Determination of manganese superoxide dismutase activity by direct spectrophotometry.
A method to determine Mn-superoxide dismutase activity by measuring directly the rate of decay of O2- in a spectrophotometer, is described. Decay of O2- generated by KO2 at pH 9.5, was monitored as the fall in absorbance (A250nm-A360nm). Mn-superoxide dismutase was determined as the activity of cyanide-resistant superoxide dismutase, calculated from the rate of O2- dismutation. Mn-superoxide dismutase could be determined in the presence of a 700 times higher Cu,Zn-superoxide dismutase activity. The alkaline pH did not cause analytical problems. The assay was used to measure both Mn- and Cu,Zn-superoxide dismutase activity in mitochondrial preparations. The assay had a detection limit of 2.8 ng/ml when Mn-superoxide dismutase from E. coli was used, and the between-day CV was 5.8%. The assay is an alternative to indirect methods for detecting superoxide dismutase activity.
Bolann
B J
BJ
Institute of Clinical Biology, University of Bergen, Norway.
Tangerås
A
A
Ulvik
R J
RJ
D000818:Animals; D002384:Catalysis; D002417:Cattle; D008930:Mitochondria, Liver / Q000201:enzymology; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000378:metabolism*
D013482:Superoxide Dismutase; D010100:Oxygen