In enzymology, a dichloromuconate cycloisomerase (EC 5.5.1.11) is an enzyme that catalyzes the chemical reaction

2,4-dichloro-2,5-dihydro-5-oxofuran-2-acetate ${\displaystyle \rightleftharpoons }$ 2,4-dichloro-cis,cis-muconate

Hence, this enzyme has one substrate, 2,4-dichloro-2,5-dihydro-5-oxofuran-2-acetate, and one product, 2,4-dichloro-cis,cis-muconate.

This enzyme belongs to the family of isomerases, specifically the class of intramolecular lyases. The systematic name of this enzyme class is 2,4-dichloro-2,5-dihydro-5-oxofuran-2-acetate lyase (decyclizing). This enzyme participates in 1,4-dichlorobenzene degradation. It employs one cofactor, manganese.