Site-directed dichroism as a method for obtaining rotational and orientational constraints for oriented polymers
Site-directed dichroism as a method for obtaining rotational and orientational constraints for oriented polymers
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DOI：
10.1021/ja964253x
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发表时间：
1997-09-24
影响因子：
15
通讯作者：
Brunger, AT
中科院分区：
文献类型：
--
作者：
Arkin, IT;MacKenzie, KR;Brunger, AT
我们提出了定点二色性的理论及其应用，以确定旋转和定向的多肽，如跨膜螺旋的方向限制。红外光谱二色性测量的单酰胺I振动模式对应的C-13-标记的网站内的多肽包含有关的螺旋倾斜和旋转角度的信息。通过分析肽序列上沿着的一组位点的二色性，可以很容易地提取这一信息;血型糖蛋白A的二聚体跨膜结构域中仅两个连续位点的数据产生螺旋轴相对于膜法线的倾斜和螺旋绕其轴的旋转。通过使用来自三个连续位点的二色性数据，可以获得螺旋取向参数和酰胺I跃迁偶极矩a的取向;这些参数与血型糖蛋白A肽二聚体的溶液NMR结构和a的文献值密切一致。该方法提供了选择性标记的肽的取向信息，即使在适度的分数样本顺序的条件下。
We present the theory of site-directed dichroism and its application to the determination of rotational and orientational constraints for oriented polypeptides such as transmembrane helices. Infrared spectroscopy dichroism measurements of single amide I vibrational modes corresponding to C-13-labeled sites within the polypeptide contain information about the helix tilt and rotation angles. This information is readily extracted by analysis of the dichroism of a set of sites along the peptide sequence; Data for just two consecutive sites in the dimeric transmembrane domain of glycophorin A yield the tilt of the helix axis with respect the membrane normal and the rotation of the helix about its axis. By using dichroism data from three consecutive sites, the helix orientation parameters and the orientation of the amide I transition dipole moment, a, can be obtained; the parameters are in close agreement with the solution NMR structure of the glycophorin A peptide dimer and literature values for a. The approach provides orientational information about selectively labeled peptides even under conditions of modest fractional sample order.