Bifunctional enzyme with both catalase and broad-spectrum peroxidase activity. May play a role in the intracellular survival of mycobacteria. AH2 + H2O2 = A + 2 H2O 2 H2O2 = 2 H2O + O2 Binds 1 heme b (iron(II)-protoporphyrin IX) group per dimer. Homodimer. Formation of the three residue Trp-Tyr-Met cross-link is important for the catalase, but not the peroxidase activity of the enzyme. Belongs to the peroxidase family. Peroxidase/catalase subfamily.