Entropic elasticity controls nanomechanics of single tropocollagen molecules
Entropic elasticity controls nanomechanics of single tropocollagen molecules
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DOI：
10.1529/biophysj.106.102616
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发表时间：
2007-07-01
影响因子：
3.4
通讯作者：
Wong, Sophie Y.
中科院分区：
文献类型：
--
作者：
Buehler, Markus J.;Wong, Sophie Y.
我们报告了拉伸原胶原单分子的分子模型，原胶原是胶原蛋白、原纤维和纤维的组成部分，为结缔组织提供机械支撑。对于小变形，我们观察到熵弹性占主导地位。在较大变形时，我们。向能量弹性的转变，其特征是氢键首先拉伸和断裂，然后蛋白质主链中的共价键变形，最终导致分子断裂。我们的小力下的力-位移曲线与光镊实验显示出极好的定量一致性。我们的模型预测持久长度 xi(p) 大约为 16 nm，con。实验结果表明，原胶原分子是非常大的。柔韧的弹性实体。我们证明，将单个原胶原分子组装成原纤维可显着降低其弯曲度。柔韧性，导致变形过程中熵效应的贡献减少。分子模拟结果用于开发一个简单的连续体模型，能够描述原胶原分子的整个变形范围。我们的分子模型能够描述不同的弹性和永久变形状态，而不依赖于经验参数，包括从熵弹性到能量弹性的转变。
We report molecular modeling of stretching single molecules of tropocollagen, the building block of collagen, fibrils and fibers that provide mechanical support in connective tissues. For small deformation, we observe a dominance of entropic elasticity. At larger deformation, we. nd a transition to energetic elasticity, which is characterized by first stretching and breaking of hydrogen bonds, followed by deformation of covalent bonds in the protein backbone, eventually leading to molecular fracture. Our force-displacement curves at small forces show excellent quantitative agreement with optical tweezer experiments. Our model predicts a persistence length xi(p) approximate to 16 nm, con. rming experimental results suggesting that tropocollagen molecules are very. exible elastic entities. We demonstrate that assembly of single tropocollagen molecules into fibrils significantly decreases their bending. exibility, leading to decreased contributions of entropic effects during deformation. The molecular simulation results are used to develop a simple continuum model capable of describing an entire deformation range of tropocollagen molecules. Our molecular model is capable of describing different regimes of elastic and permanent deformation, without relying on empirical parameters, including a transition from entropic to energetic elasticity.