Assembly of type I collagen fibrils de novo. Between 37 and 41 degrees C the process is limited by micro-unfolding of monomers.
Assembly of type I collagen fibrils de novo. Between 37 and 41 degrees C the process is limited by micro-unfolding of monomers.
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发表时间：
1988-07
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通讯作者：
K. Kadler;Y. Hojima;D. Prockop
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作者：
K. Kadler;Y. Hojima;D. Prockop
温度对胶原原纤维组装的影响进行了研究，在一个系统中，其中胶原单体从头产生，并在生理缓冲液中通过特异性酶裂解的I型PC-胶原，中间体在正常的加工过程中的I型前胶原的I型胶原。在29-35 ° C范围内增加反应温度降低了浊度滞后并增加了通过浊度测定的增长速率。温度对浊度传播速率的影响给出了具有负斜率的线性Arrhenius图。增长活化能的预测值为113 kJ/mol。然而，温度对高于37 ℃的组装速率的影响与在低于37 ℃的温度下观察到的影响相反。在37-41 ℃范围内，浊度传播速率随温度显著降低。此外，浊度滞后增加。因此，单体与原纤维达到平衡需要长得多的时间。在高于37 ° C的温度下保留在溶液中的大部分胶原单体对胰蛋白酶和α-糜蛋白酶的快速消化敏感。将溶液冷却至25 ° C使得单体对蛋白酶消化具有抗性。结果是一致的结论，虽然胶原纤维的形成是一个经典的例子，熵驱动的过程中的自组装，组装率在37和41摄氏度之间的限制由可逆的微观展开的单体。
The effects of temperature on the assembly of collagen fibrils were examined in a system in which collagen monomers are generated de novo and in a physiological buffer by specific enzymic cleavage of type I pC-collagen, an intermediate in the normal processing of type I procollagen to type I collagen. Increasing the temperature of the reaction in the range of 29-35 degrees C decreased the turbidity lag and increased the rate of propagation as assayed by turbidity. The effect of temperature on the turbidity propagation rate gave a linear Arrhenius plot with a negative slope. The predicted value of the activation energy of propagation was 113 kJ/mol. However, the effects of temperature on the rate of assembly above 37 degrees C were opposite to the effects seen at temperatures below 37 degrees C. In the range of 37-41 degrees C, the turbidity propagation rate decreased markedly with temperature. Also, the turbidity lag increased. Therefore, much longer times were required for monomers to reach equilibrium with fibrils. A large fraction of the collagen monomers remaining in solution at temperatures above 37 degrees C was sensitive to rapid digestion by trypsin and alpha-chymotrypsin. Cooling the solutions to 25 degrees C made the monomers resistant to protease digestion. The results are consistent with the conclusion that, although formation of collagen fibrils is a classical example of an entropy-driven process of self-assembly, the rate of assembly between 37 and 41 degrees C is limited by reversible micro-unfolding of the monomer.