The objective of the study is to analyze the biological characteristics and stability of the linear derivative Bac2a from bactenecin, compared with the control peptide melittin. The secondary structure, antibacterial activity, hemolytic activity, cell toxicity and stability of the Bac2a were determined by circular dichroism spectroscopy, broth micro-dilution method and MTT assay. The results showed that Bac2a was a nonregular curl in aqueous solution, however, it was an α-helix structure in the hydrophobic environment. The minimal inhibitory concentration (MIC) of Bac2a ranged from 2 to 32 μmol/L, so the bacteriostatic activity of Bac2a was strong. The hemolytic rate was only 14.81% when the concentration of Bac2a was 64 μmol/L, which showed that the hemolytic rate of Bac2a was low. The therapy index of Bac2a was 3.26, and the cytotoxicity was relatively low, thus the cell selectivity was relatively high. In addition, with the heating treatment of 100℃ for 1 h, Bac2a still possessed rather a high antibacterial activity and showed a good heating stability. In a word, Bac2a has good application prospects in food, medicine and other fields, and is expected as a substitute for traditional antibiotics.
本研究以牛中性粒细胞牛溶菌肽的线性衍生物 Bac2a 为研究对象，以蜂毒素为对照肽，探讨 Bac2a 的生物特性及其稳定性。采用圆二色谱法、微量稀释法、噻唑蓝（MTT）法等方法测定了 Bac2a 的二级结构、抑菌活性、溶血活性、细胞毒性及其稳定性。研究结果表明：Bac2a 在水溶液中呈无规则卷曲状，在疏水环境中则呈 α-螺旋结构；Bac2a 的抑菌作用较强，最小抑菌浓度（MIC）为 2～32 μmol/L；当肽浓度为 64 μmol/L 时，其溶血率较低，仅为 14.81%；细胞毒性小，治疗指数为 3.26，细胞选择性较强；100℃ 处理 1 h 后，Bac2a 依然保持较强的抑菌活性，热稳定性好。因此，Bac2a 在食品、医药和其它领域都具有良好的应用前景，有望成为抗生素替代品。.
Keywords: Bac2a peptides; antibacterial activity; cytotoxicity; hemolytic activity; stability.