PHOTOINACTIVATION OF CATALASES FROM MAMMAL LIVER, PLANT LEAVES AND BACTERIA. COMPARISON OF INACTIVATION CROSS SECTIONS AND QUANTUM YIELDS AT 406 nm

Abstract— Photoinactivation in vitro at pH 7.0 of catalases from different sources (bovine liver, spinach leaves, and Micrococcus lysodeikticus) was studied. The wavelength of the inactivating light was close to the Soret peak of catalase. No great difference in light sensitivity between soluble catalases were found; the inactivation cross sections found ranged from 3.8.10^-4 to 5.0. 10^-4Ų/molecule. The inactivation quantum yield is 2.2. 10^-5 for bovine liver catalase and 3.110^-5 for Micrococcus catalase. The quantum yield for soluble spinach catalase is of a similar order of magnitude. There are some indications of a greater resistance to photodestruction of the spinach leaf catalase activity associated with small particles.