α-helices are deformable secondary structural components regularly observed in protein folds. The overall flexibility of an α-helix can be resolved into constituent physical deformations such as bending in two orthogonal planes and twisting along the principal axis. We used Principal Component Analysis to identify and quantify the contribution of each of these dominant deformation modes in transmembrane α-helices, extramembrane α-helices, and α-helices in soluble proteins. Using three α-helical samples from Protein Data Bank entries spanning these three cellular contexts, we determined that the relative contributions of these modes towards total deformation are independent of the α-helix's surroundings. This conclusion is supported by the observation that the identities of the top three deformation modes, the scaling behaviours of mode eigenvalues as a function of α-helix length, and the percentage contribution of individual modes on total variance were comparable across all three α-helical samples. These findings highlight that α-helical deformations are independent of cellular location and will prove to be valuable in furthering the development of flexible templates in de novo protein design.

中文翻译：

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跨膜蛋白中α-螺旋变形的主成分分析。

α-螺旋是在蛋白质折叠中经常观察到的可变形二级结构成分。α 螺旋的整体柔韧性可以分解为组成物理变形，例如在两个正交平面上弯曲和沿主轴扭曲。我们使用主成分分析来识别和量化这些主要变形模式中的每一种在跨膜 α-螺旋、膜外 α-螺旋和可溶性蛋白质中的 α-螺旋中的贡献。使用蛋白质数据库条目中跨越这三个细胞环境的三个 α-螺旋样本，我们确定这些模式对总变形的相对贡献与 α-螺旋的周围环境无关。这一结论得到了观察结果的支持，即前三种变形模式的身份，模式特征值的缩放行为作为 α-螺旋长度的函数，以及单个模式对总方差的百分比贡献在所有三个 α-螺旋样本中都具有可比性。这些发现强调了 α 螺旋变形与细胞位置无关，并且将证明在进一步开发蛋白质从头设计中灵活模板方面是有价值的。