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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >Poly-l-lysines and poly-l-arginines induce leakage of negatively charged phospholipid vesicles and translocate through the lipid bilayer upon electrostatic binding to the membrane.
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Poly-l-lysines and poly-l-arginines induce leakage of negatively charged phospholipid vesicles and translocate through the lipid bilayer upon electrostatic binding to the membrane.

机译：聚-1-赖氨酸和聚-1-精氨酸诱导带负电荷的磷脂囊泡泄漏，并在静电结合到膜上时通过脂质双层移位。

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摘要

Poly-l-lysines (PLL) and poly-l-arginines (PLA) of different polymer chain lengths interact strongly with negatively charged phospholipid vesicles mainly due to their different electrical charges. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) and their mixtures (1/1 mol/mol) with the respective phosphatidylcholines of equivalent chain length were chosen as model membrane systems that form at room temperature either the fluid L(alpha) or the gel phase L(beta) lipid bilayer membranes, respectively. Leakage experiments revealed that the fluid POPG membranes are more perturbed compared to the gel phase DPPG membranes upon peptide binding. Furthermore, it was found that pure PG membranes are more prone to release the vesicle contents as a result of pore formation than the lipid mixtures POPG/POPC and DPPG/DPPC. For the longer polymers (>or=44 amino acids) maximal dye-release was observed when the molar ratio of the concentrations of amino acid residues to charged lipid molecules reached a value of R(P)=0.5, i.e. when the outer membrane layer was theoretically entirely covered by the polymer. At ratios lower or higher than 0.5 leakage dropped significantly. Furthermore, PLL and PLA insertions and/or translocations through lipid membranes were analyzed by using FITC-labeled polymers by monitoring their fluorescence intensity upon membrane binding. Short PLL molecules and PLA molecules of all lengths seemed to translocate through both fluid and gel phase lipid bilayers. Comparison of the PLL and PLA fluorescence assay results showed that PLA interacts stronger with phospholipid membranes compared to PLL. Isothermal titration calorimetry (ITC) measurements were performed to give further insight into these mechanisms and to support the findings obtained by fluorescence assays. Cryo-transmission electron microscopy (cryo-TEM) was used to visualize changes in the vesicles' morphology after addition of the polypeptides.
机译：聚合物链长不同的聚-1-赖氨酸（PLL）和聚-1-精氨酸（PLA）主要由于带电荷的不同而与带负电荷的磷脂囊泡强烈相互作用。 1-棕榈酰基-2-油酰基-sn-甘油-3-磷酸甘油（POPG），1,2-二棕榈酰基-sn-甘油-3-磷酸甘油（DPPG）及其混合物（1/1 mol / mol）与各自的磷脂酰胆碱选择当量链长相等的链作为模型膜系统，其在室温下分别形成液体Lα或凝胶相Lβ脂质双层膜。泄漏实验表明，与肽相结合后的凝胶相DPPG膜相比，液体POPG膜更易受到干扰。此外，已经发现，与脂质混合物POPG / POPC和DPPG / DPPC相比，纯PG膜由于形成孔而更易于释放囊泡内容物。对于更长的聚合物（>或= 44个氨基酸），当氨基酸残基浓度与带电脂质分子的摩尔比达到R（P）= 0.5时，即在外膜层时，观察到最大的染料释放理论上完全被聚合物覆盖。比率低于或高于0.5时，泄漏量显着下降。此外，通过使用FITC标记的聚合物通过监测膜结合后的荧光强度，分析了通过脂质膜的PLL和PLA插入和/或易位。各种长度的短PLL分子和PLA分子似乎都可以通过流体和凝胶相脂质双层转移。 PLL和PLA荧光测定结果的比较表明，与PLL相比，PLA与磷脂膜的相互作用更强。进行了等温滴定热法（ITC）测量，以进一步了解这些机理并支持通过荧光测定获得的发现。添加多肽后，使用低温透射电子显微镜（cryo-TEM）可视化囊泡的形态变化。

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