Evidence for an elementary process in bone plasticity with an activation enthalpy of 1 eV
Evidence for an elementary process in bone plasticity with an activation enthalpy of 1 eV
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DOI：
10.1098/rsif.2006.0172
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发表时间：
2007-04-22
影响因子：
3.9
通讯作者：
Kirchner, Helmut O. K.
中科院分区：
文献类型：
--
作者：
Gupta, Himadri S.;Fratzl, Peter;Kirchner, Helmut O. K.
骨组织塑性变形的分子机制尚不清楚。我们使用最初用于研究金属塑性变形的技术，分析了纤维板层骨中拉伸变形行为的温度和应变率依赖性。我们表明，在弹性状态之外，骨具有高度应变率敏感性，其激活体积约为0.6 nm(3)。我们发现在分子水平上，与骨塑性变形的基本步骤相关的活化能为1.1 eV。这比氢键的能量要高得多，但比破坏胶原原纤维内部共价键所需的能量要低。基于这些量的大小，我们推测骨纤维外基质中聚电解质分子之间静电键的破坏，可能是由多价离子（如钙）介导的，可能是骨可塑性的速率限制的基本步骤。
The molecular mechanisms for plastic deformation of bone tissue are not well understood. We analysed temperature and strain-rate dependence of the tensile deformation behaviour in fibrolamellar bone, using a technique originally developed for studying plastic deformation in metals. We show that, beyond the elastic regime, bone is highly strain-rate sensitive, with an 3 activation volume of ca 0.6 nm(3). We find an activation energy of 1.1 eV associated with the basic step involved in the plastic deformation of bone at the molecular level. This is much higher than the energy of hydrogen bonds, but it is lower than the energy required for breaking covalent bonds inside the collagen fibrils. Based on the magnitude of these quantities, we speculate that disruption of electrostatic bonds between polyelectrolyte molecules in the extrafibrillar matrix of bone, perhaps mediated by polyvalent ions such as calcium, may be the rate-limiting elementary step in bone plasticity.