Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, PR China.
Langmuir. 2013 Aug 6;29(31):9721-6. doi: 10.1021/la402174w. Epub 2013 Jul 25.
The relationship between amino acid sequences and their resulting nanostructure has been well studied, but that between amino acid chirality and nanostructure handedness has not. Four dipeptide sodium salts with long alkyl chains derived from L- and D-alanines were synthesized. The behavior of their self-assembly into physical gels in water and THF was studied using field-emission scanning electron microscopy, circular dichroism (CD), FT-IR spectroscopy, (1)H NMR spectroscopy, and X-ray diffraction. The dipeptide salts organized into twisted nanoribbons, whose handedness was controlled by the terminal alanine chirality. The handedness of nanoribbons formed in water was opposite to that of those formed in THF. The dipeptide salts self-assembled into similar interdigitated bilayer structures in water and THF, but CD spectra of the gels indicated that the stacking of carbonyl groups was opposite. The formation of this handedness inversion is proposed to arise from the difference in interlayer distance and chiral stacking of carbonyl groups near the C-terminals.
氨基酸序列与其形成的纳米结构之间的关系已经得到了很好的研究，但氨基酸手性与其形成的纳米结构手性之间的关系还没有得到很好的研究。本文合成了四种由 L-和 D-丙氨酸衍生而来的具有长烷基链的二肽钠盐。使用场发射扫描电子显微镜、圆二色性（CD）、傅里叶变换红外光谱（FT-IR）、（1）H 核磁共振光谱（1H NMR）和 X 射线衍射研究了它们在水中和四氢呋喃（THF）中自组装成物理凝胶的行为。二肽盐组织成扭曲的纳米带，其手性由末端丙氨酸的手性控制。在水中形成的纳米带的手性与在 THF 中形成的纳米带的手性相反。二肽盐在水中和 THF 中自组装成类似的交错双层结构，但凝胶的 CD 光谱表明，羰基的堆积是相反的。这种手性反转的形成被认为是由于层间距离和 C 末端附近羰基的手性堆积的差异引起的。
