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Metabolism and Enzymology

Superoxide Dismutase Activity in Needles of Norwegian Spruce Trees (Picea abies L.) ¹

Fraunhofer Institut für Atmosphärische Umweltforschung, Kreuzeckbahnstr. 19, D-8100 Garmisch-Partenkirchen, Federal Republic of Germany, Botanisches Institut der Universität zu Köln, Gyrhofstr. 15, D-5000 Köln 41, Federal Republic of Germany

The activity of superoxide dismutase was investigated in needles of spruce trees. To obtain maximum activity, needles were homogenized in the presence of Triton X-100 and polyvinylpyrrolidone. Superoxide dismutase activity was measured in dialyzed extracts with a modified epinephrine assay (HP Misra, I Fridovich [1972] J Biol Chem 247: 3170-3175) at pH 10.2. The extracts contained 70 to 120 units of superoxide dismutase per milligram protein. One unit of superoxide dismutase was completely inhibited in the presence of 20 micromolar NaCN. On native polyacrylamide gels three electromorphs were visualized after staining for activity. All three species were sensitive to CN^– and H₂O₂ and were therefore assumed to be Cu/Zn-superoxide dismutases. Superoxide dismutase activity was dependent on the age of the needles and declined by approximately 25% within 3 to 4 years.