School of Veterinary Sciences, University of Bristol, Langford, Bristol BS40 5DU, UK.
Phys Biol. 2011 Apr;8(2):026002. doi: 10.1088/1478-3975/8/2/026002. Epub 2011 Jan 24.
The state of collagen molecules in the fibres of tail tendon, skin and demineralized bone has been investigated in situ using differential scanning calorimetry (DSC). Hydroxyproline analysis and tissue digestion with bacterial collagenase and trypsin were used to confirm that the common cause of all the DSC endotherms was collagen denaturation. This occurred within a narrow temperature range in tendons, but over a wide temperature range in demineralized bone and old skin and demonstrated that in tendon and demineralized bone at least the same type I collagen molecule exists in different thermal states. Hypothesizing that this might be caused by different degrees of confinement within the fibre lattice, experiments were performed to measure the effect of changing the lattice dimensions by extracting the collagen into dilute solution with pepsin, swelling the lattice in acetic acid, and contracting the lattice by dehydration. A theoretical analysis was undertaken to predict the effect of dehydration. Results were consistent with the hypothesis, demonstrating that collagen molecules within the natural fibres of bone and old skin are located at different intermolecular spacings, revealing differences between molecules in the magnitude of either the attractive or repulsive forces controlling their separation. One potential cause of such variation is known differences in covalent cross-linking.
采用差示扫描量热法（DSC）原位研究了纤维中胶原分子的状态尾巴腱、皮肤和脱矿骨。羟脯氨酸分析和组织消化细菌胶原酶和胰蛋白酶用于确认所有 DSC 吸热的共同原因是胶原蛋白变性。这在肌腱中发生在很窄的温度范围内，但在脱矿骨和旧皮肤中发生在很宽的温度范围内，表明在肌腱和脱矿骨中，至少存在相同类型的 I 胶原分子在不同的热状态。假设这可能是由于纤维晶格内的不同程度的限制，通过用胃蛋白酶将胶原蛋白提取到稀溶液中、在乙酸中使晶格溶胀以及通过脱水使晶格收缩来测量改变晶格尺寸的效果的实验。进行了理论分析以预测脱水的效果。结果与假设一致，表明天然骨纤维和旧皮肤中的胶原分子位于不同的分子间间距，揭示了控制它们分离的吸引力或排斥力的分子大小的差异。这种变化的一个潜在原因是已知的共价交联差异。
