The reaction system includes 0.1 M Gly-NaOH buffer and the supernatant of the homogenate of the grass carp and common carp liver representing the enzyme solution. After addition of CCU, the reaction mixture was incubated at 25 degree C for 5h. The metabolite was extracted with ethyl acetate, separated by TLC and identified by HPLC. It was demonstrated that CPU was produced in the mixture. That the product was CPU was further verified by spectroscopy, using a special UV detector which could give absolute spectral evidence for the identification of CCU metabolite, and comparing the UV scanning chromatograph for CPU standard with that of the metabolite spot at the certain range of wavelengths. When specific inhibitor of esterase was applied to the reaction mixture the activity of enzyme was decreased by 89 apprx 99 percent. It shows the key role of esterase in the production of CPU.
