Occurs in almost all aerobically respiring organisms and serves to protect cells from the toxic effects of hydrogen peroxide. 2 H2O2 = 2 H2O + O2 Homotetramer and heterotetramer (PubMed:25700484). At least six or seven isozymes are produced from a mixture of 3 gene products. Interacts with NCA1 (PubMed:25700484). Interacts with LSD1 (PubMed:23958864). A number of isoforms are produced. According to EST sequences. Belongs to the catalase family.