Using light to weigh membrane proteins in lipid bilayers

为了在细胞膜内保持稳定性，膜蛋白具有大的暴露的疏水结构域。这些蛋白质的溶解和纯化，同时保持正确的结构和活性，使这种保守的结构变得复杂。天然或真实的脂质环境尤为重要，因为膜蛋白周围的脂质组成已被证明对其结构和活性有很大影响。膜蛋白是治疗药物靶点的重要组成部分，是药学研究的一个重要领域。进一步发展可靠的活度测量和结构研究技术具有重要意义。最近，脂盘形成共聚物（如苯乙烯马来酸）已成功地用于溶解、纯化和表征各种膜蛋白。苯乙烯马来酸（SMA）在生物膜的存在下形成苯乙烯马来酸脂质颗粒（SMALPs）。这些小颗粒纳米圆盘的形成可以封装存在于这些膜中的膜蛋白，并在蛋白质周围保留天然的脂质环，这意味着SMA比传统的洗涤剂增溶方法具有一些优势。Refeyn最近发展了质谱仪作为一种分析技术来测量溶液中单个分子的质量，而不需要事先进行分子标记。这为天然状态下分子结构和动力学的行为表征开辟了许多研究途径。该项目旨在利用脂盘形成共聚物或传统的洗涤剂方法优化目标膜蛋白的增溶和纯化。在此之后，质谱法将被优化为一种表征和测量这些靶膜蛋白在天然状态下的蛋白质-蛋白质相互作用的技术。这项研究有可能提供膜蛋白相互作用机制的详细特征，并为新的或当前的药物靶点提供见解。

Membrane proteins have large exposed hydrophobic domains for stability within the cell membrane. Solubilisation and purification of these proteins, whilst retaining correct structure and activity, is made complex by this conserved structure. A native or realistic lipid environment is particularly important, as lipid composition surrounding membrane proteins has been shown to greatly affect their structure and activity. Membrane proteins make up a large portion of therapeutic drug targets and are an important area of study for pharmaceutical research. It is of high interest to further develop reliable techniques for measuring activity and investigating structure.Recently, lipid-disc forming copolymers (such as styrene maleic acid) have been used successfully to solubilise, purify and characterise a variety of membrane proteins. Styrene maleic acid (SMA) forms styrene maleic acid lipid particles (SMALPs) in the presence of biological membranes. Formation of these SMALP nano-discs can encapsulate membrane proteins present in these membranes and retain a native annulus of lipid around the protein, meaning SMA provides some advantages over traditional detergent solubilisation methods.Refeyn have recently developed mass photometry as an analytical technique to measure the mass of singular molecules in solution without prior molecule labelling. This opens many pathways of research for the behavioural characterisation of molecule structure and dynamics in a native state.This project aims to optimise the solubilisation and purification of target membrane proteins using lipid-disc forming copolymers or traditional detergent methods. Following this, mass photometry will be optimised as a technique to characterise and measure protein-protein interactions of these target membrane proteins in a native state. This research has the potential to provide a detailed characterisation of membrane protein interaction mechanisms and give insights into new or current drug targets.