Cuprein (Superoxide dismutase) was the higher content of aromatic amino acid residues, isolated from Saccharomyces cerevisiae and bovine The UV extinction coefficients at 259 nm were liver employing organic solvents, gel filtration and £259=9840 for the yeast cuprein and £259=10400 DEAE chromatography. The preparations were for hepatocuprein. Both proteins were of greenishhomogeneous as shown by gel filtration, polyacryl-blue colour and displayed a broad absorption band amide gel electrophoresis and sedimentation ve-at 680 nm and a shoulder at 430 nm. In contrast to locity measurements. The ^20,w value was 3.10S. the hepatocuprein, subunits of mol. wt. 16000 were The metal content of the microbial cuprein (super-obtained after treating the yeast cuprein with urea oxide dismutase) was identical with that of the and sodium dodecylsulphate and in the absence of mammalian type cuprein and comprised approx. 2 g disulphide reducing agents. From CD measureatoms of copper and of zinc per mol of protein. The ments it was concluded that the -helical content molecular weight of the yeast enzyme was 31200 of both cupreins was very low. Cotton effects were compared to 32500 of the hepatic enzyme. The UV observed at 208 nm for hepatocuprein and at 212 nm absorption spectrum of bovine hepatocuprein was for the yeast cuprein. Some differences of the EPR superimposable upon that of bovine erythrocuprein. parameters between both cupreins were determined. However, the UV spectrum of the yeast cuprein However, the Superoxide dismutase activity was displayed an increased absorption in the 280 nm almost identical using either cuprein. region ( ·28 = 9600) which could be attributed to Mikrobielles Cuprein und Hepatocuprein: Isolierung und Charakterisierung von Cuprein (Superoxid-Dismutase) aus Saccharomyces cerevisiae und aus RinderleberZusammenfassung: Cuprein (Superoxid-Dismutase) Filtration an Sephadex G-75 und DEAE-23 Chrowurde aus Saccharomyces cerevisiae und Rinder-matographie) isoliert. Die grünblauen Cu-Zn-Proleber unter Verwendung von organischen Lösungs-teine waren homogen, was durch Gel-Filtration, mittein (Äthanol, Chloroform und Aceton) sowie Polyacrylamid-Gel-Elektrophorese sowie Sedimenzusätzlicher chromatographischer Schritte (Gel-tations-Geschwindigkeitsanalysen ermittelt wurde. Enzymes:Catalase, hydrogen-peroxide:hydrogen-peroxide oxidoreductase (EC 1.11.1.6) Xanthine oxidase, xanthine: oxygen oxidoreductase (EC 1.2.3.2). Abbreviations: CD = circular dichroism; EPR = electroparamagnetic resonance.