Studies on peroxisomes III. Further studies on the intraparticulate localization of peroxisomal components in the liver of the rat

The peroxisome-rich fraction prepared from rat liver homogenate was treated by various procedures and the behavior of the peroxisomal core on sucrose density gradient centrifugation was investigated.Peroxisomes were destroyed by various treatments, such as pH 9.0, VirTis blender, sonication and deoxycholate, resulting in the solubilization of catalase from the particles. Urate oxidase was not solubilized at all such treatments. Although D-amino acid oxidase was solubilized by treatments with deoxycholate and VirTis blender, this enzyme was found to be resistant to solubilization by treatment with pH 9.0 or sonication, in contrast to catalase.When the peroxisomal core was investigated, using urate oxidase activity as a marker, its density proved to be changed when submitted to various treatments. These results indicated that the peroxisomes consist of four compartments: a catalase-containing compartment (matrix), a urate oxidase containing compartment (core), a D-amino acid oxidase containing compartment and a low density compartment which is proposed for the first time in the present paper. Furthermore, it was also found that the last two compartments seem to be bound to the core, though the binding might be weak.