Structural Changes and Antibacterial Activity of Epsilon-poly- l -lysine in Response to pH and Phase Transition and Their Mechanisms

作者：Jianing Liu, Senlin Chang, Peng‐Wei Xu, Minghui Tan, Bing Zhao, Xiaodong Wang, Qingsheng Zhao · 发表于：Journal of Agricultural and Food Chemistry · 年份：2020 · DOI：10.1021/acs.jafc.9b07524 · 被引用次数：66 · 研究领域：Biopolymer Synthesis and Applications、Advanced biosensing and bioanalysis techniques、Antimicrobial agents and applications

ε-Poly-l-lysine (ε-PL) consists of 25-35 lysine residues which are linked by an isopeptide bond formed by dehydration condensation of α-carboxyl and ε-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 ε-PL in aqueous solution. Herein, a high purity of ε-PL was prepared using Amberlite IRC-50 ion-exchange resin. Membrane filtration and dynamic light scattering were used to study the variations of ε-PL aggregation in aqueous solution with pH value. The conformational changes and antibacterial activities of ε-PL and carbamoylated ε-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 ε-PL conformation and aggregation. ε-PL exhibited the properties of a β-sheet during spray drying from acidic liquids to solids. The cation enhanced the antibacterial activity of ε-PL but did not play a key role. Instead, the backbone of ε-PL might determine the mechanism of ε-PL antibacterial.