Involved in the reversible interconverion of 2-keto-myo-inositol (2KMI, inosose or 2,4,6/3,5-pentahydroxycyclohexanone) to 1-keto-D-chiro-inositol (1KDCI or 2,3,5/4,6-pentahydroxycyclohexanone). scyllo-inosose = scyllo-inosine Binds 1 divalent metal cation per subunit. Can use Mn(2+), Fe(2+) or Co(2+). Polyol metabolism; myo-inositol degradation into acetyl-CoA. Belongs to the IolI family.