Probing the Role of Water in Liquid-Liquid Phase Separation Using X-ray Photon Correlation Spectroscopy

Liquid-liquid phase separation (LLPS) is a spontaneous segregation of molecules into distinct liquid phases, creating functional environments that regulate biochemical reactions. LLPS involves protein-protein and protein-water interactions, with water playing a crucial but often underexplored role. Kosmotropic and chaotropic agents, such as Hofmeister series salts, can alter water structuring and protein dynamics, impacting LLPS. However, their specific effects on LLPS dynamics are unclear due to difficulties in probing water's role. X-ray Photon Correlation Spectroscopy (XPCS) offers a unique opportunity to investigate fast and complex dynamics. This proposal aims to utilize XPCS to study LLPS dynamics in protein solutions modulated by kosmotropic and chaotropic agents, to elucidate how changes in water structuring influence the phase behaviour and internal dynamics of the separated phases. This will provide crucial insights into the molecular mechanisms that drive LLPS.

液-液相分离（Liquid-liquid phase separation, LLPS）是指分子自发分离形成不同液相的过程，可构建调控生化反应的功能性微环境。液-液相分离涉及蛋白质-蛋白质与蛋白质-水相互作用，其中水发挥着关键却常被忽视的作用。促溶型与扰溶型试剂（如霍夫迈斯特系列盐）可改变水的结构与蛋白质动力学，进而影响液-液相分离过程。然而，由于难以探测水的作用，这类试剂对液-液相分离动力学的具体影响仍不明确。X射线光子关联谱（X-ray Photon Correlation Spectroscopy, XPCS）为研究快速且复杂的动力学过程提供了独特的手段。本研究计划拟利用X射线光子关联谱，对受促溶型与扰溶型试剂调控的蛋白质溶液中的液-液相分离动力学展开研究，以阐明水结构变化如何影响分离相的相行为与内部动力学过程。该研究将为解析驱动液-液相分离的分子机制提供关键认知。