The Class III extradiol dioxygenase, 4,5-DOPA Dioxygenase, catalyzes the incorporation of both atoms of molecular oxygen into 4,5-dihydroxy-phenylalanine.
This subfamily is composed of plant 4,5-DOPA Dioxygenase, the uncharacterized Escherichia coli protein Jw3007, and similar proteins. 4,5-DOPA Dioxygenase catalyzes the incorporation of both atoms of molecular oxygen into 4,5-dihydroxy-phenylalanine (4,5-DOPA). The reaction results in the opening of the cyclic ring between carbons 4 and 5 and producing an unstable seco-DOPA that rearranges to betalamic acid. 4,5-DOPA Dioxygenase is a key enzyme in the biosynthetic pathway of the plant pigment betalain. Homologs of DODA are present not only in betalain-producing plants but also in bacteria and archaea. This enzyme is a member of the class III extradiol dioxygenase family, a group of enzymes which use a non-heme Fe(II) to cleave aromatic rings between a hydroxylated carbon and an adjacent non-hydroxylated carbon.