Bioactivity |
Specific activity is > 90 units/mg, in which one unit will inhibit the rate of reduction of cytochrome c by 50% in a coupled system, using xanthine and Xanthine oxidase at pH 7.8 at 25°C in a 1.5 ml reaction volume. Activity Assay Prepare a 1.5 ml reaction mix into a suitable container and pre-chill on ice before use: The final concentrations are 50mM potassium phosphate, 0.1mM ethylendiaminetetraacetic acid, 0.01mM cytochrome C 0.05mM xanthine, 0.005 units xanthine oxidase. Equilibrate to 25°C and monitor at A550nm until the value is constant using a spectrophotometer. Add 50 ul of recombinant SOD protein in various concentrations (0.5ug, 1ug) in assay buffer. Mix by inversion and record the increase at A550nm for 5 minutes.
|