2-hydroxymuconate tautomerase (, 4-oxalocrotonate tautomerase, 4-oxalocrotonate isomerase, cnbG (gene), praC (gene), xylH (gene)) is an enzyme with systematic name (2Z,4E)-2-hydroxyhexa-2,4-dienedioate keto-enol isomerase. This enzyme catalyses the following chemical reaction
Involved in the meta-cleavage pathway for the degradation of phenols, modified phenols and catechols.