Evolved proteins observed in natural organisms are found to be only marginally stable. Several mechanistic hypotheses have been presented to date to explain this observation. One idea that has been put forward is that active selection prevents proteins from becoming too stable to enable proper function. A second idea is that marginal stability reflects the point of mutation–selection–drift balance, where it is mutational pressure that generates marginal stability. A third idea explored in this issue of Journal of Molecular Evolution is that a physical limit prevents the evolution of more stable proteins rather than an evolutionary process. While the first two notions are based upon specific evolutionary processes, discussion here is aimed at reconciling evolutionary processes with the physics of protein folding, drawing upon the ideas that have been presented.

发现在自然生物中观察到的进化蛋白质仅略微稳定。迄今为止，已经提出了几种机械假设来解释这一观察结果。已经提出的一个想法是主动选择可以防止蛋白质变得太稳定而无法正常发挥作用。第二个想法是边际稳定性反映了突变-选择-漂移平衡点，在那里产生边际稳定性的是突变压力。本期《Journal of Molecular Evolution》探讨的第三个想法是物理限制阻止了更稳定的蛋白质的进化，而不是进化过程。虽然前两个概念基于特定的进化过程，但这里的讨论旨在协调进化过程与蛋白质折叠物理学，利用已经提出的想法。