Involved in the cleavage of the C1-C2 bond of 3D-(3,5/4)-trihydroxycyclohexane-1,2-dione (THcHDO) to yield 5-deoxy-glucuronate (5DG). 3D-3,5/4-trihydroxycyclohexane-1,2-dione + H2O = 5-deoxy-D-glucuronate + H(+) Binds 1 Mg(2+) ion per subunit. Binds 1 thiamine pyrophosphate per subunit. Polyol metabolism; myo-inositol degradation into acetyl-CoA; acetyl-CoA from myo-inositol: step 3/7. Belongs to the TPP enzyme family.