Abstract: The LASI gene was ligated into different vectors to construct recombinant prokaryotic expression plasmids. Expressed conditions of LASI gene were subsequently optimized via three aspects inducing time, IPTG concentration and inducing temperature. The results indicated that pET28a was a suitable expression vector for LASI. The optimal conditions for expression of pET28a-LASI were inducing time of 8 hours, IPTG at concentration of 1.0 mmol/L, and inducing temperature of 27 ℃. The solubility assay indicated that in optimal conditions, part of the LASI recombinant protein exists in soluble form and the recombinant protein could specifically bind to the HIS-tagged monoclonal antibody. The purified LASI was capable of inhibiting the activities of porcine amylase and achieving the ultimate inhibition rate in 34%. In this study, the expression conditions of LASI recombinant protein were optimized, and a amount of LASI recombinant protein was obtained. Therefore, this work laid the foundation for further study on the function of LASI.

Key words: Ligusticum chuanxiong, α-amylase inhibitor, prokaryotic expression, condition optimization