Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA.
Appl Spectrosc. 2010 Jun;64(6):615-26. doi: 10.1366/000370210791414434.
Vibrational circular dichroism (VCD) of a series of proteins in H(2)O solution with differing secondary structure are reported for the first time in the near-infrared (NIR) region as well as the NH-stretching region. The Fourier transform (FT) near-infrared (NIR) measurements were carried out between 6000 to 4000 cm(-1). FT-VCD measurements were simultaneously carried out for the mid-infrared (mid-IR) region from 2000 to 800 cm(-1) for direct comparison to VCD in the NIR region. The NIR VCD spectra of proteins show distinct spectral features for different protein structural motifs, indicating a valuable new method to study protein conformations. The principal VCD transitions in the NIR region are two combination bands, the amide A-II and B-II bands, of the amide A and B fundamentals with the amide II fundamental, and the second overtone of the amide II, referred to as the amide 3 x II band. VCD in the amide A and B band region consisting primarily of NH stretching motions were successfully obtained in H(2)O for the first time for an insulin fibril sample. Similar to the enhanced VCD signal observed in amide I and II regions, the amide A and B VCD of insulin fibril shows strong intensity enhancements, providing an additional valuable probe of protein fibril growth and development in solution. The relative sensitivities of the mid-IR, N-H stretching, and NIR regions are discussed.
首次报道了一系列在 H2O 溶液中具有不同二级结构的蛋白质的振动圆二色性（VCD），包括近红外（NIR）区域和 NH 伸缩区域。傅里叶变换（FT）近红外（NIR）测量在 6000 到 4000 cm-1之间进行。FT-VCD 测量同时在 2000 到 800 cm-1的中红外（mid-IR）区域进行，以便与 NIR 区域的 VCD 进行直接比较。蛋白质的 NIR VCD 光谱显示出不同蛋白质结构基序的独特光谱特征，表明这是一种研究蛋白质构象的有价值的新方法。NIR 区域的主要 VCD 跃迁是两个组合带，酰胺 A-II 和 B-II 带，由酰胺 A 和 B 的基本振动与酰胺 II 的基本振动以及酰胺 II 的第二泛音组成，称为酰胺 3 x II 带。首次在 H2O 中成功获得了胰岛素原纤维样品的酰胺 A 和 B 带区域的 VCD，该区域主要由 NH 伸缩运动组成。与酰胺 I 和 II 区域观察到的增强 VCD 信号相似，胰岛素原纤维的酰胺 A 和 B VCD 显示出强烈的强度增强，为溶液中蛋白质原纤维生长和发展提供了另一个有价值的探针。讨论了 mid-IR、N-H 伸缩和 NIR 区域的相对灵敏度。
