Relating the native fold of a protein to its amino acid sequence remains a fundamental problem in biology. While computer algorithms have demonstrated recently their prowess in predicting what structure a particular amino acid sequence will fold to, an understanding of how and why a specific protein fold is achieved remains elusive. A major challenge is to define the role of conformational heterogeneity during protein folding. Recent experimental studies, utilizing time-resolved FRET, hydrogen-exchange coupled to mass spectrometry, and single-molecule force spectroscopy, often in conjunction with simulation, have begun to reveal how conformational heterogeneity evolves during folding, and whether an intermediate ensemble of defined free energy consists of different sub-populations of molecules that may differ significantly in conformation, energy and entropy.

将蛋白质的天然折叠与其氨基酸序列联系起来仍然是生物学中的一个基本问题。虽然计算机算法最近已经证明了它们在预测特定氨基酸序列将折叠成什么结构方面的能力，但对如何以及为何实现特定蛋白质折叠的理解仍然难以捉摸。一个主要的挑战是定义构象异质性在蛋白质折叠过程中的作用。最近的实验研究利用时间分辨FRET、氢交换与质谱联用以及单分子力谱，通常与模拟相结合，已经开始揭示构象异质性在折叠过程中如何演变，以及是否存在定义自由的中间系综。能量由不同的分子亚群组成，这些分子亚群在构象、能量和熵方面可能存在显着差异。