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Ye, B., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Faltin, Z., Dept. Fruit-Tree Breed. and Genet., Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Ben-Hayyim, G., Dept. Fruit-Tree Breed. and Genet., Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Eshdat, Y., Dept. Fruit-Tree Breed. and Genet., Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Gressel, J., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Glutathione peroxidase is involved in scavenging free radicals in many biological systems. Its presence in plants has been implicated by identification of genes with nucleotide sequences similar to those of mammals, as well as by indirect, coupled enzyme assays. We directly quantified glutathione peroxidase activity in crude plant extracts using an organic hydroperoxide substrate and measuring GSSG, the direct reaction product, by adapting a sensitive fluorometric method. The constitutive levels of glutathione peroxidase in a paraquat-resistant biotype of Conyza bonariensis (resistant to many oxidative stresses) were almost double those of the sensitive biotype, providing correlative evidence that glutathione peroxidase is part of the system preventing oxidative damage. Glutathione peroxidase activity was separated from both glutathione transferase and glutathione reductase activities by specific antibody immunoprecipitation and by substrate-affinity chromatography. Conyza glutathione peroxidase cross-reacted with citrus polyclonal anti-phospholipid hydroperoxide glutathione peroxidase. The data suggest that this glutathione peroxidase is a component of the systems dealing with oxidative damage protection in plants and is biochemically different from glutathione peroxidases that also have glutathione transferase activity. (C) 2000 Academic Press.
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Correlation of glutathione peroxidase to paraquat/oxidative stress resistance in Conyza determined by direct fluorometric assay
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Ye, B., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Faltin, Z., Dept. Fruit-Tree Breed. and Genet., Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Ben-Hayyim, G., Dept. Fruit-Tree Breed. and Genet., Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Eshdat, Y., Dept. Fruit-Tree Breed. and Genet., Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Gressel, J., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Correlation of glutathione peroxidase to paraquat/oxidative stress resistance in Conyza determined by direct fluorometric assay
Glutathione peroxidase is involved in scavenging free radicals in many biological systems. Its presence in plants has been implicated by identification of genes with nucleotide sequences similar to those of mammals, as well as by indirect, coupled enzyme assays. We directly quantified glutathione peroxidase activity in crude plant extracts using an organic hydroperoxide substrate and measuring GSSG, the direct reaction product, by adapting a sensitive fluorometric method. The constitutive levels of glutathione peroxidase in a paraquat-resistant biotype of Conyza bonariensis (resistant to many oxidative stresses) were almost double those of the sensitive biotype, providing correlative evidence that glutathione peroxidase is part of the system preventing oxidative damage. Glutathione peroxidase activity was separated from both glutathione transferase and glutathione reductase activities by specific antibody immunoprecipitation and by substrate-affinity chromatography. Conyza glutathione peroxidase cross-reacted with citrus polyclonal anti-phospholipid hydroperoxide glutathione peroxidase. The data suggest that this glutathione peroxidase is a component of the systems dealing with oxidative damage protection in plants and is biochemically different from glutathione peroxidases that also have glutathione transferase activity. (C) 2000 Academic Press.
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