Glassy dynamics and memory effects in an intrinsically disordered protein construct

Glassy, nonexponential relaxations in globular proteins are typically attributed to conformational behaviors that are missing from intrinsically disordered proteins. Yet, we show that single molecules of a disordered-protein construct display two signatures of glassy dynamics, logarithmic relaxations and a Kovacs memory effect, in response to changes in applied tension. We attribute this to the presence of multiple independent local structures in the chain, which we corroborate with a model that correctly predicts the force-dependence of the relaxation. The mechanism established here likely applies to other disordered proteins.

球状蛋白质中普遍存在的玻璃态非指数弛豫，通常被归因于内在无序蛋白质（intrinsically disordered proteins）所不具备的构象行为。然而本研究表明，某一无序蛋白质构建体的单分子在响应施加张力变化时，展现出玻璃态动力学的两大特征：对数弛豫与科瓦茨记忆效应（Kovacs memory effect）。我们将该现象归因于多肽链中存在多个独立的局部结构，并通过一个可准确预测弛豫力依赖性的模型验证了这一推论。本文所阐明的这一机制，大概率也适用于其他无序蛋白质。