Nestorow Stephanie A, Dafforn Tim R, Frasca Verna
University of Birmingham, Birmingham, U.K.
Malvern Panalytical, 22 Industrial Drive East, Northampton, Massachusetts 01060, U.S.A.
Biochem Soc Trans. 2021 Nov 1;49(5):2037-2050. doi: 10.1042/BST20201088.
Membrane proteins such as receptors, ion channels and transport proteins are important drug targets. The structure-based study of membrane proteins is challenging, especially when the target protein contains both soluble and insoluble domains. Most membrane proteins are insoluble in aqueous solvent and embedded in the plasma membrane lipid bilayer, which significantly complicates biophysical studies. Poly(styrene-co-maleic acid) (SMA) and other polymer derivatives are increasingly common solubilisation agents, used to isolate membrane proteins stabilised in their native lipid environment in the total absence of detergent. Since the initial report of SMA-mediated solubilisation, and the formation of SMA lipid particles (SMALPs), this technique can directly isolate therapeutic targets from biological membranes, including G-protein coupled receptors (GPCRs). SMA now allows biophysical and structural analyses of membrane proteins in solution that was not previously possible. Here, we critically review several existing biophysical techniques compatible with SMALPs, with a focus on hydrodynamic analysis, microcalorimetric analysis and optical spectroscopic techniques.
诸如受体、离子通道和转运蛋白等膜蛋白是重要的药物靶点。基于结构对膜蛋白进行研究具有挑战性，尤其是当目标蛋白同时包含可溶性和不溶性结构域时。大多数膜蛋白不溶于水性溶剂，而是嵌入质膜脂质双层中，这使得生物物理研究显著复杂化。聚（苯乙烯 - 马来酸）（SMA）及其他聚合物衍生物是越来越常用的增溶剂，用于在完全不存在去污剂的情况下分离稳定于其天然脂质环境中的膜蛋白。自从首次报道SMA介导的增溶作用以及SMA脂质颗粒（SMALPs）的形成以来，该技术能够直接从生物膜中分离治疗靶点，包括G蛋白偶联受体（GPCRs）。SMA现在使得对溶液中的膜蛋白进行生物物理和结构分析成为可能，而这在以前是无法实现的。在此，我们批判性地综述了几种与SMALPs兼容的现有生物物理技术，重点关注流体动力学分析、微量量热分析和光谱技术。
