Site-specific infrared dichroism is an emerging method capable of proposing a model for the backbone structure of a transmembrane α-helix within a helical bundle. Dichroism measurements of single, isotopically enhanced vibrational modes (e.g., Amide I 13C=18O or Gly CD2 stretching modes) can yield precise orientational restraints for the monomer helix protomer that can be used as refinement constraints in model building of the entire helical bundle. Essential, however, for the interpretation of the dichroism measurements, is an accurate modeling of the sample disorder. In this study we derive an enhanced and more realistic modeling of the sample disorder based on a Gaussian distribution of the chromophore around a particular angle. The enhanced utility of the Gaussian model is exemplified by the comparative data analysis based on the aforementioned model to previously employed models.
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机译：特定位置的红外二向色性是一种新兴的方法，能够为螺旋束内跨膜α-螺旋的骨架结构提出模型。单一同位素增强振动模式（例如，酰胺I 13 C = 18 O或Gly CD2拉伸模式）的二向色性测量可以产生精确的单体螺旋取向约束可以用作整个螺旋束模型构建中的细化约束。但是，对二色性测量值的解释必不可少的是对样本疾病的准确建模。在这项研究中，我们基于发色团在特定角度附近的高斯分布，推导了增强的，更逼真的样本异常建模。高斯模型的增强的效用通过基于前述模型与先前采用的模型的比较数据分析来举例说明。
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