Elasticity of the Transition State Leading to an Unexpected Mechanical Stabilization of Titin Immunoglobulin Domains
Elasticity of the Transition State Leading to an Unexpected Mechanical Stabilization of Titin Immunoglobulin Domains
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过渡态的弹性导致肌联蛋白免疫球蛋白结构域意外的机械稳定性
DOI：
10.1002/anie.201700411
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Chen Hu
中科院分区：
文献类型：
--
作者：
Yuan Guohua;Le Shimin;Yao Mingxi;Qian Hui;Zhou Xin;Yan Jie;Chen Hu
肌动蛋白在调节肌肉被动弹性中起着关键作用，主要是通过肌节I带中大量免疫球蛋白结构域的随机展开和重折叠来实现的。原子力显微镜已经研究了Titin免疫球蛋白结构域在大于100 Pn的力范围内的展开动力学，而在较小的生理力范围内还没有测量到。通过使用磁镊子，发现TiTiN I27结构域在小于100 Pn的力下以令人惊讶的非单调方式展开，最慢的展开速率发生在22 Pn左右。我们进一步证明，考虑过渡态弹性的单展开路径模型可以重现实验结果。这些结果为肌肉组织被动弹性的调节机制提供了重要的新见解。
The giant protein titin plays a critical role in regulating the passive elasticity of muscles, mainly through the stochastic unfolding and refolding of its numerous immunoglobulin domains in the I‐band of sarcomeres. The unfolding dynamics of titin immunoglobulin domains at a force range greater than 100 pN has been studied by atomic force microscopy, while that at smaller physiological forces has not been measured before. By using magnetic tweezers, it is found that the titin I27 domain unfolds in a surprising non‐monotonic force‐dependent manner at forces smaller than 100 pN, with the slowest unfolding rate occurring around 22 pN. We further demonstrate that a model with single unfolding pathway taking into account the elasticity of the transition state can reproduce the experimental results. These results provide important novel insights into the regulation mechanism of the passive elasticity of muscle tissues.