In degradation studies, the absorbance of the dye at 618 nm (25 mg CSB/l) was monitored against a heat treated blank. The rate of decolorization was initially linear (0.82-25 mg protein), and proportional to enzyme concentration but equilibrium was reached after 2h. The major CSB peak at 618 nm and minor peak at 320 nm disappeared and a new peak appeared at 550 nm.
The dye had a retention time of 22min on HPLC (C18 reversed phase column) (Schliephake et al. 2000). After 20 h reaction time the 22 min peak disappeared and two new peaks appeared with retention times of 1.28 and 3.96 min, respectively. Their molar absorptivities were an order of magnitude lower than CSB. Thus, the disazo dye CSB had been clearly degraded by the activity of the laccase. The products have not been characterized so far.
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