Transition Dipoles from 1D and 2D Infrared Spectroscopy Help Reveal the Secondary Structures of Proteins: Application to Amyloids.
Transition Dipoles from 1D and 2D Infrared Spectroscopy Help Reveal the Secondary Structures of Proteins: Application to Amyloids.
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DOI：
10.1021/acs.jpcb.5b07706
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发表时间：
2015-11-05
期刊：
影响因子：
--
通讯作者：
Zanni MT
中科院分区：
文献类型：
--
作者：
Dunkelberger EB;Grechko M;Zanni MT
过渡偶极对于探测分子结构来说是一个未充分利用的量。在一个扩展的系统，如蛋白质的跃迁偶极强度调制的耦合，从而探测的结构。在这里，我们测量的绝对跃迁偶极强度的人类和大鼠胰淀素在其解决方案，聚集，膜，和胶束结合的形式，使用一维和二维红外光谱的组合。我们发现，由人类胰淀素组成的淀粉样蛋白纤维的振动模式可以跨越多达12个氨基酸，反映了最精心制备的样品中非常有序的β折叠。大鼠胰淀素的FTIR光谱在溶液、胶束和膜中几乎相同。我们发现，大鼠胰淀素的过渡偶极子是大得多时，结合胶束和膜比在溶液中，与大鼠胰淀素采用α-螺旋结构。我们解释的跃迁偶极强度的实验测量的参与率通常在理论研究中计算。聚集和膜结合蛋白质的结构可能难以用现有技术鉴定，特别是在动力学期间。这些结果表明，绝对过渡偶极子通过我们的1D/ 2D光谱方法测量可以提供重要的结构信息。
Transition dipoles are an underutilized quantity for probing molecular structures. The transition dipole strengths in an extended system like a protein are modulated by the couplings and thus probe the structures. Here we measure the absolute transition dipole strengths of human and rat amylin in their solution, aggregated, membrane, and micelleular bound forms, using a combination of 1D and 2D infrared spectroscopy. We find that the vibrational modes of amyloid fibers made of human amylin can extend across as many as 12 amino acids, reflecting very ordered β-sheets in the most carefully prepared samples. Rat amylin has FTIR spectra that are nearly identical in solution, micelles, and membranes. We show that the transition dipoles of rat amylin are much larger when bound to micelles and membranes than when in solution, consistent with rat amylin adopting an α-helical structure. We interpret the transition dipole strengths as experimental measurements of the inverse participation ratio often calculated in theoretical studies. The structure of aggregating and membrane-bound proteins can be difficult to identify with existing techniques, especially during kinetics. These results demonstrate how absolute transition dipoles measured via our 1D/ 2D spectroscopy method can provide important structural information.
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影响因子：
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