新型抗菌肽的设计、活性研究及与磷脂相互作用的计算模拟

设计合成了多个具有2个活性序列的线性和环状多肽及具有单个活性序列的短链多肽, 研究了它们的杀菌活性, 发现其杀菌活性顺序为长链肽>环状肽>短链肽, 特别是线性的Linear-KT和Linear-KS对多种革兰氏阴性菌和阳性菌均具有较高的杀菌活性. 采用MTT法考察了Linear-KT和Linear-KS对正常细胞的毒性, 其中Linear-KS表现出较低的细胞毒性, 优于阳性对照多粘菌素B. 利用计算模拟的方法计算了多肽与细菌细胞膜中磷脂酰甘油(DMPG)的相互作用. 结果表明, 多肽和DMPG的结合能也表现出长链肽>环状肽>短链肽的规律, 特别是Linear-KT和Linear-KS具有较高的结合能. 长链肽含有2个活性序列, 可提供多个荷正电的氨基酸与荷负电的磷脂结合, 结合能较大, 杀菌活性较强. 同时, 柔性的结构及Linear-KT和Linear-KS中丝氨酸和苏氨酸的β碳上的羟基可与磷脂上的羰基形成多个氢键, 进一步增大了结合能. 计算模拟的方法为抗菌肽的杀菌活性从理论上提供了一定的依据.

Design and Bioactivity of Novel Antimicrobial Peptides and Its Computer Simulation with Phospholipid

Linear and cyclic peptides with two bioactive sequences and peptides with single bioactive sequence were designed and synthesized, followed by the investigation of their antibacterial activities. The results showed that the antibacterial activity sequence was linear peptides>cyclic peptides>short peptides. Especially linear peptides Linear-KT and Linear-KS showed high antibacterial activity against Gram-negative and Gram-positive bacteria. The toxicities of Linear-KT and Linear-KS against normal cell were also investigated by MTT method. Linear-KS showed low cell toxicity, which is better than the positive control Polymyxin B, implying a potential further investigation and application. The interaction between peptides and an important component of bacterial cell membrane phosphatidylglycerol(DMPG) was investigated by computer simulation. The results indicated that the binding energy between peptides and DMPG shows linear peptides>cyclic peptides>short peptides, especially Linear-KT and Linear-KS with higher binding energy. Linear peptides with two bioactive sequence provide more positively charged amino acids, which bind to negatively charged phospholipid, leading to higher binding energy and stronger antibacterial activity. Simultaneously flexible conformation and the hydroxyl group on β-C of serine and threonine in Linear-KT and Linear-KS could form more hydrogen bonds with carbonyl group in phospholipid, which further increases the binding energy. The computer simulation method provides theoretical evidence for antibacterial activity of antimicrobial peptides to some extent.