抗菌肽SAMP1及其类似肽的构效关系

以人工合成抗菌肽1(Synthetic antimicrobial peptide 1, SAMP1)为研究模板, 采用氨基酸序列重排、 不同的带正电荷氨基酸残基和疏水性氨基酸残基取代等方法, 设计合成了8条SAMP1类似肽. 利用生物信息学软件预测了SAMP1及其类似肽的理化性质; 采用圆二色光谱(CD)技术测定其在不同环境下二级结构的变化; 采用噻唑蓝(MTT)法测定其抗菌活性; 通过红细胞溶血实验评估了这些多肽的溶血性. 结果表明, 大部分类似肽具有较低的溶血毒性和较高的广谱抗菌活性. CD光谱分析结果显示, 大部分类似肽二级结构以α螺旋和无规则卷曲为主, 在体积分数为50%的2,2,2-三氟乙醇(TFE)溶液中, α螺旋结构比例增加. 与母肽SAMP1相比, 经序列重排后得到的SAMP1-A1, SAMP1-A2和SAMP1-A3的抗菌活性变化不大, 但序列中正电荷氨基酸残基均匀分布的类似肽SAMP1-A2的溶血毒性增加. 用精氨酸(Arg)取代SAMP1序列中的赖氨酸(Lys)得到的类似肽SAMP1-A4的抗菌活性增强, 同时溶血毒性降低. 用疏水性较强的异亮氨酸(Ile)和缬氨酸(Val)取代SAMP1中的疏水性氨基酸残基, 得到的类似肽SAMP1-A5和SAMP1-A7的抗菌活性急剧降低; 用疏水性较弱的色氨酸(Trp)取代SAMP1中的疏水性氨基酸残基, 得到的类似肽SAMP1-A8的抗菌活性增强, 同时溶血毒性提高.

Structure-activity Relationship of Antimicrobial Peptide SAMP1 and Its Analog Peptides†

The synthetic antimicrobial peptide 1(SAMP1) was used as the research template, eight SAMP1 analog peptides were designed and synthesized by amino acid sequence rearrangement, different positive charged amino acids replacement and hydrophobic amino acid substitutions. Bioinformatics software was used to predict the physicochemical properties of SAMP1 and its analog peptides. Secondary structures were determined by circular dichroism(CD) technique. Antimicrobial activity was determined by 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazoliumbromide(MTT) assay. Hemolytic properties of peptides were evaluated by erythrocyte hemolysis assay. The results showed that most of the analogues of SAMP1 had low hemolytic toxicity, and high broad-spectrum antimicrobial activity. The results of CD showed that their secondary structures were mainly α-helix and random coil, the proportion of α-helix increased in the 50% volume fraction of 2,2,2-trifluoroethanol(TFE) solution. Compared with mother peptide SAMP1, the antimicrobial activities of the analog peptides SAMP1-A1, SAMP1-A2 and SAMP1-A3, which were obtained after sequence rearrangement, did not change so much. While the hemolytic toxicity of SAMP1-A2, in which uniform distribution of positive charged amino acids in the sequence, increased. The antimicrobial activity of the peptide SAMP1-A4, which was obtained by substituting arginine(Arg) for lysine(Lys) in the SAMP1 sequence, improved with less hemolytic toxicity. The antimicrobial activity of the peptides SAMP1-A5 and SAMP1-A7, obtained by replacing the hydrophobic amino acids in SAMP1 with strong hydrophobic amino acids isoleucine(Ile) and valine(Val), drastically reduced. Both of the antibacterial activity and the hemolytic toxicity of the peptide SAMP1-A8 increased, in which less strong hydrophobic amino acid tryptophan(Trp) replaced the hydrophobic amino acids in SAMP1.