Distribution and properties of triazophos-degrading enzyme

To investigate the effects of different fractions of bacterial strain Bacillus TAP-1 on the degradation rate of tirazophos, sonication method was applied to lyse the TAP-1 cells to obtain triazophos-degrading enzyme， while HPLC（High Performance Liquid Chromatography） method was used to determine the enzymatic properties. The results showed that the degradation rate of triazophos by intracellular, intercellular and extracellular extracts were 84.4（±6.71）%, 12.8（±2.44）%, and 2.8（±0.34）%, respectively. The active substances of triazophos-degrading were intracellular fractions. The enzyme demonstrated greatest enzymatic activity in the pH range of 6.5-7.0 with its highest activity occurring in the pH range of 5.0-7.5. Enzymatic activity occurred at an optimum temperature of 30℃ for the degradation of triazophos；activity remained above 75% of the maximum over a temperature range of 25℃-40℃. Different chemicals and metallic ions also had different effects on its activity. Its activity can be strongly inhibited by thiol modifier, ETDA, Hg2+ and Mn2+, but stimulated by Mg2+，Co2+ and Fe3+. The Km value and the maximal degradation rate of triazophos-hydrolase were 23.02 μmol/L and 0.738 μmol/mg·min, respectively.