Szoszkiewicz Robert
Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw Żwirki i Wigury 101 02-089 Warsaw Poland
RSC Adv. 2025 Jan 27;15(4):2717-2726. doi: 10.1039/d4ra08047e. eCollection 2025 Jan 23.
One of still outstanding issues in protein folding is to be able to directly observe structural changes occurring along the folding pathway. Herein, we report on changes of the viscoelastic properties for a single protein molecule measured along its mechanically-induced unfolding and refolding trajectories. We use a model system, the I27 poly-protein, and investigate its conformational changes force-clamp AFM (FC-AFM) spectroscopy. Typically only protein's length and force have been measured using this approach. By applying Euler-Bernoulli model of the AFM cantilever with properly accounted hydrodynamic damping we show how to access - from the same measurements - related changes of two additional observables such as molecular stiffness and molecular friction coefficient. Our results are compared to recent analytical models and experimental results. These findings are expected to lead to proper identification of the intermediate folding states from the knowledge of their mechanical properties.
蛋白质折叠领域中仍未解决的突出问题之一是能够直接观察沿折叠途径发生的结构变化。在此，我们报告了单个蛋白质分子在机械诱导的解折叠和重折叠轨迹上测量的粘弹性特性的变化。我们使用一个模型系统，即I27多聚蛋白，并通过力钳原子力显微镜（FC-AFM）光谱研究其构象变化。通常，使用这种方法仅测量了蛋白质的长度和力。通过应用适当考虑了流体动力学阻尼的AFM悬臂的欧拉 - 伯努利模型，我们展示了如何从相同的测量中获取另外两个可观测量的相关变化，例如分子刚度和分子摩擦系数。我们的结果与最近的分析模型和实验结果进行了比较。这些发现有望通过了解中间折叠态的机械特性来正确识别它们。
