Polarographic assay and intracellular distribution of superoxide dismutase in rat liver.

摘要: 1. A polarographic assay of superoxide (O2--) dismutase (EC 1.15.1.1) activity is described, in which the ability enzyme to inhibit O2---dependent sulphite oxidation, initiated by xanthine oxidase activity, measured. The was used a study intracellular distribution rat liver. Both cyanide-sensitive cupro-zinc (92% total activity) and cyanide-insensitive mangano-dismutase (8%) were 2. Rat liver homogenates contained both particulate (16%y soluble (84%) activity. types dismutase, whereas nearly all enzymes. pattern similar that cytochrome glutamate dehydrogenase, indicating probably present exclusively mitochondria. 3. Superoxide heavy-mitochondrial (M) fraction latent activated severalfold largely solubilized sonication. Treatment M with digitonin or hypo-osmotic suspending medium indicated most located mitochondrial intermembrane space, mangano-enzyme inner-membrane matrix space. 4. small amount appeared be nuclei microsomal fraction, but little no lysosomes peroxisomes. 5. results are discussed relation location known O2---generating enzymes, possible role H2O2 formation, current views on physiological function enzyme.