Recombinant Expression of Sericin Antifreeze Peptide in E.coli and Its Antifreeze Activity

In order to obtain antifreeze peptides efficiently,the recombinant expression of serin antifreeze peptide target gene SerD in E.coli BL21(DE3)was studied,and the antifreeze activity of the expressed product was analyzed subsequently. The gene encoding SerD was synthesized,directionally inserted into vector Pet32a after KpnI and XhoI double enzyme digestion,and constructed the expression vector Pet32a-SerD. Electroporation was converted the expression vector to E.coli BL21(DE3). IPTG induced the expression of target genes,and the target protein was purified by nickel sepharose affinity chromatography. The results indicated that the optimum expression condition was 16 h at 20℃. SDS-PAGE and Western-Blot identified the successful expression of recombinant protein,and the molecular weight of His-SerD fusion protein was between 25~35 kDa. The activity of E.coli expressing His-SerD fusion protein after freezing showed that the growth activity of BL21-SerD expressing His-SerD fusion protein was significantly higher than that of PBL airborne bacteria. The results of recrystallization inhibition activity of His-SerD fusion protein showed that the addition of His-SerD fusion protein could obviously reduce the size of ice crystal particles in the solution,indicated that it had a good recrystallization inhibition activity. This study showed that the recombinant expression system of sericin peptide antifreeze peptide could be successfully constructed in E. coli by genetic engineering method,and the His-SerD fusion protein with antifreezing stress protection could be obtained.