Detoxification of organophosphate pesticides using a nylon based immobilized phosphotriesterase fromPseudomonas diminuta
- Cite this article as:
- Caldwell, S.R. & Raushel, F.M. Appl Biochem Biotechnol (1991) 31: 59. doi:10.1007/BF02922126
A partially purified phophostriesterase was successfully immobilized onto nylon 6 and 66 membranes, nylon 11 powder, and nylon tubing. Up to 9000 U of enzyme activity was immobilized onto 2000 cm2 of a nylon 6 membrane where 1 U is the amount of enzyme necessary to catalyze the hydrolysis of 1.0 μmol of paraoxon/min at 25°C. The nylon 66 membrane-bound phosphotriesterase was characterized kinetically where the apparentKm value for the immobilized enzyme was 0.35 mM. This is 5-6 times higher than that observed for the soluble enzyme. However, nylon immobilization limited the maximum rate of paraoxon hydrolysis to less than 10% of the value measured for the soluble enzyme. The addition of the cosolvent, methanol, resulted in an increase in the apparentKm value for paraoxon hydrolysis but concentrations up to 40% had no negative effect on the catalytic effectiveness with the soluble or immobilized phosphotriesterase. Based on the kinetic analysis, methanol appears to be a competitive inhibitor for both forms of enzyme. The nylon powder immobilized enzyme was shown to be stable for at least 20 mo. The immobilization of the phosphotriesterase onto nylon provides a practical method for the detoxification of organophosphate pesticides.