The scavenging of superoxide radical by manganous complexes: In vitro

摘要: Abstract Dialyzable manganese has been shown to be present in millimolar concentrations within cells of Lactobacillus plantarum and related lactic acid bacteria. This unusual accumulation Mn appears serve the same function as Superoxide dismutase (SOD), conferring hyperbaric oxygen tolerance on these SOD-free organisms. The form bacteria mechanisms whereby it protects cell from damage are unknown. report examines by which catalytically scavenges O2−, both xanthine oxidase/cytochrome c SOD assay a number vitro systems relevant vivo situation. In all reaction mixtures examined, Mn(II) is first oxidized O2− Mn(III), H2O2 formed. pyrophosphate buffer Mn(III) thus formed re-reduced second making true metal-catalyzed dismutation like that catalyzed SOD. Alternatively, if takes place orthophosphate or other buffers, preferentially reduced largely reductants than such thiols, urate, hydroquinone, H2O2. H2O2, common product bacteria, reacted rapidly with O2, apparently without intermediate O2 release. Free hexaquo ions were electron spin resonance spectroscopy activity assays noncomplexing buffers poorly reactive O2−. contrast, complexes having high catalytic scavenging organic acids, including malate, pyruvate, propionate, succinate, lactate, Mn-lactate complex showing greatest activity.