Department of Chemistry, Waterloo Institute for Nanotechnology , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada.
Langmuir. 2018 Jun 26;34(25):7545-7553. doi: 10.1021/acs.langmuir.8b00864. Epub 2018 Jun 12.
Natural lipid headgroups contain a few types of metal ligands, such as phosphate, amine, and serine, which interact with metal ions differently. Herein, we studied the binding between Cu and liposomes with four types of headgroups: phosphocholine (PC), phosphoglycerol (PG), phosphoserine (PS), and cholinephosphate (CP). Using fluorescently headgroup-labeled liposomes, Cu strongly quenched the CP and PS liposomes, whereas quenching of PC and PG was weaker. Dynamic light scattering indicated that all of the four liposomes aggregated at high Cu concentrations, and ethylenediaminetetraacetic acid (EDTA) only restored the original size of the PC liposome, implying fusion of the other three types of liposomes. The leakage tests revealed that the integrity of PC liposomes was not affected by Cu, but the other three liposomes leaked. Under TEM, all of the liposomes show a positive-stain feature in the presence of Cu and Cu-stained individual liposomes with a short incubation time (<1 min). The oxidative catalytic property of Cu was also tested, and a tight binding by the PS liposome inhibited the activity of Cu. Finally, a model of interaction for each liposome was proposed, and each one has a different metal-binding and interaction mechanism.
天然脂质头基包含几种金属配体，如磷酸、胺和丝氨酸，它们与金属离子的相互作用方式不同。本文研究了带四种头基（磷酸胆碱（PC）、磷酸甘油（PG）、磷酸丝氨酸（PS）和磷酸胆碱（CP））的脂质体与 Cu 的结合。使用荧光标记的脂质体，Cu 强烈猝灭 CP 和 PS 脂质体，而对 PC 和 PG 的猝灭作用较弱。动态光散射表明，四种脂质体在高 Cu 浓度下均发生聚集，而乙二胺四乙酸（EDTA）仅恢复了 PC 脂质体的原始大小，这意味着其他三种脂质体发生了融合。泄漏实验表明，Cu 对 PC 脂质体的完整性没有影响，但其他三种脂质体发生了泄漏。在 TEM 下，所有的脂质体在 Cu 存在下都呈现正染色特征，且 Cu 短时间孵育（<1 分钟）后可染色单个脂质体。还测试了 Cu 的氧化催化性质，PS 脂质体的紧密结合抑制了 Cu 的活性。最后，提出了每种脂质体的相互作用模型，并且每种脂质体都具有不同的金属结合和相互作用机制。
