Catalase degrades diperoxovanadate and releases oxygen

On incubation with catalase diperoxovanadate was found to be degraded, showing a decrease in its absorbance at 356 nm and a loss of its peak with a chemical shift at -706 ppm in its 51V NMR spectrum. The products of the reaction had an absorption peak at 266 nm and chemical shifts at -569 and -578 ppm in NMR spectra assigned to dimer and tetramer of vanadate, respectively. Catalase released half the molecular equivalent of oxygen during this degradation of diperoxovanadate with a rate two orders of magnitude lower than that seen with H2O2. By substituting for and not releasing H2O2, diperoxovanadate supported scopoletin oxidation by horseradish peroxidase, as indicated by the reaction being not sensitive to catalase, unlike that seen with H2O2. Catalase-dependent oxygen release was sensitive to azide with both H2O2 and diperoxovanadate as substrates, whereas EDTA selectively inhibited this reaction with diperoxovanadate. The results bring out the potential of catalase in degrading diperoxovanadate and suggest caution in the use of this enzyme to destroy excess H2O2 during preparation of this compound.