Strength of a weak bond connecting flexible polymer chains
Strength of a weak bond connecting flexible polymer chains
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DOI：
10.1016/s0006-3495(99)77399-6
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发表时间：
1999-05-01
影响因子：
3.4
通讯作者：
Ritchie, K
中科院分区：
文献类型：
--
作者：
Evans, E;Ritchie, K
在稳定上升的力下键解离最常发生在受加载速率控制的时间（Evans 和 Ritchie，1997 Biophys. J. 72：1541-1555）。断裂时间乘以加载速率，指定了最常见失效的力（称为粘合强度），该力遵循与加载速率相同的依赖性。粘合强度与对数（加载率）的关系图提供了解粘合过程中所经历的能量景观的图像。然而，当弱键连接到非常柔顺的元件（如长聚合物）时，施加到键上的载荷在恒定拉速下不会稳定上升。由于非稳定载荷，最常见的断裂力可能与通过刚性连接以恒定速率加载的键显着不同。使用蠕虫状和自由连接链的通用模型，我们分析了通过以恒定速度拉动聚合物连接而加载的键失效的动力学过程。我们发现，当通过任何类型的聚合物链连接时，与通过刚性连接相比，在稳定分离的情况下，键可能会在较小的力下失效。非常出乎意料的是，在长聚合物键的情况下，在缓慢的分离速度下，粘合强度可能会发生不连续的跳跃。我们证明，强度与日志（加载率）的预测可以合理化最近使用不同的力技术沿着肌肉肌腱展开 Ig 结构域所获得的相互矛盾的结果。
Bond dissociation under steadily rising force occurs most frequently at a time governed by the rate of loading (Evans and Ritchie, 1997 Biophys. J. 72:1541-1555). Multiplied by the loading rate, the breakage time specifies the force for most frequent failure (called bond strength) that obeys the same dependence on loading rate. The spectrum of bond strength versus log(loading rate) provides an image of the energy landscape traversed in the course of unbonding. However, when a weak bond is connected to very compliant elements like long polymers, the load applied to the bond does not rise steadily under constant pulling speed, Because of nonsteady loading, the most frequent breakage force can differ significantly from that of a bond loaded at constant rate through stiff linkages. Using generic models for wormlike and freely jointed chains, we have analyzed the kinetic process of failure for a bond loaded by pulling the polymer linkages at constant speed. We find that when linked by either type of polymer chain, a bond is likely to fail at lower force under steady separation than through stiff linkages. Quite unexpectedly, a discontinuous jump can occur in bond strength at slow separation speed in the case of long polymer linkages. We demonstrate that the predictions of strength versus log(loading rate) can rationalize conflicting results obtained recently for unfolding Ig domains along muscle titin with different force techniques.