Prokaryotic Expression, Purification Of Antimicrobial Peptide SK84and The Preliminary Study On Its Activity And Structure

Antimicrobial peptides appear to be ubiquitous and multipotent components of theinnate immune defense system used by both prokaryotic and eukaryotic organisms. Theamphiphilic α-helix structure is important for their antimicrobial activity. Compared withtraditional antibiotics, antimicrobial peptides have many advantages including wideantibacterial spectrum and low drug resistance, therefor, they might be developed intonew drugs to defend microbial infection.SK84is a novel antibacterial peptide identified from the maggot by Dr. Lu Jie in2006. SK84can penetrate the cell membrane, resulting in the death of gram-positivebacteria. Additionally, SK84inhibits the proliferation of HepG2, MCF-7andMDA-MB-231.It’s difficult to separate and purify SK84from natural materials. In our study, SK84was expressed and purified in prokaryotic system. We also identified the secondarystructure and detected the antimircrobial activity. The main results as fellows:1) The recombinant plasmid of pET-32a(+)-SK84-His6was constructed andexpressed in E.coli.2) Optimum inducing time, temperature, IPTG concentration and initial OD valuefor SK84expression were found, which were4h,37℃,1.0mM and1.0,respectively3) The results showed that the expressed SK84inhibited the growth of Bacillusthuringiensis and Bacillus subtilis, and promoted the apoptosis of HepG2cells.4) The analysis of the secondary structure of SK84revealed that there was anamphiphilic α-helix structure in SK84, which played a crucial role in itsantimicrobial activity.In conclusion, we obtained highly purified and antimicrobial SK84protein by prokaryotic expression, which provided a foundation for futher research on SK84.Moreover, the results of structure study indicated that SK84might exert antimicrobialeffect by forming an amphiphilic α-helix structure.