Abstract: Carboxypeptidase A (CPA) plays an important role in the digestion of dietary proteins in insects. LstiCPA, a full-length cDNA clone encoding carboxylesterase was obtained by screening cDNA expression library of the midgut of Loxostege sticticalis L. using the polyclonal antiserum against Spodoptera exigua (Hübner) invertebrate intestinal mucin (IIM). LstiCPA is 1 380 bp in length (GenBank accession no. EU924506), and the open reading frame (ORF) encodes 434 amino acids, with the predicted MW 49.1 kDa and pI 9.56. LstiCPA possesses a trypsin cleavage site and a catalytic zinc site characterized by CPA. LstiCPA was recombined into pET30 vector. The Western blotting analysis demonstrated that LstiCPA protein was expressed at a low level after IPTG induction. The enzymatic activity of LstiCPA was 0.0005 U/mL with the FAPP as substrate.

Key words: Loxostege sticticalis, cDNA expression library, carboxypeptidase A, prokaryotic expression