The properties of the secondary catalase—peroxide complex (Compound II) in the hemoglobin-free perfused rat liver

The possibility of the occurrence of the secondary catalase-peroxide complex (Compound II) in the isolated peroxisomal-mitochondrial fraction of rat liver and in the perfused rat liver has been examined under various conditions. The steady state of Compound I is maintained by either an endogeneous or a urate and glycolate-supplemented H₂O₂ generation in both systems, but Compound II is not detectable. Significant accumulation of Compound II, which is identified by the measurement of its difference spectrum and by its response to hydrogen donors, is observed only when Compound I is converted to Compound II by an appropriate concentration of p-cresol. The properties of Compound II observed in the perfused liver are similar to those observed with isolated catalase.