In enzymology, a 3-carboxyethylcatechol 2,3-dioxygenase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are 3-(2,3-dihydroxyphenyl)propanoate and O<sub>2</sub>, whereas its product is 2-hydroxy-6-oxonona-2,4-diene-1,9-dioate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O<sub>2</sub> as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O<sub>2</sub>. The systematic name of this enzyme class is 3-(2,3-dihydroxyphenyl)propanoate:oxygen 1,2-oxidoreductase (decyclizing). Other names in common use include 2,3-dihydroxy-beta-phenylpropionic dioxygenase, 2,3-dihydroxy-beta-phenylpropionate oxygenase, and 3-(2,3-dihydroxyphenyl)propanoate:oxygen 1,2-oxidoreductase. This enzyme participates in phenylalanine metabolism. It employs one cofactor, iron.