title: The mode of reduction of vanadate(+V) to oxovanadium(+IV) by glutathione and cysteine.
abstract: Vanadate(+V) is completely reduced to oxovanadium(+IV) in vitro by thiols. A high transient absorbance at 750 nm is observed (intense blue) in solutions of a pH below 5 immediately after starting the reduction. EPR-measurements and determinations of the consumption of free thiol groups prove that the transient absorbance is caused by an intermediate compound not containing vanadium in its reduced state (+IV). The way of reduction of vanadate(+V) by thiols is discussed. We propose the formation of an intermediate vanadate(+V)-thioester which is formed before reduction in a preequilibrium step.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D003545:Cysteine; D004578:Electron Spin Resonance Spectroscopy; D005978:Glutathione; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D010087:Oxides; D013053:Spectrophotometry; D013438:Sulfhydryl Compounds; D014638:Vanadates; D014639:Vanadium
chemical_list: D010087:Oxides; D013438:Sulfhydryl Compounds; D014639:Vanadium; D014638:Vanadates; D005978:Glutathione; D003545:Cysteine