The action of peroxidase systems on ferrocyanide, molybdate, tungstate and vanadate

Abstract

Kenten & Mann (1950) showed that plant peroxidase preparations in the presence of certain phenolic substrates catalyse the oxidation of Mn++ by hydrogen peroxide. Evidence was obtained that the Mn++ reduces an intermediate oxidation product of the phenolic substrate and thereby is itself oxidized. The oxidizing capabilities of the system peroxidase + phenolic substrate + hydrogen peroxide towards inorganic compounds have now been further investigated. It is shown that the system oxidizes ferrocyanide, and evidence suggesting the oxidation of molybdate, tungstate and vanadate is reported. MATERIALS AND METHODS Peroxida8e preparation8 were obtained from horseradish by the method of Keilin & Mann (1937). The 'Purpurogallinzahl' (P.Z.) of these preparations was determined by the method of Keilin & Mann (1937). Hydroge.n peroxide. In the experiments with molybdate, tungstate and vanadate, approximately 0-05M-H,0, was used, and for the manometric experiments with ferrocyanide approximately 0-025M-H202 in 0-0105m-NaHCO.,. Fresh solutions were prepared for each experiment. The 0-025M-HSOS in NaHCO, was estimated by KMnO, titration and the 0-05m-H202 manometrically with MnO2 in acid solution (Kenten & Mann, 1950). Ammonium permolybdate was prepared by treatment of 100 vol. H202 with molybdate according to the method of

Oxidation of Proteins by Tyrosinase and Peroxidase

“…l'hc arceptor or hydrogen donor molecule iii the pcroxidusc system may hc oxidized to an elid product which readily reacts with an oxidizable molecule such as an amino arid or potassium fcrroryanide a i d (wises its oxidation (81,94,95). Peroxidase lilw tyrosinase oxitlizcs phei t 01 i ( * rom pounds to qiiiii ones which in turn oxidize other compouiicls.…”