Abstract: Carboxylesterases are associated with insecticide-resistance and play an important role in the detoxification of many agrochemicals. Using the polyclonal antiserum against Trichoplusia ni (Hübner) invertebrate intestinal mucin (IIM), a carboxylesterase gene SeC1 was screened from the cDNA expression library of Spodoptera exigua (Hübner) midgut. The full-length of SeC1 is 1 812 bp(GenBank accession no. EF580101), and the open reading frame encodes 535 amino acids. The SeC1 possesses a catalytic triad, consisting of a Ser, a His and a Glu residue (Ser186, His443 and Glu319), which is characterized by carboxylic esters (EC: 3.1.1.-). The SeC1 gene has been recombined into pQE30 vector. The spot blot analysis demonstrated that SeC1 protein was expressed at a low level after being induced by IPTG. The activity for Sec1 was 1.3 nmol/100 μL enzyme buffer with the α-NA as substrate.

Key words: Spodoptera exigua, cDNA expression library, carboxylesterase, expression, spot-blot analysis