Catalase-related immune responsive <p>Catalases (<db_xref db="EC" dbkey="1.11.1.6"/>) are antioxidant enzymes that catalyse the conversion of hydrogen peroxide to water and molecular oxygen, serving to protect cells from its toxic effects [<cite idref="PUB00012765"/>]. Hydrogen peroxide is produced as a consequence of oxidative cellular metabolism and can be converted to the highly reactive hydroxyl radical via transition metals, this radical being able to damage a wide variety of molecules within a cell, leading to oxidative stress and cell death. Catalases act to neutralise hydrogen peroxide toxicity, and are produced by all aerobic organisms ranging from bacteria to man. Most catalases are mono-functional, haem-containing enzymes, although there are also bifunctional haem-containing peroxidase/catalases (<db_xref db="INTERPRO" dbkey="IPR000763"/>) that are closely related to plant peroxidases, and non-haem, manganese-containing catalases (<db_xref db="INTERPRO" dbkey="IPR007760"/>) that are found in bacteria [<cite idref="PUB00015054"/>].</p><p>This entry represents a small conserved region within catalase enzymes. This domain carries the immune-responsive amphipathic octa-peptide that is recognised by T cells [<cite idref="PUB00044744"/>].</p>