Iron-Ethylenediaminetetraacetic acid (ED JAI-Catalyzed Superoxide Dismutation Revisited: An Explanation of Why the Dismutase Activity of Fe-EDJA Cannot Be Detected in the Cytochrome c/Xanthine Oxidase Assay System’
نویسنده
چکیده
The recent assertion of J. Diguiseppi and I. Fridovich (1980, Arch. Biochem. Biophgs. 203,145-150) that Fe-EDTA does not catalyze superoxide dismutation is disputed. By directly observing superoxide generated during pulse radiolysis, we have confirmed the results of a previous study (G. J. McClune, J. A. Fee, G. A. McClusky, and J. T. Groves, 1977, J. Amer. Chem. Sot 99, 5220-5222) which concluded that Fe-EDTA catalyzed superoxide dismutation. We also demonstrate that the reaction of Fe(II)-EDTA, formed during catalyzed superoxide dismutation, with cytochrome c, the probe molecule in the cytochrome c/xanthine oxidase/xanthine assay system for superoxide dismutase activity, is sufficiently rapid (H. L. Hodges, R. A. Holwerda, and H. B. Gray, 1974, J. Amer. Chem. SIX. 96,3132-3137) to obscure the weak catalysis of superoxide dismutation by Fe-EDTA.
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