Nuclear magnetic resonance spectroscopy as a tool to probe molecular condensates.

Biomolecular condensates formed via liquid-liquid phase separation regulate essential cellular processes, with dysregulation implicated in neurodegeneration and cancer. Nuclear magnetic resonance (NMR) spectroscopy provides label-free, atomic-resolution insights into condensate composition, stoichiometry, physicochemical properties (e.g., viscosity and water content), and molecular interactions, overcoming the limitations of imaging and bulk techniques. This review highlights NMR's capabilities in quantifying selective partitioning of proteins, RNAs, ions, and small molecules, as well as mapping interaction hotspots in scaffold proteins, and characterizing client molecule dynamics within condensates. Finally, we point to future applications, including the study of the modulation of the protein conformational landscape by condensates, drug development targeting pathological phase transitions, and integration with advanced techniques like dynamic nuclear polarization, single-molecule microscopy, and advanced computational models for studying complex physiological systems.