A simple colorimetric method for detection of isocarbophos was developed based on the enhanced peroxidase-like activity of hemin. Hemin could catalyze the oxidation of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2, which made TMB to lose one electron and caused reaction solution color changing from initial transparent to blue-green. Adding isocarbophos improved hemin affinity to substrates, which further enhanced peroxidase-like activity of hemin and made TMB to lose two electrons. The color of TMB solution was further changed from blue-green to yellow, and the degree of color change was proportional to the concentration of isocarbophos. Under the optimal conditions, the present analytical method for isocarbophos detection had a dynamic range from 2 μg/L to 100 μg/L with a detection limit of 1.2 μg/L (3σ). The selectivity assay demonstrated that other organophosphorus pesticides exhibited negligible interferences for isocarbophos detection. The application of the proposed method in the practical samples showed that the mean recovery of isocarbophos was in the range of 94.4％-113.0％, thus it could be widely applied to rapidly and sensitively detect isocarbophos in the agricultural products.

Objective: To construct eukaryotic expression vector of adenovirus type 5 fiber gene and investigate its expression in eukaryotic cell. Methods: By endonuclease digestion, fragment harboring the fiber gene was cloned into plasmid pBluescript M13- from the pAdEasy-1 to construct pBS/Fiber. The pBS/Fiber was then digested with XbaI and KpnI. The yielding fragment was subcloned into the pcDNA3.1, obtaining the eukaryotic expression vector pcDNA/Fiber. To test the eukaryotic expression ability of the pcDNA/Fiber, pcDNA/Fiber was transiently transduced into the COS-7 cells using lipofectamine, and the fiber protein was detected by SDS-PAGE and Western blot. Results: Both plasmid pcDNA3 1 and eukaryotic expression vector pcDNA/Fiber were successfully constructed. Anew protein band was detected by SDS-PAGE and Western blot, its molecular weight was 62 kD on denaturing SDS-PAGE gel and 186 kD on non-denaturing SDS-PAGE gel.Conclusions: The eukaryotic expression vector of the adenovirus type 5 fiber gene was expressed in the COS-7 cells. In natural state, the expressed fiber protein was a trimer. The plasmid pBS/Fiber can be used to construct target adenovirus vector.