A comparison of horseradish peroxidase and manganese ions as catalysts for the oxidation of dihydroxyfumaric acid |
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Authors: | E. F. Hartree |
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Affiliation: | Molteno Institute and Agricultural Research Council Unit of Reproductive Physiology and Biochemistry, University of Cambridge |
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Abstract: | With horseradish peroxidase as catalyst the main product was dihydroxytartrate, but small amounts of glycolaldehyde, mesoxalic semialdehyde, mesoxalate and possibly glyoxal were also formed. Mn(2+) catalysis gave rise only to mesoxalate and oxalate. When oxygen uptake was followed by a manometric method the rate of the peroxidase-catalysed reaction was proportional to oxygen concentration and marked inhibition by cyanide was obtained only at low buffer concentration. The catalytic effects of peroxidase and Mn(2+) were almost always additive. Chelating agents inhibited the Mn(2+)-catalysed reaction, but had either no effect or a slight accelerating effect on the peroxidase-catalysed reaction. It is concluded that Mn(2+) does not function as cofactor in the peroxidase-catalysed oxidation. |
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