The Effect Of D-amino Acid Substitution Modification And Fine-tuning Of Lysine Side Chain On The Bioactivity And Stability Of Antimicrobial Peptide Polybia-CP

Due to the extensive use and abuse of antibiotics in medicine,agriculture and food industry,the frequency of emergence of resistant microbes increased dramatically,which made traditional antibiotics with limited use in clinic.However,in recent decades,there are few novel antibiotics used in clinic,drug-resistant bacteria infections become a major threat to health and human life.Therefore,there is an urgent need to develop novel antimicrobial agents.Antimicrobial peptides(AMPs)have unique mechanism of action,which is not affected by the traditional resistance mechanism,are believed to be one kind of ideal leading compounds.However,natural AMPs can be easily degraded by endogenous protease(such as trypsin),which greatly limits its therapeutic use in vivo.Cationic antimicrobial peptide polybia-CP was isolated from the venom of the wasp polybia paulist,its primary amino acid sequence is ILGTILGLLKSL-NH2(1239.73 Da).It has broad spectrum antimicrobial activity,antifungal activity and antitumor activity,however,it can be easily degraded by protease like other natural antimicrobial peptides.In the present study,D-amino acid substitution and fine-tuning of lysine side chain strategy were employed to enhance the stability of polybia-CP.Then,a series of derivatives of polybia-CP were synthesized to investigate the effects of these modification on the antimicrobial activity,antifungal activity,secondary structure,cell toxicity,mechanism of action and the stability against trypsin were investigated.Our results showed that most of the derivatives maintained the same or comarable antimicrobial activity with their parent peptide,exhibited improved trypsin resistance and exerted their antimicrobial activity through the similar action mechanism with polybia-CP.Although Dap-CP,His-CP and D-Lys-CP showed a slight weaker antimicrobial activity than polybia-CP,their hemolytic activity decreased greatly.Especially,the hemolysis rate of D-Lys-CP was approximate 0 at the concentration of 64 ?M.In addition,we found that these peptides also can effectively inhibit the formation of biofilms.These results suggested that D-amino acid substitution and fine-tuning of lysine side chain strategy may offer a novel strategy to improve the property of AMPs,and polybia-CP also can be a leading compound for the research of novel antimicrobial agents.