Over the past decade, the structural biology of membrane proteins (MPs) has taken a new turn thanks to epoch-making technical progress in single-particle electron cryo-microscopy (cryo-EM) as well as to improvements in sample preparation. The present analysis provides an overview of the extent and modes of usage of the various types of surfactants for cryo-EM studies. Digitonin, dodecylmaltoside, protein-based nanodiscs, lauryl maltoside-neopentyl glycol, glyco-diosgenin, and amphipols (APols) are the most popular surfactants at the vitrification step. Surfactant exchange is frequently used between MP purification and grid preparation, requiring extensive optimization each time the study of a new MP is undertaken. The variety of both the surfactants and experimental approaches used over the past few years bears witness to the need to continue developing innovative surfactants and optimizing conditions for sample preparation. The possibilities offered by novel APols for EM applications are discussed.

中文翻译：

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通过单粒子电子冷冻显微镜确定膜蛋白结构的两亲环境

在过去的十年中，由于单粒子电子冷冻显微镜 (cryo-EM) 的划时代技术进步以及样品制备的改进，膜蛋白 (MPs) 的结构生物学发生了新的变化。本分析概述了用于冷冻电镜研究的各种类型表面活性剂的使用范围和模式。洋地黄皂苷、十二烷基麦芽糖苷、蛋白质基纳米圆盘、月桂基麦芽糖苷-新戊二醇、糖-薯蓣皂苷元和两性酚 (APols) 是玻璃化步骤中最常用的表面活性剂。MP 纯化和网格制备之间经常使用表面活性剂交换，每次研究新的 MP 时都需要进行广泛的优化。过去几年使用的表面活性剂和实验方法的多样性证明了继续开发创新的表面活性剂和优化样品制备条件的必要性。讨论了新型 APol 为 EM 应用提供的可能性。