Spectrophotometric Assay for Superoxide Dismutase Based on Tetrazolium Salt 3′-{1-[(Phenylamino)-carbonyl]-3,4-tetrazolium}-bis(4-methoxy-6-nitro)benzenesulfonic Acid Hydrate Reduction by Xanthine–Xanthine Oxidase
✍ Scribed by Hiroyuki Ukeda; Susumu Maeda; Toshinao Ishii; Masayoshi Sawamura
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 88 KB
- Volume
- 251
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
XTT (3'-{1-[(phenylamino)-carbonyl]-3, 4-tetrazolium}bis(4-methoxy-6-nitro)benzenesulfonic acid hydrate) was reduced to a water-soluble product with an absorbance maximum at about 470 nm by superoxide anion generated by xanthine-xanthine oxidase (XO). The rate of XTT reduction was linearly related to XO activity and the reduction was inhibited by superoxide dismutase (SOD). A perfect inhibition of the reduction of XTT by SOD was achieved, suggesting that XTT does not interact with XO. The present XTT-based assay had a higher sensitivity than a conventional nitroblue tetrazolium-based assay by a factor of 2.5 at pH 10.2. This method was applicable to the SOD assay in the pH range 8.0-10.2.