Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, North Carolina 28403, United States.
Biochemistry. 2011 Feb 8;50(5):654-62. doi: 10.1021/bi1013358. Epub 2011 Jan 11.
We report a first test of the hypothesis that the mechanism of antimicrobial, cytolytic, and amphipathic cell-penetrating peptides in model membranes is determined by the thermodynamics of insertion of the peptide into the lipid bilayer from the surface-associated state. Three peptides were designed with minimal mutations relative to the sequence of TP10W, the Y3W variant of transportan 10, which is a helical, amphipathic cell-penetrating peptide previously studied. Binding to 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) membranes and release of dye from those vesicles were assessed by stopped-flow fluorescence, and the secondary structure of the peptides on the membrane was determined by circular dichroism. The Gibbs energy of binding determined experimentally was in excellent agreement with that calculated using the Wimley-White interfacial hydrophobicity scale, taking into account the helical content of the membrane-associated peptide. Release of dye from POPC vesicles remained graded, as predicted by the hypothesis. More significantly, as the Gibbs energy of insertion into the bilayer became more unfavorable, which was estimated using the Wimley-White octanol hydrophobicity scale, dye release became slower, in quantitative agreement with the prediction.
我们首次测试了一个假设，即模型膜中抗菌、溶细胞和两亲性细胞穿透肽的作用机制取决于肽从表面相关状态插入脂质双层的热力学。相对于转运蛋白 10（TP10）的序列，设计了三个最小突变的肽，转运蛋白 10 是一种先前研究过的螺旋、两亲性细胞穿透肽的 Y3W 变体。通过停流荧光评估与 1-棕榈酰基-2-油酰基磷脂酰胆碱（POPC）膜的结合以及从那些囊泡中释放染料，通过圆二色性确定肽在膜上的二级结构。实验确定的结合吉布斯自由能与考虑到膜相关肽的螺旋含量后使用 Wimley-White 界面疏水性标度计算的吉布斯自由能非常吻合。根据该假说，从 POPC 囊泡中释放染料仍然呈梯度变化。更重要的是，当插入双层的吉布斯自由能变得更不利时，这是使用 Wimley-White 辛醇疏水性标度估计的，染料释放变得更慢，与预测定量一致。
