Members of this family are 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase, or HOPD hydrolase, the BphD protein of biphenyl degradation. BphD acts on the product of ring meta-cleavage by BphC. Many species carrying bphC and bphD are capable of degrading polychlorinated biphenyls as well as biphenyl itself.
Jiyao W et al.(2023). "The conserved domain database in 2023.",