Standardizing the free energy change of transmembrane helix-helix interactions
Standardizing the free energy change of transmembrane helix-helix interactions
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DOI：
10.1016/s0022-2836(02)00920-8
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发表时间：
2002-10-25
影响因子：
5.6
通讯作者：
Fleming, KG
中科院分区：
文献类型：
--
作者：
Fleming, KG
跨膜α-螺旋的侧向结合是螺旋膜蛋白结构和功能的重要组成部分。在对推动跨膜α-螺旋之间横向相互作用的化学原理的理解中，一个基本未知的问题是多肽序列与疏水溶剂之间的作用力平衡。为了开始解决这个问题，考虑到基本热力学原理已经被应用于评估与胶束中跨膜螺旋二聚相关的实验自由能变化。这一分析证明了将跨膜螺旋-螺旋缔合的表观自由能分成两部分的能力。第一个分量是统计能量项，它产生于反应物和产物的数量不相等的事实。第二组分是标准态自由能变化，它通知跨膜螺旋自缔合反应的分子细节。分离这两个能量项的好处来自于这样一个事实，即对标准状态自由能变化的外推使统计能量项归一化，从而使其在所有实验系统中同等适用。伴随着血糖素A跨膜α-螺旋二聚体在胶束中测量的实验结果，在理想稀释溶液的假设下，这些理论成分可以很好地描述。(C)2002爱思唯尔科学有限公司。保留所有权利。
Side-to-side associations of transmembrane a-helices are integral components of the structure and function of helical membrane proteins. A fundamental unknown in the understanding of the chemical principles driving the lateral interactions between transmembrane alpha-helices is the balance of forces arising from the polypeptide sequence versus the hydrophobic solvent. To begin to address this question, a consideration of basic thermodynamic principles has been applied to assess the experimental free energy change associated with transmembrane helix dimerization in micelles. This analysis demonstrates the ability to partition the apparent free energy of transmembrane helix-helix association into two components. The first component is a statistical energy term, which arises from the fact that there are an unequal number of reactants and products. The second component is a standard state free energy change, which informs on the molecular details of the transmembrane helix self-association reaction. The advantage of separating these two energy terms arises from the fact that extrapolation to the standard state free energy change normalizes the statistical energy term so that it applies equivalently in all experimental systems. Accompanying experimental results for the glycophorin A transmembrane alpha-helix dimer measured in micelles are well described by these theoretical components assuming an ideal-dilute solution. (C) 2002 Elsevier Science Ltd. All rights reserved.