Book chapter
[61] Assay of superoxide dismutase activity in tumor tissue
Methods in Enzymology, pp.457-464
Elsevier Science & Technology
1984
DOI: 10.1016/S0076-6879(84)05064-3
PMID: 6547201
Abstract
This chapter describes the assay for the measurement of superoxide dismutase (SOD) activity which differs from the commonly used nitroblue tetrazolium (NBT)/cytochrome c SOD assays in the following ways. First of all, diethylenetriaminepentaacetic acid (DETAPAC) is used instead of ethylenediamine tetraacetic acid (EDTA). DETAPAC makes the SOD assay more sensitive, probably because Fe-DETAPAC does not react with O2·-, whereas Fe-EDTA does. Second, catalase is always included in present assay mixture, whereas most commonly used assays do not. Catalase is for two reasons: (1) H2O2 inhibits and even inactivates Cu,Zn-SOD, so the removal of H2O2 is necessary for preventing this inhibition and (2) for kinetic reasons, the assay should be run with the product (H2O2) as low as possible, so that the equilibrium will not be shifted in favor of O2·- production. In the assay procedure, varying concentrations of SOD activity are added until maximum inhibition is obtained. One unit of activity is that amount of protein that gives half-maximal inhibition. This assay differs from that of the cytochrome c method in that 95–100% inhibition is usually not achieved. With pure enzyme, 80–90% inhibition is obtained, whereas with most tissue homogenates, 70–80% inhibition is observed. This is why half-maximal inhibition is used rather than 50% inhibition as in the cytochrome c assay.
Details
- Title: Subtitle
- [61] Assay of superoxide dismutase activity in tumor tissue
- Creators
- Larry W. OberleyDouglas R. Spitz
- Resource Type
- Book chapter
- Publication Details
- Methods in Enzymology, pp.457-464
- Publisher
- Elsevier Science & Technology
- DOI
- 10.1016/S0076-6879(84)05064-3
- PMID
- 6547201
- eISSN
- 1557-7988
- ISSN
- 0076-6879
- Language
- English
- Date published
- 1984
- Academic Unit
- Pathology; Radiation Oncology; Fraternal Order of Eagles Diabetes Research Center
- Record Identifier
- 9984313089702771
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