title: Formation of an oxo-radical of peroxovanadate during reduction of diperoxovanadate with vanadyl sulfate or ferrous sulfate.
abstract: Formation of oxygen radicals during reduction of H(2)O(2) or diperoxovanadate with vanadyl sulfate or ferrous sulfate was indicated by the 1:2:2:1 electron spin resonance (ESR) signals of the DMPO adduct typical of standard ()OH radical. Signals derived from diperoxovanadate remained unchanged in the presence of ethanol in contrast to those from H(2)O(2). This gave the clue that they represent a different radical, possibly (*)OV(O(2))(2+), formed on breaking a peroxo-bridge of diperoxovanadate complex. The above reaction mixtures evolved dioxygen or, when NADH was present, oxidized it rapidly which was accompanied by consumption of dioxygen. Operation of a cycle of peroxovanadates including this new radical is suggested to explain these redox activities both with vanadyl and ferrous sulfates. It can be triggered by ferrous ions released from cellular stores in the presence of catalytic amounts of peroxovanadates.
authors.affiliation: Solid State and Structural Chemistry Unit, Bangalore 560 012, India. ramasarma@hotmail.com
authors.forename: T
authors.initials: T
authors.lastname: Ramasarma
authors.forename: H N
authors.initials: HN
authors.lastname: Ravishankar
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D005296:Ferrous Compounds / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D009243:NAD / Q000378:metabolism; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010545:Peroxides / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry*; D014638:Vanadates / Q000737:chemistry*; D017968:Vanadium Compounds / Q000737:chemistry*
chemical_list: D005296:Ferrous Compounds; D016877:Oxidants; D010545:Peroxides; D017382:Reactive Oxygen Species; D017968:Vanadium Compounds; C091767:diperoxovanadate; C069276:peroxovanadate; D009243:NAD; C020748:ferrous sulfate; D014638:Vanadates; C034028:vanadyl sulfate; D006861:Hydrogen Peroxide; D010100:Oxygen