Department of Chemistry, University of Dayton, Dayton, Ohio.
Chirality. 2020 Jan;32(1):5-16. doi: 10.1002/chir.23140. Epub 2019 Nov 11.
In this study, we performed an ultraviolet-visible (UV-Vis) and circular dichroism (CD) spectroscopic analysis of the binary and ternary supramolecular structures formed by self-assembling the following three water-soluble porphyrins with and without a chiral template: the negatively charged, meso-Tetra(4-sulfonatophenyl) porphine (H TPPS ); the positively charged meso-trans-(di(N-methyl-4-pyridyl)diphenyl) porphine (trans-DmPyDPP) and meso-cis-(di(N-methyl-4-pyridyl)diphenyl) porphine (cis-DmPyDPP). Polyglutamic acid (both L and D enantiomers) was selected as the chiral template due to its ability to change secondary structure with pH. The propensity for the porphyrins to show an induced CD in the presence of polyglutamic acid is demonstrated. The induced chirality of all supramolecular structures was found to depend on the pH of the solution, the chirality of the polymer, and the order of addition of the positively and negatively charged porphyrins (for ternary complexes). Of particular interest is that the interaction of H TPPS with the chiral scaffold seems to undergo a dynamic rearrangement of the supramolecular structure as evident from the change in the CD spectrum over time. Moreover, experiments with ternary complexes suggest that the preferential interaction of trans-DmPyDPP with the random coil of the polymer shows promise as a sensor of protein secondary structure.
在这项研究中，我们通过自组装三种水溶性卟啉（带和不带手性模板）来进行二元和三元超分子结构的紫外-可见（UV-Vis）和圆二色（CD）光谱分析：带负电荷的、meso-四（4-磺酸钠苯基）卟啉（H TPPS）；带正电荷的meso-trans-（二（N-甲基-4-吡啶基）二苯基）卟啉（trans-DmPyDPP）和 meso-cis-（二（N-甲基-4-吡啶基）二苯基）卟啉（cis-DmPyDPP）。聚谷氨酸（L 和 D 两种对映体）被选为手性模板，因为它能够随 pH 值改变二级结构。证明了在聚谷氨酸存在下卟啉显示诱导 CD 的倾向。所有超分子结构的诱导手性被发现取决于溶液的 pH 值、聚合物的手性以及带正电荷和带负电荷卟啉的添加顺序（对于三元配合物）。特别有趣的是，H TPPS 与手性支架的相互作用似乎经历了超分子结构的动态重排，这可以从 CD 光谱随时间的变化中看出。此外，三元配合物的实验表明，trans-DmPyDPP 与聚合物无规卷曲的优先相互作用有望成为蛋白质二级结构的传感器。
