title: Model studies of the iron-catalysed Haber-Weiss cycle and the ascorbate-driven Fenton reaction.
abstract: Complementary hydroxylation assays and stopped-flow e.s.r. techniques have been employed in the investigation of the effect of various iron chelators (of chemical, biological and clinical importance) on hydroxyl-radical generation via the Haber-Weiss cycle and the ascorbate-driven Fenton reaction. Chelators have been identified which selectively promote or inhibit various reactions involved in hydroxyl-radical generation (for example, NTA and EDTA promote all the reactions of both the Haber-Weiss cycle and the ascorbate-driven Fenton reaction, whereas DTPA and phytate inhibit the recycling of iron in these reactions). The biological chelators succinate and citrate are shown to be relatively poor catalysts of the Haber-Weiss cycle, whereas they are found to be effective catalysts of .OH generation in the ascorbate-driven Fenton reaction. It is also suggested that continuous redox-cycling reactions between iron, oxygen and ascorbate may represent an important mechanism of cell death in biological systems.
authors.affiliation: Department of Chemistry, University of York, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Burkitt
authors.forename: B C
authors.initials: BC
authors.lastname: Gilbert
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism*; D002951:Citrates / Q000378:metabolism; D019343:Citric Acid; D004492:Edetic Acid / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000378:metabolism; D005296:Ferrous Compounds / Q000378:metabolism; D006878:Hydroxides / Q000378:metabolism; D017665:Hydroxyl Radical; D006900:Hydroxylation; D007501:Iron / Q000378:metabolism*; D009571:Nitrilotriacetic Acid / Q000378:metabolism; D010084:Oxidation-Reduction; D004369:Pentetic Acid / Q000378:metabolism; D010833:Phytic Acid / Q000378:metabolism; D012459:Salicylates / Q000378:metabolism; D020156:Salicylic Acid; D013386:Succinates / Q000378:metabolism; D019802:Succinic Acid; D019820:Xanthine; D014969:Xanthine Oxidase / Q000378:metabolism; D014970:Xanthines / Q000378:metabolism
chemical_list: D002951:Citrates; D005290:Ferric Compounds; D005296:Ferrous Compounds; D006878:Hydroxides; D012459:Salicylates; D013386:Succinates; D014970:Xanthines; D019820:Xanthine; D019343:Citric Acid; D017665:Hydroxyl Radical; D004369:Pentetic Acid; D010833:Phytic Acid; D004492:Edetic Acid; D019802:Succinic Acid; D007501:Iron; D014969:Xanthine Oxidase; D009571:Nitrilotriacetic Acid; D020156:Salicylic Acid; D001205:Ascorbic Acid