Abstract:

The cathepsin B cDNA from ovary of Helicoverpa assulta (Guenée) was cloned by reverse transcription polymerase chain reaction (RT-PCR). The results of cloning and sequencing showed that the full-length open reading frame (ORF) of HassCB is 1 017 bp (registered with GenBank accession no. EF154237), encoding 338 amino acid residues, and the predicted N-terminus hydrophobic region contains 21 amino acid residues displaying the characteristic features of a signal peptide. The predicted molecular weight (MW) and isoelectric point (pI) are 35.5 kDa and 5.96，respectively. The HassCBa gene without signal peptide was then constructed into the expression vector pGEX-4T-1 for expression in prokaryotic cells. The SDS-PAGE and Western blot analysis showed that the HassCB was expressed in Escherichia coliBL21, and the expressed product has the MW of 61 kDa, nearly equal to the predicted. Furthermore, the mice were immunized with recombinant HassCB, and the results indicated that the antibody liter was

Key words: Helicoverpa assulta, cathepsin B, gene cloning, sequence analysis, prokaryotic expression, immunoblotting