Electrostatic effects in collagen fibril formation
Electrostatic effects in collagen fibril formation
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DOI：
10.1063/1.5036526
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发表时间：
2018-10-28
影响因子：
4.4
通讯作者：
Muthukumar, Murugappan
中科院分区：
文献类型：
--
作者：
Morozova, Svetlana;Muthukumar, Murugappan
利用光散射和原子力显微镜技术，我们研究了与人眼玻璃体有关的胶原结合的动力学和平衡散射强度。具体地说，我们已经表征了熔化对pH、温度和离子强度的依赖。在较高和较低pH下，胶原蛋白三螺旋在溶液中保持稳定，不发生纤化。在生理pH下，随着离子强度的增加或温度的降低，纤维发生纤化并减缓原纤维的生长。在这些条件下，相对于离子强度的总光散射是非单调的，这是由于纤维浓度和尺寸与离子强度的竞争关系的结果。纤维浓度在低离子强度时最高，在高离子强度时迅速衰减。另一方面，在离子强度较高的溶液中，纤维尺寸较大。我们提出了一个理论模型，基于溶液中的偶极相互作用，来描述观察到的胶原蛋白组装的静电性质。在极端的pH值下，无论是非常低的还是非常高的，胶原蛋白三螺旋都携带着相同符号的大净电荷，防止它们组装成纤维。在中等pH值时，胶原蛋白三螺旋的电荷分布在大约零净电荷附近的波动会导致纤维化。由电荷涨落引起的偶极相互作用可以很好地描述纤维在这一区域的生长动力学。由AIP出版公司出版。
Using light scattering and Atomic Force Microscopy techniques, we have studied the kinetics and equilibrium scattering intensity of collagen association, which is pertinent to the vitreous of the human eye. Specifically, we have characterized fibrillization dependence on pH, temperature, and ionic strength. At higher and lower pH, collagen triple helices remain stable in solution without fibrillization. At physiological pH, fibrillization occurs and the fibril growth is slowed upon either an increase in ionic strength or a decrease in temperature. The total light scattering with respect to ionic strength is non-monotonic in these conditions as a result of a competing dependence of fibril concentration and size on ionic strength. Fibril concentration is the highest at lower ionic strengths and rapidly decays for higher ionic strengths. On the other hand, fibril size is larger in solutions with higher ionic strength. We present a theoretical model, based on dipolar interactions in solutions, to describe the observed electrostatic nature of collagen assembly. At extreme pH values, either very low or very high, collagen triple helices carry a large net charge of the same sign preventing their assembly into fibrils. At intermediate pH values, fluctuations in the charge distribution of the collagen triple helices around roughly zero net charge lead to fibrillization. The growth kinetics of fibrils in this regime can be adequately described by dipolar interactions arising from charge fluctuations. Published by AIP Publishing.