1 ml protein solution
was added to 4 ml Tris buffer (0.1 M, pH 8.0) containing 1 M urea
0.01 M EDTA and 0.05 ml of 102 M DTNB (5,59-dithiobis-2-
nitrobenzoic acid) solution, and then the absorbance of the mixture
was measured at 412 nm after incubation for 20 min at ambient
temperature. T