关键词: KW-WK肽, 抑菌活性, 溶血活性, 细胞毒性, 稳定性

Abstract: This study designed a new anti-microbial peptide KWRRWQWRRWK-NH2 (KW-WK) with the fragment of bovine lactoferricin LFcinB18-28 as parent peptide. Apart from retaining the high charge and strong hydrophobicity of the parent peptide, arginine (R) and tryptophan (W) replacement was introduced to design this anti-microbial peptide based on the concept of symmetrical structure. The secondary structure, antibacterial activity, hemolysis activity, cell toxicity and stability of KW-WK were determined by circular dichroism spectroscopy, broth microdilution and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) method. The results showed that KW-WK existed in a random coil structure in aqueous solution. However, it was α-helical in the simulated environment of cell membrane. The minimal inhibitory concentration (MIC) of KW-WK ranged from 4 to 128 μmol/L, suggesting that its bacteriostatic activity was strong. The hemolysis rate was less than 5% when the concentration of KW-WK was 256 μmol/L. This result showed that its hemolysis activity was low. The therapeutic index of KW-WK was 9.14, and its cytotoxicity was relatively low. Thus, its cell selectivity was relatively high. In addition, after heat treatment 100 ℃ for 1 h, KW-WK still possessed rather high antibacterial activity. The enzymatic stability of KW-WK was greatly improved as compared to LFcinB18-28. Therefore, the new anti-microbial peptide KW-WK has shown a great application potential in the fields of food, medicine, livestock etc.

Key words: KW-WK peptide, antibacterial activity, hemolytic activity, cytotoxicity, stability