Purification and Properties of a Phenylcarbamate Herbicide Degrading Enzyme of Pseudomonas alcaligenes Isolated from Soil

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A phenylcarbamate degrading enzyme was isolated from Pseudomonas alcaligenes. The enzyme was purified to a specific activity of 119U/mg by ammonium sulphate precipitation, gel filtration, DEAE and hydroxy-apatite chromatographies. The purified enzyme was found to be homogeneous on SDS polyacrylamide gel electrophoresis. The molecular weight was estimated to 68, 000. The pH optimum was around 9.5 and the temperature optimum was 28°C. The Km for CIPC was 1.19 × 10^-5M. Hg²⁺, PMSF inhibited the enzyme, but thiol reagents and EDTA had no effect. The enzyme degraded a number of phenylcarbamate herbicides (CIPC, BIPC, IPC and swep) and propanil but did not hydrolyse barban and carbetamide, which are phenylcarbamates, or monuron and linuron, which are phenylureas. The enzyme is probably an amidase.