2-hydroxymuconic semialdehyde hydrolase PIRSF037174. 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 (environmental pollutants: BP/PCB). 2-hydroxy-6-oxononadienedioate/2-hydroxy-6-oxononatrienedioate hydrolase catalyzes the cleavage of the C5-C6 bond of 2-hydroxy-6-oxononadienedioate and 2-hydroxy-6-oxononatrienedioate, a dienol ring fission product of the bacterial meta-cleavage pathway for degradation of phenylpropionic acid. The purified enzyme is a dimeric protein requiring no cofactors for catalytic activity