Abstract: The Cdna encoding the general odorant binding protein Ⅱ (named as HassGOBP2) was isolated from the male and female antennae of Helicoverpa assulta (Guenée) by reverse transcription polymerase chain reaction (RTPCR). The Cdna fragment was further cloned into PgemT Easy vector, and then constructed into expression vector Pet-30a(+) for overexpression in prokaryotic cells. Structural analysis showed that the full length of mature HassGOBP2 open reading frame (ORF) was 489 bp, encoding 162 amino acid residues; the predicted MW and Pi were 18.2 Kd and 5 35, respectively. The deduced amino acid sequence showed a high identity to the reported sequences of GOBP2 from other insects and shared the typical structural features of odorant binding proteins from other insects. Induced by IPTG, the full length of GOBP2 was expressed in Escherichia coli BL21 (DE3). Its molecular weight was found to be about 23 Kd by checking with SDS polyacrylamide gel electrophoresis and Western blotting.

Key words: Helicoverpa assulta, general odorant binding protein, antenna, gene cloning, prokaryotic expression