Protocatechuate 3,4-dioxygenase (3,4-PCD) , beta subunit. 3,4-PCD catalyzes the oxidative ring cleavage of 3,4-dihydroxybenzoate to produce beta-carboxy-cis,cis-muconate. 3,4-PCDs are large aggregates of 12 protomers, each composed of an alpha- and beta-subunit and an Fe3+ ion bound in the beta-subunit at the alpha-subunit-beta-subunit interface. 3,4-PCD is a member of the aromatic dioxygenases which are non-heme iron intradiol-cleaving enzymes that break the C1-C2 bond and utilize Fe3+.
Jiyao W et al.(2023). "The conserved domain database in 2023.",