Almeida Paulo F, Ladokhin Alexey S, White Stephen H
Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
Biochim Biophys Acta. 2012 Feb;1818(2):178-82. doi: 10.1016/j.bbamem.2011.07.019. Epub 2011 Jul 22.
The free energy cost ΔG of partitioning many unfolded peptides into membrane interfaces is unfavorable due to the cost of partitioning backbone peptide bonds. The partitioning cost is dramatically reduced if the peptide bonds participate in hydrogen bonds. The reduced cost underlies secondary structure formation by amphiphilic peptides partitioned into membrane interfaces through a process referred to as partitioning-folding coupling. This coupling is characterized by the free energy reduction per residue, ∆G(res) that drives folding. There is some debate about the correct value of ∆G(res) and its dependence on the hydrophobic moment (μ(H)) of amphiphilic α-helical peptides. We show how to compute ∆G(res) correctly. Using published data for two families of peptides with different hydrophobic moments and charges, we find that ∆G(res) does not depend upon μ(H). The best estimate of ∆G(res) is -0.37 ± 0.02 kcal mol(-1). This article is part of a Special Issue entitled: Membrane protein structure and function.
由于将肽主链键分配到膜界面的成本，许多未折叠肽分配到膜界面的自由能成本ΔG是不利的。如果肽键参与氢键形成，分配成本会显著降低。这种降低的成本是两亲性肽通过一种称为分配-折叠偶联的过程分配到膜界面时二级结构形成的基础。这种偶联的特征是每个残基的自由能降低，即驱动折叠的∆G(res)。关于∆G(res)的正确值及其对两亲性α-螺旋肽疏水矩(μ(H))的依赖性存在一些争议。我们展示了如何正确计算∆G(res)。利用已发表的具有不同疏水矩和电荷的两个肽家族的数据，我们发现∆G(res)不依赖于μ(H)。∆G(res)的最佳估计值为-0.37±0.02千卡摩尔(-1)。本文是名为：膜蛋白结构与功能的特刊的一部分。
