Sasaki N, Odajima S
Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan.
J Biomech. 1996 Sep;29(9):1131-6. doi: 10.1016/0021-9290(96)00024-3.
Tension-induced structural changes in bovine Achilles tendon collagen at each level of the hierarchy structure were investigated by means of the X-ray diffraction method. In order to estimate the straining mechanism in a collagen fibril, three elementary models for molecular elongation and rearrangement of collagen fibril were proposed on the basis of the Hodge-Petruska model: [1] molecular elongation, [2] increase in gap region and [3] relative slippage of laterally adjoining molecules. The characteristic 67 nm D-period of a collagen fibril increases with applied force. A Hookean-type force-strain curve was obtained for the D-period while the force-strain relation for the tendon was non-Hookean. The relative intensity of third-order reflection of the D-period to that of the second-order one, I3/I2, decreased with the applied force. This decrease in I3/I2 indicates a decrease in the ratio of the overlap region of collagen fibril to the D-period, O/D, which was analyzed on the basis of the Hodge-Petruska model. Decomposition of the observed strain in the D-period, epsilon(D), into these three deforming modes revealed that the major contribution to epsilon(D) originated from mode [1], molecular elongation. It was deduced that a fibril is mechanically composed of molecules connected serially to each other.
采用X射线衍射法研究了牛跟腱胶原在各级层次结构上由张力诱导产生的结构变化。为了估计胶原纤维中的应变机制，在霍奇 - 彼得鲁斯卡模型的基础上提出了三种胶原纤维分子伸长和重排的基本模型：[1]分子伸长，[2]间隙区域增加，[3]横向相邻分子的相对滑动。胶原纤维特有的67nm D周期随施加力的增加而增大。D周期获得了胡克型力 - 应变曲线，而肌腱的力 - 应变关系是非胡克型的。D周期的三阶反射与二阶反射的相对强度I3/I2随施加力的增加而降低。I3/I2的这种降低表明胶原纤维重叠区域与D周期的比值O/D降低，这是基于霍奇 - 彼得鲁斯卡模型进行分析的。将D周期中观察到的应变ε(D)分解为这三种变形模式，结果表明对ε(D)的主要贡献来自模式[1]，即分子伸长。由此推断，纤维在力学上是由彼此串联连接的分子组成的。
