Liu Lichao, Wang Han, Han Yueying, Lv Shanshan, Chen Jianfeng
State Key Laboratory of Organic-Inorganic Composite Materials, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing 100029, China.
J Mater Chem B. 2018 Aug 28;6(32):5303-5312. doi: 10.1039/c8tb01511b. Epub 2018 Aug 7.
This study demonstrated that incorporation of Ca-responsive β-roll peptides arising from repeat-in-toxin (RTX) into elastomeric proteins provided an approach to construct hydrogels that exhibit Ca-responsive mechanical properties through a force analysis-based approach. Use of circular dichroism spectroscopy confirmed that there was a Ca-induced conformational change of RTX-based recombinant polyproteins. The polyproteins could be crosslinked into solid hydrogels. Shrinking/swelling measurements showed a Ca-responsive dimensional change of the RTX-based hydrogels. Mechanical measurements at constant pulling speed and at constant extension suggested that the mechanical properties of the RTX-based hydrogels were Ca-responsive. Experimental single molecule force spectroscopies were used to investigate the nano-mechanical stability of the RTX domains. Single molecule atomic force microscopy and optical tweezers provided evidence that the Ca-dependent refolding of the intrinsically disordered RTX led to the force increase. The results indicated that the unique Ca-responsive mechanical properties of the RTX-based hydrogels at the macroscopic level could be attributed to the nano-mechanical properties of the RTX domains engineered into individual polyproteins at the single molecule level.
本研究表明，将源自重复毒素（RTX）的钙响应性β-螺旋肽掺入弹性蛋白中，提供了一种通过基于力分析的方法构建具有钙响应机械性能的水凝胶的途径。圆二色光谱法的使用证实，基于RTX的重组多蛋白存在钙诱导的构象变化。这些多蛋白可以交联成固态水凝胶。收缩/膨胀测量表明基于RTX的水凝胶存在钙响应的尺寸变化。在恒定拉伸速度和恒定伸长率下的力学测量表明，基于RTX的水凝胶的机械性能是钙响应性的。实验性单分子力谱用于研究RTX结构域的纳米机械稳定性。单分子原子力显微镜和光镊提供了证据，表明内在无序的RTX的钙依赖性重折叠导致力增加。结果表明，基于RTX的水凝胶在宏观水平上独特的钙响应机械性能可归因于在单分子水平上工程化到单个多蛋白中的RTX结构域的纳米机械性能。
