title: Roles for glutathione transferases in antioxidant recycling.
abstract: Uniquely among the plant glutathione transferases, two classes possess a catalytic cysteine capable of performing glutathione-dependent reductions. These are the dehydroascorbate reductases (DHARs) and the lambda-class glutathione transferases (GSTLs). Using immobilized GSTLs probed with crude plant extracts we have identified flavonols as high affinity ligands and subsequently demonstrated a novel glutathione-dependent role for these enzymes in recycling oxidized quercetin. By comparing the activities of DHARs and GSTLs we now propose a unified catalytic mechanism that suggests oxidized anthocyanidins and tocopherols may be alternative polyphenolic substrates of GSTLs.
authors.affiliation: Biophysical Sciences Institute, Durham University, Durham, UK.
authors.forename: David P
authors.initials: DP
authors.lastname: Dixon
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Steel
authors.forename: Robert
authors.initials: R
authors.lastname: Edwards
mesh_terms: D000872:Anthocyanins / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011794:Quercetin / Q000378:metabolism*; D024505:Tocopherols / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D000975:Antioxidants; D010940:Plant Proteins; D011794:Quercetin; D010088:Oxidoreductases; C020666:glutathione dehydrogenase (ascorbate); D005982:Glutathione Transferase; D003545:Cysteine; D024505:Tocopherols