Relaxation activity assay of H139C, Y174C and K524C mutants of MtTOP1. Serial dilutions of purified wild-type MtTOP1 and mutant derivatives with cysteine substitutions at H139, Y174 and K524 were added to 20 μL reaction volume of 10 mM Tris-HCl, pH 8.0, 50 mM NaCl, 0.1 mg/mL gelatin, 6 mM MgCl2 and 0.2 μg of supercoiled plasmid DNA. Incubation was at 37°C for 30 min.
Narula et al. BMC Biochemistry 2010 11:41 doi:10.1186/1471-2091-11-41