阳离子肽ε-聚赖氨酸与负电荷多糖复合物的形成动力学、解离效应及作用机制

Complexation Kinetics, Dissociation, and Interaction Mechanism of Cationic Peptide ε-Poly-L-Lysine Complexed with Negatively Charged Polysaccharides

摘要:

聚赖氨酸(ε-poly-L-lysine, ε-PL)是一种高正电荷密度的抗菌肽,目前主要作为天然防腐剂用于食品工业,但ε-PL抑菌效果易受食品体系中负电荷多糖等成分的影响。研究了负电荷多糖[negatively charged polysaccharides,PS(-)]海藻酸钠(NaAlg)、羧甲基纤维素钠(CMC-Na)及κ-卡拉胶(κ-carrageenan, Carra)与ε-PL形成复合物的动力学机制,以及温度、pH值、离子强度、食品成分(蔗糖)对复合物的解离效应,利用红外光谱分析PS(-)与 ε-PL的作用机制。结果表明,NaAlg或CMC-Na与ε-PL的质量比对复合物形成有直接影响,质量比1∶1时无相互作用,8∶1以上时快速形成复合物；Carra与ε-PL形成复合物的速度低于NaAlg和CMC-Na。温度高于40℃对ε-PL/NaAlg和ε-PL/CMC-Na有解离效应,但对ε-PL/Carra无作用。碱性条件下,3种ε-PL/PS(-)复合物均发生解离。NaCl对ε-PL/NaAlg和ε-PL/CMC-Na有解离作用,完全解离的NaCl质量浓度分别为30、25mg/mL,但对ε-PL/Carra不起作用。蔗糖质量浓度为50mg/mL时,ε-PL/NaAlg完全解离；90mg/mL时,ε-PL/CMC-Na完全解离；但蔗糖对ε-PL/Carra无解离作用。红外光谱显示,ε-PL与NaAlg、CMC-Na和Carra主要存在静电和氢键相互作用。研究旨在为ε-PL在食品领域的应用与功能调控提供一定的科学依据。

Abstract:

Poly-L-lysine (ε-PL) is a polycationic antimicrobial peptide with a high positive charge density, widely used as a natural preservative in the food industry. However, ε-PL is susceptible to the influence of negatively charged polysaccharides and other components in food matrices. In order to investigate the kinetics of complexation kinetics between ε-PL and negatively charged polysaccharides , including sodium alginate (NaAlg), sodium carboxymethyl cellulose (CMC-Na), and κ-carrageenan (Carra), and explore the dissociation effects of temperature, pH, ionic strength, and food ingredients (sucrose) on the ε-PL/PS(-) complexes, the interaction mechanism between PS(-) and ε-PL was analyzed with infrared spectra. The results showed that the mass ratio of NaAlg or CMC-Na to ε-PL had a significant effect on the formation of complexes. There was no interaction at the mass ratio of NaAlg or CMC-Na/ε-PL at 1∶1, and the rapid formation of complexes was observed at mass ratio of 8∶1 or above. While for Carra, the complexation process was slower than that of NaAlg and CMC-Na with ε-PL. Temperatures above 40℃caused the dissociation of the ε-PL/NaAlg and ε-PL/CMC-Na complexes, but had no effect on the complexation of ε-PL/Carra. All three ε-PL/PS(-) complexes were dissociated under alkaline conditions. The ε-PL/NaAlg and ε-PL/CMC-Na complexes were dissociated by NaCl, and the complete dissociation was achieved at the NaCl concentration of 30mg/mL and 25mg/mL, respectively. There was no dissociation effect of NaCl on the ε-PL/Carra complexes. Sucrose at 50mg/mL led to the complete dissociation of ε-PL/NaAlg complexes, and 90mg/mL sucrose induced the complete dissociation of ε-PL/CMC-Na complexes, while sucrose was ineffective for the ε-PL/Carra complexes. The infrared spectra indicated that the electrostatic forces and hydrogen bonds were responsible for the interactions between NaAlg, CMC-Na and Carra with ε-PL. This study aimed to provide a scientific guideline for the practical application and functional regulation of ε-PL in the food industry.