Department of Biochemistry, University of Cambridge, Cambridge CB1 2GA, UK.
Q Rev Biophys. 2012 Nov;45(4):383-426. doi: 10.1017/S0033583512000108. Epub 2012 Sep 13.
Drug discovery has classically targeted the active sites of enzymes or ligand-binding sites of receptors and ion channels. In an attempt to improve selectivity of drug candidates, modulation of protein-protein interfaces (PPIs) of multiprotein complexes that mediate conformation or colocation of components of cell-regulatory pathways has become a focus of interest. However, PPIs in multiprotein systems continue to pose significant challenges, as they are generally large, flat and poor in distinguishing features, making the design of small molecule antagonists a difficult task. Nevertheless, encouragement has come from the recognition that a few amino acids - so-called hotspots - may contribute the majority of interaction-free energy. The challenges posed by protein-protein interactions have led to a wellspring of creative approaches, including proteomimetics, stapled α-helical peptides and a plethora of antibody inspired molecular designs. Here, we review a more generic approach: fragment-based drug discovery. Fragments allow novel areas of chemical space to be explored more efficiently, but the initial hits have low affinity. This means that they will not normally disrupt PPIs, unless they are tethered, an approach that has been pioneered by Wells and co-workers. An alternative fragment-based approach is to stabilise the uncomplexed components of the multiprotein system in solution and employ conventional fragment-based screening. Here, we describe the current knowledge of the structures and properties of protein-protein interactions and the small molecules that can modulate them. We then describe the use of sensitive biophysical methods - nuclear magnetic resonance, X-ray crystallography, surface plasmon resonance, differential scanning fluorimetry or isothermal calorimetry - to screen and validate fragment binding. Fragment hits can subsequently be evolved into larger molecules with higher affinity and potency. These may provide new leads for drug candidates that target protein-protein interactions and have therapeutic value.
药物发现传统上针对酶的活性位点或受体和离子通道的配体结合位点。为了提高候选药物的选择性，调节介导细胞调节途径成分构象或共定位的多蛋白复合物的蛋白质-蛋白质相互作用（PPIs）已成为关注的焦点。然而，多蛋白系统中的 PPIs 仍然存在很大的挑战，因为它们通常很大，很平坦，特征不明显，使得小分子拮抗剂的设计成为一项艰巨的任务。尽管如此，人们认识到少数氨基酸（所谓的热点）可能贡献大部分相互作用自由能，这一认识带来了鼓励。蛋白质-蛋白质相互作用带来的挑战催生了许多富有创意的方法，包括蛋白质模拟物、订书钉α-螺旋肽和大量受抗体启发的分子设计。在这里，我们回顾了一种更通用的方法：基于片段的药物发现。片段允许更有效地探索新的化学空间领域，但初始命中的亲和力较低。这意味着它们通常不会破坏 PPIs，除非它们被连接，这是 Wells 及其同事开创的方法。基于片段的另一种方法是稳定多蛋白系统未复合的组件在溶液中，并采用传统的基于片段的筛选。在这里，我们描述了蛋白质-蛋白质相互作用的结构和性质以及可以调节它们的小分子的当前知识。然后，我们描述了使用灵敏的生物物理方法（核磁共振、X 射线晶体学、表面等离子体共振、差示扫描荧光法或等温量热法）筛选和验证片段结合。片段命中随后可以进化成具有更高亲和力和效力的更大分子。这些可能为针对蛋白质-蛋白质相互作用并具有治疗价值的候选药物提供新的线索。
