Structural Changes and Antibacterial Activity of Epsilon-poly-L-lysine in Response to pH and Phase Transition and Their Mechanisms
Structural Changes and Antibacterial Activity of Epsilon-poly-L-lysine in Response to pH and Phase Transition and Their Mechanisms
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DOI：
10.1021/acs.jafc.9b07524
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发表时间：
2020-01-29
影响因子：
6.1
通讯作者：
Zhao, Qing-Sheng
中科院分区：
文献类型：
--
作者：
Liu, Jia-Ning;Chang, Sen-Lin;Zhao, Qing-Sheng
epsilon-Poly-L-lysine （epsilon-PL）由25-35个赖氨酸残基组成，这些残基由α -羧基和epsilon-氨基脱水缩合形成异肽键连接，具有良好的抗菌活性和广谱抑制范围。然而，epsilon-PL在水溶液中的结构和抑菌机理尚无明确的结论。本文采用Amberlite IRC-50离子交换树脂制备了高纯度的epsilon-PL。采用膜过滤和动态光散射技术研究了epsilon-PL在水溶液中的聚集随pH值的变化。采用圆二色性（CD）和抑菌带研究了epsilon-PL和氨基甲酰化epsilon-PL在不同水环境中的构象变化和抑菌活性。利用傅里叶变换红外光谱分析了喷雾干燥过程中的结构变化。结果表明，侧链氨基电荷对epsilon-PL的构象和聚集起决定性作用。epsilon-PL在从酸性液体到固体的喷雾干燥过程中表现出β -片的性质。阳离子对epsilon-PL的抑菌活性有增强作用，但不起关键作用。相反，epsilon-PL的主链可能决定了epsilon-PL的抗菌机制。
epsilon-Poly-L-lysine (epsilon-PL) consists of 25-35 lysine residues which are linked by an isopeptide bond formed by dehydration condensation of alpha-carboxyl and epsilon-amino groups and has good antibacterial activity and broad-spectrum inhibition range. However, there is no clear conclusion about the structure and antibacterial mechanism of epsilon-PL in aqueous solution. Herein, a high purity of epsilon-PL was prepared using Amberlite IRC-50 ion-exchange resin. Membrane filtration and dynamic light scattering were used to study the variations of epsilon-PL aggregation in aqueous solution with pH value. The conformational changes and antibacterial activities of epsilon-PL and carbamoylated epsilon-PL in different water environments were studied with circular dichroism (CD) and inhibition zone. The structural changes during the spray-drying process were determined by Fourier transform infrared spectroscopy. The results indicated that the side chain amino charge played a decisive role in the epsilon-PL conformation and aggregation. epsilon-PL exhibited the properties of a beta-sheet during spray drying from acidic liquids to solids. The cation enhanced the antibacterial activity of epsilon-PL but did not play a key role. Instead, the backbone of epsilon-PL might determine the mechanism of epsilon-PL antibacterial.