Esbjörner Elin K, Lincoln Per, Nordén Bengt
Department of Chemical and Biological Engineering, Physical Chemistry, Chalmers University of Technology, Kemivägen 10, SE-412 96 Gothenburg, Sweden.
Biochim Biophys Acta. 2007 Jun;1768(6):1550-8. doi: 10.1016/j.bbamem.2007.03.004. Epub 2007 Mar 19.
Arginine-rich cell-penetrating peptides (CPPs) can enter cells non-endocytotically, despite that transport of charge across a membrane should be formally associated with an extremely high Born energy barrier. We studied partitioning of several derivatives of the CPP penetratin in a water-octanol two-phase system in presence of natural phospholipids to explore if solvation by ion-pairing to hydrophobic counter-ions may serve as a mechanism for cell internalisation. We demonstrate that anionic lipids can aid peptide partitioning into octanol. Particularly efficient partitioning into octanol is observed with an arginine-rich penetratin compared to a lysine-rich derivative. Substituting tryptophans for phenylalanines results in poor partitioning into octanol, due to decreased overall peptide hydrophobicity. Partitioning into octanol is dependent of phospholipid type and the peptides induced structural changes in the lipid assemblies found in octanol. Attachment of carboxyfluorescein as a model cargo was found to enhance peptide partitioning into octanol. We discuss our results with respect to theoretical electrostatic energies, empirical hydrophobicity scales and in terms of implications for CPP uptake mechanisms. An important improvement of the theoretical transfer energies is obtained when, instead of singular ions, the insertion of ion-paired dipolar species is considered.
富含精氨酸的细胞穿透肽（CPPs）可以通过非内吞方式进入细胞，尽管电荷跨膜运输理论上应与极高的玻恩能垒相关。我们研究了在天然磷脂存在的情况下，CPP穿膜肽的几种衍生物在水 - 辛醇两相系统中的分配情况，以探索与疏水性抗衡离子形成离子对的溶剂化作用是否可作为细胞内化的一种机制。我们证明阴离子脂质可以帮助肽分配到辛醇中。与富含赖氨酸的衍生物相比，富含精氨酸的穿膜肽在辛醇中的分配效率特别高。用色氨酸取代苯丙氨酸会导致在辛醇中的分配不佳，这是由于肽的整体疏水性降低所致。在辛醇中的分配取决于磷脂类型以及肽在辛醇中脂质聚集体中诱导的结构变化。发现连接作为模型货物的羧基荧光素可增强肽在辛醇中的分配。我们从理论静电能、经验疏水性标度以及对CPP摄取机制的影响等方面讨论了我们的结果。当考虑插入离子对偶极物种而非单个离子时，理论转移能有了重要改进。
