In vitro, is able to reduce the standard aldo-keto reductase (AKR) substrates DL-glyceraldehyde, D-erythrose and methylglyoxal in the presence of NADPH, albeit with poor efficiency. Shows only trace activity with benzaldehyde and butyraldehyde. Is unable to oxidize myo-inositol with either NADP(+) or NAD(+) as a cosubstrate and also does not use glucose, 2-pyridine carboxyaldehyde, fructose, xylose and succinyl semialdehyde as a substrate (PubMed:12554958, PubMed:15019785). The physiological function of this enzyme is not clear (PubMed:15019785). Does not seem to be necessary for inositol catabolism (PubMed:9226270). kcat is 2.07 sec(-1) with DL-glyceraldehyde as substrate. kcat is 2.97 sec(-1) with D-erythrose as substrate. Monomer. Induced by inositol (PubMed:9226270). Repressed by glucose (PubMed:11160890). Is cotranscribed with iolR, the repressor of the iol operon (PubMed:9226270). Disruption of this gene affects neither growth on inositol nor the inducibility and catabolite repression of Idh synthesis. The 3D-structure shows a unique architecture for an AKR active site, which may explain the low catalytic power. Belongs to the aldo/keto reductase family. Aldo/keto reductase 11 subfamily.