MIOX is the enzyme myo-inositol oxygenase. It catalyses the first committed step in the glucuronate-xylulose pathway, It is a di-iron oxygenase with a key role in inositol metabolism. The structure reveals a monomeric, single-domain protein with a mostly helical fold that is distantly related to the diverse HD domain superfamily. The structural core is of five alpha-helices that contribute six ligands, four His and two Asp, to the di-iron centre where the two iron atoms are bridged by a putative hydroxide ion and one of the Asp ligands. The substrate is myo-inositol is bound in a terminal substrate-binding mode to a di-iron cluster [1]. Within the structure are two additional proteinous lids that cover and shield the enzyme's active site [2].

1: Crystal structure of a substrate complex of myo-inositol oxygenase, a di-iron oxygenase with a key role in inositol metabolism. Brown PM, Caradoc-Davies TT, Dickson JM, Cooper GJ, Loomes KM, Baker EN; Proc Natl Acad Sci U S A. 2006;103:15032-15037. PMID:17012379

2: Structural and biophysical characterization of human myo-inositol oxygenase. Thorsell AG, Persson C, Voevodskaya N, Busam RD, Hammarstrom M, Graslund S, Graslund A, Hallberg BM; J Biol Chem. 2008;283:15209-15216. PMID:18364358