School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, 695551, India.
Angew Chem Int Ed Engl. 2022 Jan 21;61(4):e202113129. doi: 10.1002/anie.202113129. Epub 2021 Nov 22.
Tuning the secondary structure of a protein or polymer in the solid-state is challenging. Here we report the topochemical synthesis of a pseudoprotein and its secondary structure tuning in the solid-state. We designed the dipeptide monomer N -Leu-Ala-NH-CH -C≡CH (1) for topochemical azide-alkyne cycloaddition (TAAC) polymerization. Dipeptide 1 adopts an anti-parallel β-sheet-like stacked arrangement in its crystals. Upon heating, the dipeptide undergoes quantitative TAAC polymerization in a crystal-to-crystal fashion yielding large polymers. The reaction occurs between the adjacent monomers in the H-bonded anti-parallel stack, yielding pseudoprotein having a β-meander structure. When dissolved in methanol, this pseudoprotein changes its secondary structure from β-meander to α-helical form and it retains the new secondary structure upon desolvation. This work demonstrates a novel paradigm for tuning the secondary structure of a polymer in the solid-state.
在固态中调整蛋白质或聚合物的二级结构具有挑战性。在这里，我们报告了一种伪蛋白的拓扑化学合成及其在固态中的二级结构调谐。我们设计了二肽单体 N -Leu-Ala-NH-CH -C≡CH（1）用于拓扑化学叠氮-炔烃环加成（TAAC）聚合。二肽 1 在其晶体中采取反平行 β-折叠样堆积排列。加热时，二肽在晶体到晶体的方式下发生定量 TAAC 聚合，生成大聚合物。反应发生在相邻单体之间的氢键反平行堆叠中，生成具有 β-曲折结构的伪蛋白。当溶解在甲醇中时，这种伪蛋白的二级结构从β-曲折转变为α-螺旋形式，并且在去溶剂化后保留新的二级结构。这项工作展示了在固态中调整聚合物二级结构的新范例。
