5-keto-L-gluconate epimerase

UniProtKB accession:  Q9WYP7

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UniProtKB description:  Catalyzes the reversible epimerization between 5-keto-L-gluconate (5-dehydro-L-gluconate) and D-tagaturonate, and thus probably functions in a myo-inositol degradation pathway together with IolG, IolM and IolN (PubMed:23441918). Is not active on the enantiomer 5-keto-D-gluconate (PubMed:23441918). Was also shown to be a nonphosphorylated sugar isomerase with broad substrate specificity in vitro (PubMed:28258150). Is able to catalyze the reversible C3-epimerization of L-ribulose to L-xylulose, D-ribulose to D-xylulose, D-psicose to D-fructose, and D-tagatose to D-sorbose, with a substrate preference for ketopentoses rather than ketohexoses (PubMed:28258150). Also catalyzes the aldose-ketose isomerization reaction from either D-erythrose or D-threose to D-erythrulose (PubMed:28258150). Exhibits no activity for C4-epimerization of D-tagatose to D-fructose (PubMed:28258150).