chlor- pyrifos, deltamethrin, malathion, phoxim and dichloro-diphenyl-trichloroethane （DDT）. S1GSTE1 showed higher binding activity to toxic heavy metals cadmium, chromium and lead than copper and zinc that are required for insect normal growth. Western blot analysis showed that S1GSTE1 was induced in the gut of larvae fed with chlorpyrifos or cadmium. S1GSTE1 also showed high peroxidase activity. All the results together indicate that S1G- STE1 may play an important role in the gut orS. litura to protect the insect from the toxic effects of these compounds and heavy metals.
