Involved in the recovery of exogenous heme iron. Extracts iron from heme while preserving the protoporphyrin ring intact. Also displays peroxidase activity on guaiacol and catechol in vitro. The deferrochelatase activity appears to be closely related to the peroxidation activity, but the link is unclear. 2 H(+) + heme b = Fe(2+) + protoporphyrin IX Binds 1 heme b (iron(II)-protoporphyrin IX) group non-covalently per subunit. The heme-bound EfeB forms a homodimer whereas the apo-form mainly exists as a monomer. Part of a ferrous iron transporter composed of EfeU, EfeO and EfeB. Predicted to be exported by the Tat system. The position of the signal peptide cleavage has not been experimentally proven. Belongs to the DyP-type peroxidase family. EfeB subfamily.