Abstract Protein crystal nucleation is a central problem in biological crystallography and other areas of science, technology, and medicine. Recent studies have demonstrated that protein crystal nuclei form within crucial precursors. Data for several proteins provided by these methods have demonstrated that the nucleation precursors are clusters consisting of protein dense liquid, which are metastable with respect to the host protein solution. The clusters are several hundred nanometers in size, they occupy from 10 −7 to 10 −3 of the solution volume, and their properties in solutions supersaturated with respect to crystals are similar to those in homogeneous, i.e., undersaturated, solutions. The clusters exist due to the conformation flexibility of the protein molecules, leading to the exposure of hydrophobic surfaces and enhanced intermolecular binding. These results indicate that protein conformational flexibility might be the mechanism behind the metastable mesoscopic clusters and crystal nucleation. The investigations of the cluster properties are still in their infancy. Results on direct imaging of cluster behaviors and characterization of cluster mechanisms with a variety of proteins will soon lead to major breakthroughs in protein biophysics.

中文翻译：

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蛋白质晶体的成核

摘要 蛋白质晶体成核是生物晶体学和其他科学、技术和医学领域的核心问题。最近的研究表明，蛋白质晶核在关键前体中形成。这些方法提供的几种蛋白质的数据表明，成核前体是由蛋白质致密液体组成的簇，相对于宿主蛋白质溶液是亚稳态的。簇的大小为数百纳米，它们占据溶液体积的10 -7 至10 -3 ，并且它们在相对于晶体过饱和的溶液中的性质类似于在均质即欠饱和溶液中的性质。簇的存在是由于蛋白质分子的构象灵活性，导致疏水表面暴露并增强分子间结合。这些结果表明蛋白质构象灵活性可能是亚稳态介观簇和晶体成核背后的机制。对集群属性的研究仍处于起步阶段。对各种蛋白质的簇行为直接成像和对簇机制进行表征的结果将很快导致蛋白质生物物理学的重大突破。