Superoxide Dismutase: Determination of Activity by Inhibition of Photosensitized Chemiluminescence of Glycyltryptophan

E. L. Lozovskaya^* and L. S. Vartanyan

Emmanuel Institute of Biochemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 117977 Russia; fax: (7-095) 137-4101; E-mail: efrem@online.ru

^* To whom correspondence should be addressed.

Received July 8, 1999; Revision received September 14, 1999

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A technique for quantitative determination of superoxide dismutase (SOD) in biological material is described. The technique is based on the riboflavin-photosensitized oxidation of Gly-Trp, which is accompanied by chemiluminescence. Formation of the luminescent product is inhibited by SOD. The dependence of SOD activity on reciprocal intensity of chemiluminescence is linear. The concentration for 50% inhibition is 7.5 ng/ml, and the minimum reliably determined concentration is about 2 ng/ml. The reaction is not sensitive to high concentrations of cyanide, which allows the separate determination of Cu,Zn- and Mn-SOD in mixtures.

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KEY WORDS: superoxide dismutase, quantitative assay, chemiluminescence

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