QUANTITATIVE-ANALYSES OF HYDROPHOBICITY OF DIPEPTIDES TO PENTAPEPTIDES HAVING UN-IONIZABLE SIDE-CHAINS WITH SUBSTITUENT AND STRUCTURAL PARAMETERS
QUANTITATIVE-ANALYSES OF HYDROPHOBICITY OF DIPEPTIDES TO PENTAPEPTIDES HAVING UN-IONIZABLE SIDE-CHAINS WITH SUBSTITUENT AND STRUCTURAL PARAMETERS
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DOI：
10.1002/jps.2600810213
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发表时间：
1992-02-01
影响因子：
3.8
通讯作者：
FUJITA, T
中科院分区：
文献类型：
--
作者：
AKAMATSU, M;FUJITA, T
在最近建立的实验条件下，我们测量了由具有不可电离侧链的氨基酸组成的124种二肽与五肽在1-辛醇：pH 7.0磷酸盐缓冲水溶液系统中的分配比（P '），作为近似的两性离子化"分子"分配系数（P）。经验方程的质量好，相关的变化在log P '值的肽与自由能相关的物理化学参数的侧链取代基和子结构，制定。显着的侧链参数是那些代表固有的疏水性，空间位阻效应的相对溶剂化的功能基团的骨干，和来自Chou-Fasman β-转角电位参数的构象电位指数。对于极性侧链，需要特定的指标变量的分子内氢键的形成和“极性邻近效应”的减少时，观察到的亲水性极性基团拥挤在一起。脯氨酸残基被证明有助于log P '值，这不仅取决于其在主链上的位置，而且取决于肽中残基的数量。在此基础上，我们提出了一个新的非离子化侧链的“有效”疏水性指数，可以用来预测寡肽的二级结构。
With experimental conditions established recently, we measured the partition ratio (P') of 124 di- to pentapeptides composed of amino acids having un-ionizable side chains in a 1-octanol:pH 7.0 aqueous phosphate buffer system as an approximate zwitterionized "molecular" partition coefficient (P). Empirical equations of good quality, correlating the variations in log P' value of peptides with free energy-related physicochemical parameters for the side chain substituents and substructures, were formulated. The significant side chain parameters were those representing the intrinsic hydrophobicity, the steric effect on the relative solvation of functional groups on the backbone, and the conformational potential index derived from the Chou-Fasman beta-turn potential parameters. For polar side chains, specific indicator variables were required for intramolecular hydrogen-bond formations and the "polar proximity effect" for reductions of hydrophilicity observed when polar groups are crowded together. The proline residue was shown to contribute to the log P' value depending not only on its location on the backbone but also on the number of residues in peptides. On the basis of the analyses, we proposed a new "effective" hydrophobicity index for un-ionizable side chains which could predict the secondary structure of oligopeptides.