2-pyrone-4,6-dicarboxylate Lactonase

In enzymology, 2-pyrone-4,6-dicarboxylate lactonase (EC 3.1.1.57) is an enzyme that catalyzes the reversible hydrolytic chemical reaction

2-pyrone-4,6-dicarboxylate + H₂O 4-carboxy-2-hydroxyhexa-2,4-dienedioate and 4-oxalomesaconate

Thus, the two substrates of this enzyme are 2-pyrone-4,6-dicarboxylate and H₂O, whereas its product is a tautomeric mixture of 4-oxalomesaconate and 4-carboxy-2-hydroxymuconate.

This enzyme belongs to the Amidohydrolase superfamily of enzymes and is a member of Cluster of Orthologous Groups (COG) 3618. The systematic name of this enzyme is 2-pyrone-4,6-dicarboxylate lactonase but is also known as LigI. This enzyme is found to play an important role in the metabolism of lignin-derived aromatic compounds in both the syringate degradation pathway and the protocatechuate 4,5-cleavage pathway.

LigI from Sphingomonas is of particular interest as it has been shown to be the first member of the amidohydrolase superfamily to not require a divalent metal cation for catalytic activity.