Associated with diabetic complications, myo-inositol oxygenase is a binuclear non-Heme iron enzyme that catalyzes the oxidation of myo-inositol to D-glucruonate, a 4-electron process. The active form of the enzyme harbors a Fe(II)Fe(III) cluster rather than a biferrous cluster and forms a superoxo, rather than a peroxo, intermediate. We have spectroscopically defined the biferrous and Fe(II)Fe(III) forms and their substrate interactions using a near-IR circular dichroism (CD), magnetic circular dichroism (MCD), and variable temperature variable field (VTVH) MCD methodology developed in our lab. Our results show a coordinately saturated biferrous site that becomes unsaturated upon one electron oxidation and MI binding, activating the enzyme to bind O2 as superoxide. One electron reductive activation of O2 is now becoming an important reaction coordinate in Bioinorganic Chemistry.

VTVH MCD studies of substrate activation of the binuclear nonheme iron active site of myo-inositol oxygenase

246th National Meeting (2013)

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