LIGHT-INDUCED OXYGEN EVOLUTION CAUSED BY HYDROGEN PEROXIDE IN CATALASE-INHIBITED CHLORELLA CELLS

Abstract

1. Chlorella cells and spinach chioroplasts, whose catalase activity had been more than 90% inhibited by 10⁻⁵M azide, were found to decompose H₂O₂ photochemically to liberate oxygen, indicating that H₂O₂ was used as an oxidant of the HILL reaction.

2. That, however, the observed phenomena cannot be fully accounted for in terms of the HILL reaction with H₂O₂ was revealed by the observation that an extract of Chiorella cells, which had been completely freed from chlorophyll, also showed a light-accelerated O2 evolution from H₂O₂ in the presence of 10⁻5 M azide. This extract contained a large quantity of catalase, which seemed to have been, in some way, involved in the reaction in question.

3. The catalatic H₂O₂ decomposition caused by crystalline catalase of mammalian liver (in the presence of 10⁻⁵M azide) was not accelerated by the effect of light.