Study On The Structure And Antibacterial Mechanism Of Artificial Peptides

Due to the safety and efficacy, antimicrobial peptides have good prospects in food additives application. The main biological activity of antimicrobial peptides is antibacterial. In order to reveal the principle of antimicrobial peptides, and to explore the high activity of antimicrobial peptides, the structure and properties of the modified polypeptide and its modified peptides were studied. In this paper, two kinds of amino acid peptides were designed. The structure and morphology of the two peptides were characterized, and the performance of the antibacterial peptide was evaluated by measuring the rupture of the lipid bilayer. Finally, the antibacterial activity and mechanism were revealed. We use the Malvin laser particle size analyzer and fluorescence spectrophotometer to detect the interaction of polypeptide and liposome.The secondary structure, morphology and aggregation of the dynamic process of polypeptide aggregates were studied by circular dichroism(CD), Atomic Force Microscope(AFM), Quartz Crystal Microbalance(QCM). The antimicrobial properties of the peptides were characterized. The main results were as follows:(1) The introduction of lysine can slow down the rate of self-assembly and improve the ability of membrane rupture. The secondary structure, morphology and aggregation of polypeptide aggregates were characterized by Atomic Force Microscope, Quartz Crystal Microbalance and circular dichroism and other detection means. The results show that the self-assembly speed of KKKAβ33-42 is less than Aβ33-42. The secondary structure of the polypeptide has been changed after the action with liposome by CD. It was found that the effect of KKKAβ33-42 on the membrane of the liposome was enhanced by the leakage of liposome after introducing a positive charge of lysine.(2) Two kinds of peptides KKK(FAFAFAFA)KKK and KKKKKKFAFAFAFA were successfully designed and they were characterized by CD, QCM and AFM.Results show that two kinds of peptides were self-assembled into fibers with incubation and the effect of liposomes on the conformation of K3(FA)4K3 aggregates.Experimental results of the leakage of liposome fluorescent substance show the effectof polypeptide K3(FA)4K3 on the destruction of liposome membrane was stronger. It shows that lysine sequence can change the membrane breaking ability of the polypeptide.(3) The antibacterial properties and antibacterial mechanism of polypeptide K3(FA)4K3 and K6(FA)4 were validated. Polypeptide showed good antibacterial property, and its MIC and MBC of E.coli were 62.5ppm. The antibacterial mechanism of the polypeptide K3(FA)4K3 on the E.coli is the destruction of the bacterial cell membrane, which leads to the loss of ATP, DNA and other substances in the cell.