Demonstration by 2H ENDOR spectroscopy that myo-inositol binds via an alkoxide bridge to the mixed-valent diiron center of myo-inositol oxygenase

myo-Inositol oxygenase (MIOX) is a non-heme diiron oxygenase that cleaves cyclohexane-(1,2,3,5/4,6-hexa)-ol (myo-inositol, MI) to d-glucuronate. Here, we use 2H ENDOR spectroscopy to demonstrate that MI binds to the diiron(II/III) cofactor of MIOX via an alkoxide bridge, most likely involving O1. Analysis shows that MI adopts a symmetrical geometry in which the O-C-2H plane of the bridge is approximately orthogonal to the Fe-O-Fe plane.