D. Frear, G. Still
Jun 1, 1968
Citations
5
Influential Citations
109
Citations
Quality indicators
Journal
Phytochemistry
Abstract
Abstract An aryl acylamidase (aryl-acylamine amidohydrolase, EC 3.5.1.a) from rice, which hydrolyzes 3,4-dichloropropionanilide, has been partially purified and characterized. The distribution of the enzyme in rice and barnyard grass tissues was determined. The enzyme displayed a broad specificity for chlorinated ring-substituted propionanilide analogs, but was specific for 3,4-dichloropropionanalide when compared with several alkyl substituted analogs. The enzyme was inhibited by sulfhydryl reagents and was strongly inhibited at 1·0 × 10 −6 M by the insecticidal carbamates 1-naphthylmethylcarbamate,4-benzothienyl methylcarbamate, 2-chloro-4,5-xylyl methylcarbamate, 2,4,5-trimethylphenyl methylcarbamate, 3,4,5-trimethylphenyl methylcarbamate and 4-(methylthiol) 3,5-xylyl methylcarbamate. The partially purified enzyme had a broad pH optimum between 7·5 and 7·9, with an apparent K m of 2·93 × 10 −3 M for 3,4-dichloropropionanilide. The K i for 1-naphthyl methylcarbamate was 1·51 × 10 −8 M with 3,4-dichloropropionanilide as the substrate. The significance of the enzyme distribution in the resistant and susceptible species and the inhibition of the rice enzyme by insecticidal carbamates is discussed.