N-terminal catalytic domain of catalase-peroxidases.
This is a subgroup of heme-dependent peroxidases of the plant superfamily that share a heme prosthetic group and catalyze a multistep oxidative reaction involving hydrogen peroxide as the electron acceptor. Catalase-peroxidases can exhibit both catalase and broad-spectrum peroxidase activities depending on the steady-state concentration of hydrogen peroxide. These enzymes are found in many archaeal and bacterial organisms, where they neutralize potentially lethal hydrogen peroxide molecules generated during photosynthesis or stationary phase. Along with related intracellular fungal and plant peroxidases, catalase-peroxidases belong to class I of the plant peroxidase superfamily. Unlike the eukaryotic enzymes, they are typically comprised of two homologous domains that probably arose via a single gene duplication event. The heme binding motif is present only in the N-terminal domain; the function of the C-terminal domain is not clear.
Comment:The enzyme is a dimer of two identical subunits; each subunit is composed of two structurally homologous domains with a topology similar to that of class I peroxidase. The active site is in the N-terminal domain.
Comment:Active site includes heme-binding residues; these structures do not have substrate bound.
Structure:1ITK: Haloarcula marismortui catalase peroxidase; contacts at 4.0A - View structure with Cn3D