Study On Solid Phase Synthesis Of An Antimicrobial Decapeptide And Its Stability

Antimicrobial peptides are a kind of small molecules have antibacterial activities which were generated by induction in vivo. These peptides are potent, broad spectrum antibacterial. Unlike traditional antibiotics, antimicrobial peptides can also act as immunomodulatory agents to improve immunity of organism that have bright prospects in application.In this research, the synthesized peptide NS was screened from phage display peptide library, which has antimicrobacterial activity and can improve host’s immunity. The focus of this research is to find a viable way to synthesize peptide NS through solid-phase peptide synthesis method and optimize its procession in order to provide a theoretical basis for large-scale production.In this study, we selected the Fmoc protection strategy, Rink amide-MBHA resin as the carrier, the combine of TBTU-HOBt-DIEA as coupling reagents,25%piperidine-DMF solution as deprotection reagent to synthesize peptide. After each round of coupling we used the ninhydrin method to examine the condensation degree and determined the peptide coupling rate by measuring the absorbance of the Fmoc group. The intramolecular disulfide bond of peptide NS was bridged by I2oxidation and examined by reacting with DTNB. After coupling the decapeptide was cut off from resins by using mixed reagent TFA/H2O/TIS. RP-HPLC was applied to purify crude peptide, which was then characterized by MALDI-TOF MS. Some of the steps were studied. Based on this, we preliminarily studied the stability of peptide by comparing the peptide NS samples’zone of inhibition in different condition of temperatures and pH, storage time.The results showed that the yield of synthesized crude peptide was78.73%and the yield of peptide after purified was59.51%. The minimum inhibitory concentration of NS in E. coli was3000μg/ml. Peptide NS showed good stability under the condition between40-60℃, pH6-8and sealed storage by comparing the size of the samples’zone of inhibition.The main conclusion drawn from this research was that we had established a complete procession of synthesizing and purifying peptide NS, and studied its stability primarily. It provides a foundation and reference for large-scale synthesis of such peptides.