The enzyme 4-carboxymuconolactone decarboxylase (EC 4.1.1.44) catalyzes the chemical reaction

2-carboxy-2,5-dihydro-5-oxofuran-2-acetate 4,5-dihydro-5-oxofuran-2-acetate + CO₂

This enzyme belongs to the family of lyases, specifically the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is 2-carboxy-2,5-dihydro-5-oxofuran-2-acetate carboxy-lyase (4,5-dihydro-5-oxofuran-2-acetate-forming). Other names in common use include gamma-4-carboxymuconolactone decarboxylase,^{[citation needed]} and 4-carboxymuconolactone carboxy-lyase.^{[citation needed]} This enzyme participates in benzoate degradation via hydroxylation.

As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 2AF7.

• Ornston LN (August 1966). "The conversion of catechol and protocatechuate to beta-ketoadipate by Pseudomonas putida. 3. Enzymes of the catechol pathway". The Journal of Biological Chemistry. 241 (16): 3795–9. doi:10.1016/S0021-9258(18)99841-8. PMID 5330966.
• Ornston LN (1970). "Conversion of catechol and protocatechuate to β-ketoadipate (Pseudomonas putida)". Conversion of catechol and protocatechuate to beta-ketoadipate (Pseudomonas putida). Methods Enzymol. Vol. 17A. pp. 529–549. doi:10.1016/0076-6879(71)17237-0. ISBN 978-0-12-181874-6.