<p>The KduI/IolB family of enzymes includes 5-keto 4-deoxyuronate isomerase (KduI) and 5-deoxy-glucuronate isomerase (IolB). </p><p>KduI is involved in pectin degradation by free-living soil bacteria that use pectin as a carbon source, breaking it down to 2-keto-3-deoxygluconate, which can ultimately be converted to pyruvate. KduI catalyses the fourth step in pectin degradation, namely the interconversion of 5-keto-4-deoxyuronate and 2,5-diketo-3-dexoygluconate [<cite idref="PUB00014561"/>]. KduI has a TIM-barrel fold [<cite idref="PUB00038353"/>].</p><p> IolB is one of several bacterial proteins encoded by the inositol operon (iolABCDEFGHIJ) in <taxon tax_id="1423">Bacillus subtilis</taxon> that are involved in myo-inositol catabolism. The enzyme is responsible for isomerization of 5-deoxy-D-glucuronic acid by IolB to produce 2-deoxy-5-keto-D-gluconic acid [<cite idref="PUB00053908"/>]. IolBs possess a cupin-like structure.</p>