Ciferri Alberto, Crumbliss Alvin L
Chemistry Department, Duke University, Durham, NC, United States.
Front Chem. 2019 Jul 16;7:487. doi: 10.3389/fchem.2019.00487. eCollection 2019.
Extended linear structures self-assemble by the multi-stage-open-association mechanism of supramolecular polymerization (MSOA). Application of the model requires the identification of a repeating unit, the main-chain supramolecular bond, and the binding constant. The strength of the bond and the degree of polymerization become extremely large when multiple sites for non-covalent interactions occur. These expectations had been previously verified in the case of the neuronal axon, for which the above parameters were assessed from its known molecular structure. The more complex case of the myofibril is analyzed here. The specific interactions that connect neighboring sarcomers have been a matter of debate. Recent work has focused on the bond between titin and α-actinin localized at the terminal Z-zones of each sarcomer. Elaboration of literature data suggests that titin-α-actinin interactions do bridge neighboring sarcomers, promoting the polymerization of myofibrils that attain macroscopic dimensions consistently with the MSOA predictions. The rationale for the complex structuration of single sarcomers is discussed.
扩展线性结构通过超分子聚合的多阶段开放缔合机制（MSOA）进行自组装。该模型的应用需要确定重复单元、主链超分子键和结合常数。当存在多个非共价相互作用位点时，键的强度和聚合度会变得极大。这些预期先前已在神经元轴突的案例中得到验证，其上述参数可根据已知分子结构进行评估。本文分析了更复杂的肌原纤维案例。连接相邻肌节的特定相互作用一直是个有争议的问题。近期的研究工作聚焦于肌联蛋白与定位于每个肌节末端Z区的α -辅肌动蛋白之间的键。对文献数据的详细分析表明，肌联蛋白 - α -辅肌动蛋白相互作用确实连接了相邻肌节，促进了肌原纤维的聚合，其聚合后的宏观尺寸与MSOA预测结果一致。本文还讨论了单个肌节复杂结构形成的原理。
