Solution structure of a conformationally restricted fully active derivative of the human relaxin-like factor.
Solution structure of a conformationally restricted fully active derivative of the human relaxin-like factor.
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人类松弛素样因子的构象限制的完全活性衍生物的溶液结构。
DOI：
10.1021/bi801412w
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发表时间：
2008
期刊：
影响因子：
2.9
通讯作者：
Led,JensJ
中科院分区：
文献类型：
--
作者：
Büllesbach,ErikaE;Hass,MathiasAS;Jensen,MaleneR;Hansen,DFlemming;Kristensen,SørenM;Schwabe,Christian;Led,JensJ
与胰岛素类似，松弛素样因子(RLF)在受体结合之前必须经历向活性形式的结构转变。因此，RLF的B链的C-末端向中央B链螺旋的表面折叠，导致两个重要的RLF受体结合位点残基--Valine B19和色氨酸B27--的部分消失。通过对完全活性的C端交联的RLF类似物与天然合成的人RLF(HRLF)的溶液结构的比较，可以清楚地看出，交联的类似物在很大程度上保留了天然蛋白质的基本折叠。这两种蛋白质都以主要和次要的构象存在，正如色氨酸B27和B链螺旋上相邻残基的多重共振所揭示的那样。值得注意的是，化学交联的RLF中的次要构象比hRLF中的要高得多。此外，与未经修饰的分子相比，在B链螺旋内观察到细微的差异，从而使交联型衍生物的氢键水平降低，并在结合位点残基ValB19处显著展宽峰。在这些观察的基础上，我们认为天然激素的溶液结构代表了一种非活性构象，并且在C端未折叠的结合构象和RLF的非活性构象之间存在着动态平衡。
Analogous to insulin, the relaxin-like factor (RLF) must undergo a structural transition to the active form prior to receptor binding. Thus, the C-terminus of the B chain of RLF folds toward the surface of the central B chain helix, causing partial obliteration of the two essential RLF receptor-binding site residues, valine B19 and tryptophan B27. Via comparison of the solution structure of a fully active C-terminally cross-linked RLF analogue with the native synthetic human RLF (hRLF), it became clear that the cross-linked analogue largely retains the essential folding of the native protein. Both proteins exist in a major and minor conformation, as revealed by multiple resonances from tryptophan B27 and adjacent residues on the B chain helix. Notably, the minor conformation is significantly more highly populated in the chemically cross-linked RLF than it is in the hRLF. In addition, compared to the unmodified molecule, subtle differences are observed within the B chain helix whereby the cross-linked derivative shows a reduced level of hydrogen bonding and significant peak broadening at the binding site residue ValB19. On the basis of these observations, we suggest that the solution structure of the native hormone represents an inactive conformer and that a dynamic equilibrium exists between the C-terminally unfolded binding conformation and the inactive conformation of the RLF.