Hilderbrand Amber M, Taylor Phillip A, Stanzione Francesca, LaRue Mark, Guo Chen, Jayaraman Arthi, Kloxin April M
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA.
Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA.
Soft Matter. 2021 Feb 21;17(7):1985-1998. doi: 10.1039/d0sm01562h. Epub 2021 Jan 12.
Assembling peptides allow the creation of structurally complex materials, where amino acid selection influences resulting properties. We present a synergistic approach of experiments and simulations for examining the influence of natural and non-natural amino acid substitutions via incorporation of charged residues and a reactive handle on the thermal stability and assembly of multifunctional collagen mimetic peptides (CMPs). Experimentally, we observed inclusion of charged residues significantly decreased the melting temperature of CMP triple helices with further destabilization upon inclusion of the reactive handle. Atomistic simulations of a single CMP triple helix in explicit water showed increased residue-level and helical structural fluctuations caused by the inclusion of the reactive handle; however, these atomistic simulations cannot be used to predict changes in CMP melting transition. Coarse-grained (CG) simulations of CMPs at experimentally relevant solution conditions, showed, qualitatively, the same trends as experiments in CMP melting transition temperature with CMP design. These simulations show that when charged residues are included electrostatic repulsions significantly destabilize the CMP triple helix and that an additional inclusion of a reactive handle does not significantly change the melting transition. Based on findings from both experiments and simulations, the sequence design was refined for increased CMP triple helix thermal stability, and the reactive handle was utilized for the incorporation of the assembled CMPs within covalently crosslinked hydrogels. Overall, a unique approach was established for predicting stability of CMP triple helices for various sequences prior to synthesis, providing molecular insights for sequence design towards the creation of bulk nanostructured soft biomaterials.
组装肽能够创造出结构复杂的材料，其中氨基酸的选择会影响最终的性质。我们提出了一种实验与模拟相结合的协同方法，通过引入带电残基和一个反应性基团来研究天然和非天然氨基酸取代对多功能胶原模拟肽（CMPs）热稳定性和组装的影响。在实验中，我们观察到引入带电残基会显著降低CMP三螺旋的解链温度，而引入反应性基团后会进一步使其不稳定。在明确的水环境中对单个CMP三螺旋进行的原子模拟表明，引入反应性基团会导致残基水平和螺旋结构波动增加；然而，这些原子模拟无法用于预测CMP解链转变的变化。在与实验相关的溶液条件下对CMP进行的粗粒度（CG）模拟定性地显示了与CMP设计在解链转变温度方面实验相同的趋势。这些模拟表明，当引入带电残基时，静电排斥会显著使CMP三螺旋不稳定，而额外引入反应性基团并不会显著改变解链转变。基于实验和模拟的结果，对序列设计进行了优化以提高CMP三螺旋的热稳定性，并利用反应性基团将组装好的CMP掺入共价交联水凝胶中。总体而言，建立了一种独特的方法来在合成前预测各种序列的CMP三螺旋的稳定性，为设计用于创建块状纳米结构软生物材料的序列提供了分子见解。
