Catalase is a tetrameric iron porphyrin that catalyses the dismutation of H2O2 to water and oxygen. The Arabidopsis genome encodes three catalase subunits, CAT1 (At1g20630) , CAT2 (At4g35090) , and CAT3 (At1g20620) . These three individual subunits associate to form at least six catalase isoforms.
