Biphenyl-2,3-diol 1,2-dioxygenase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are biphenyl-2,3-diol and oxygen, whereas its two products are 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate and water.
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 biphenyl-2,3-diol:oxygen 1,2-oxidoreductase (decyclizing). Other names in common use include 2,3-dihydroxybiphenyl dioxygenase, and biphenyl-2,3-diol dioxygenase. This enzyme participates in gamma-hexachlorocyclohexane degradation and biphenyl degradation.
As of late 2007, 16 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , , , , , , , , and .