Distance distributions of end-labeled curved bispeptide oligomers by electron spin resonance
Distance distributions of end-labeled curved bispeptide oligomers by electron spin resonance
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DOI：
10.1021/nn800327g
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发表时间：
2008-09-01
期刊：
影响因子：
17.1
通讯作者：
Schafmeister, Christian E.
中科院分区：
文献类型：
--
作者：
Bird, Gregory H.;Pornsuwan, Soraya;Schafmeister, Christian E.
我们演示了一系列自旋标记的弯曲低聚物的合成，以使用电子自旋共振确定它们的端到端长度和距离分布。我们从构象受限的不对称单体合成形状持久的大分子，这些单体通过酰胺键对偶联，形成具有明确三维结构的水溶性螺梯低聚物。我们合成了七种不同的大分子，每种大分子包含八个单体，但序列不同，以产生具有不同弯曲形状的大分子。低聚物的末端用氮氧自旋探针标记，并进行双电子-电子共振(DEER)电子自旋共振(ESR)实验，以获得有关低聚物形状和柔性的定量信息。低聚物最可能的端到端距离范围为 23 至 36 埃，这是我们之前通过组装包含 4-8 个双氨基酸单体的棒状同质低聚物获得的长度范围。测量的低聚物的相对距离证实，通过改变低聚物的序列，我们能够控制其形状。 ESR 衍生的群体分布的形状使我们能够将螺梯低聚物的形状持久性和灵活性程度与其他经过充分研究的纳米级分子结构（如对苯基乙炔）进行比较。
We demonstrate the synthesis of a series of spin-labeled curved oligomers to determine their end-to-end lengths and distance distributions using electron spin resonance. We synthesize shape-persistent macromolecules from conformationally restricted, asymmetric monomers that are coupled through pairs of amide bonds to create water-soluble, spiro-ladder oligomers with well-defined three-dimensional structures. We synthesized seven different macromolecules, each containing eight monomers but differing in the sequence to create macromolecules with different curved shapes. The ends of the oligomers were labeled with nitroxide spin probes, and double electron-electron resonance (DEER) electron spin resonance (ESR) experiments were carried out to obtain quantitative information about the shapes and flexibility of the oligomers. The most probable end-to-end distance of the oligomers ranges from 23 to 36 angstrom, a range of length that we previously accessed by assembling rod-like homo-oligomers that contain 4-8 bisamino acid monomers. The relative distances measured for the oligomers confirm that, by varying the sequence of an oligomer, we are able to control its shape. The shapes of the ESR-derived population distributions allow us to compare the degree of shape persistence and flexibility of spiro-ladder oligomers to other well-studied nanoscale molecular structures such as p-phenylethynylenes.