In enzymology, toluene dioxygenase () is an enzyme that catalyzes the chemical reaction
The four substrates of this enzyme are toluene, reduced nicotinamide adenine dinucleotide (NADH), oxygen, and a proton. Its products are (1S,2R)-3-methylcyclohexa-3,5-diene-1,2-diol and reduced NAD<sup>+</sup>.
This enzyme is an oxidoreductase, that uses molecular oxygen as oxidant and incorporates both its atoms into the starting material. The systematic name of this enzyme class is toluene,NADH:oxygen oxidoreductase (1,2-hydroxylating). This enzyme is also called toluene 2,3-dioxygenase. It is an ironâÂÂsulfur protein that uses flavin adenine dinucleotide as a cofactor and participates in toluene and xylene degradation.