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Free Radical produced in the Reaction of Metmyoglobin with Hydrogen Peroxide


IN a previous communication1, it was reported that a free radical is formed during the action of hydrogen peroxide on methæmoglobin. As its g-value approximated to that of a free electron, this result was interpreted in terms of electron removal from the π-orbitals of the porphyrin ring, by analogy with the reactions occurring during the oxidation of porphyrins and phthalocyanines2. This explanation, involving the postulate of little interaction between unpaired electron and central iron atom, conflicted with the results of titration studies3, and the evidence from paramagnetic susceptibility4.

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    Gibson, J. F., and Ingram, D. J. E., Nature, 178, 871 (1956).

  2. 2

    George, P., Ingram, D. J. E., and Bennett, J., J. Amer. Chem. Soc., 79, 1870 (1957).

  3. 3

    George, P., and Irvine, D., Biochem. J., 60, 596 (1955).

  4. 4

    Theorell, H., and Ehrenberg, A., Arch. Biochem. Biophys., 41, 442 (1952).

  5. 5

    George, P., and Irvine, D., Biochem. J., 52, 511 (1952).

  6. 6

    Chance, B., and Fergusson, R. R., “The Mechanism of Enzyme Action” (The Johns Hopkins Press, Baltimore, 1954).

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