抗菌肽Met-Ala-Lys对铜绿假单胞菌细胞膜的作用机制

Mechanism of Antibacterial Peptide Met-Ala-Lys Affecting on the Cytomembrane of Pseudomonas aeruginosa

以抗菌肽Met-Ala-Lys(MAK)和铜绿假单胞菌为研究对象,采用NPN荧光探针法,圆二色谱法以及原子吸收光谱测定测定铜绿假单胞菌细胞膜结构的变化,探讨MAK对目标菌生长的影响作用机制。结果表明:随着MAK对铜绿假单胞菌作用时间的增加,MAK的二级结构尤其是无规则卷曲结构发生变化明显,细胞内膜(吸附速率从54.03%降至27.33%)和外膜(荧光强度在前30min持续增强,30min后基本稳定在45左右)受到影响,通透性明显增强,导致钾离子(从处理10min时迅速增加)和蛋白质泄漏量(从4.65μg/mL到10.25μg/mL)以及细胞膜的疏水性随之增加,细胞表面膜电位发生变化。表明MAK能改变铜绿假单胞菌的表面特性,抑制其生长,进而起到抗菌作用。本研究为抗菌肽MAK的抗菌机理制研究奠定一定的理论基础。

The present study investigated the antibacterial effected of the peptide Met-Ala-Lys (MAK) on the structure of Pseudomonas aeruginosa based on the NPN fluorescence method, the circular dichroism spectroscopy analysis, and the level of potassium ions and protein were employed respectively to characterize the extracellular membrane permeability, the variation of secondary structure, and the cell surface hydrophobicity and its endometrial permeability induced by the MAK. The results showed that with the increase of time, the secondary-structure, specially the Random coil, of MAK changed, resulting in the leakage of potassium (getting rapidly from the first 10 min) and protein were significantly high (from 4.65 μg/mL to 10.25 μg/mL), indicating that the inner (from 54.03% to 27.33%) and outer (increase rapidly in the first 30 min and basically stable at around 45 after 30 min ) membrane permeability were changed, thus, MAK can change the surface characteristics of Pseudomonas aeruginosa and contribute to the inhibition of bacterial growth. These results may provide some information for further study of antibacterial peptide, especially in the aspect of the mechanism of antibacterial peptide Met-Ala-Lys.