What is "carboxymethylenebutenolidase"

In enzymology, a carboxymethylenebutenolidase is an enzyme that catalyzes the chemical reaction

4-carboxymethylenebut-2-en-4-olide + HO $\rightleftharpoons$ 4-oxohex-2-enedioate

Thus, the two substrates of this enzyme are 4-carboxymethylenebut-2-en-4-olide and HO, whereas its product is 4-oxohex-2-enedioate.

This enzyme belongs to the family of hydrolases, specifically those acting on carboxylic ester bonds. The systematic name of this enzyme class is 4-carboxymethylenebut-2-en-4-olide lactonohydrolase. Other names in common use include maleylacetate enol-lactonase, dienelactone hydrolase, and carboxymethylene butenolide hydrolase. This enzyme participates in gamma-hexachlorocyclohexane degradation and 1,4-dichlorobenzene degradation.