11] Catalase modification as a marker for singlet oxygen

Abstract

Most aerial organisms have a typical catalase, along with catalase peroxidases and peroxidases. Typical catalases are a conserved family of proteins, sharing over 35% amino acid identity from bacteria to humans. Catalase is one of the most active enzymes known and is usually stable. Because of this, its activity can be detected readily and the enzyme is purified easily. Catalases from bacteria, fungi, plants, and animals are oxidized by 1 O 2 , giving rise to more acidic, fully active conformers. Total cell extracts can be analyzed by gel electrophoresis to detect the catalase mobility shift caused by 1 O 2 . The oxidation of catalase is specific for 1 O 2 and is probably due to heme modification. An electrophoretic mobility shift of catalase from cells induced to differentiate or subjected to stress conditions could be indicative of 1 O 2 . Catalase modification can be increased or decreased according to the amount of effectively quenching carotenoids in the cell. A purified catalase can also serve as a marker to detect in vitro generation of 1 O 2 .