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Publication in Nature Chemistry: A Novel Method Revealing Biological Condensate Composition
Biological condensates are small, membraneless organelles typically consisting of multiple proteins and nucleic acids within cells. They are involved in a diverse array of cellular processes but, despite their importance, methods to quantify their molecular makeup are lacking. Now, in a groundbreaking publication, researchers from the Brugués group at the Cluster of Excellence Physics of Life of Dresden University of Technology, the Leibniz Institute of Polymer Research Dresden, and the Max Planck Institute of Molecular Cell Biology and Genetics reveal a new experimental method to measure the molecular makeup of condensates.
Analysis of Tie-lines and Refractive Index (ATRI) is a label-free method to infer the composition of condensates reconstituted from complex mixtures. The key realization behind ATRI is that combining refractive index measurements with the tie-line graphically results in two lines that meet at one specific point: the point representing condensate composition.
“We were able to resolve the concentrations of five distinct molecules in the same condensate, revealing how the local composition can control physical properties like density and solvent content in a more realistic reconstitution”, says Dr. Patrick McCall, independent research associate at IPF and lead author of the study. At the time of publication, experiments capable of resolving more than two proteins in a condensate without using fluorescence have not been reported previously, highlighting the significance of this new method.
By revealing the composition of condensates quantitatively, ATRI opens the door to predicting their behavior more accurately and studying how subtle changes in composition affect their biological function. Beyond basic science, the new method has the potential to drive biomedical advances as well. Condensates play a role in numerous disorders and, by exposing how a condensate’s molecular makeup responds to promising compounds, ATRI may aid the development of potent therapeutics and treatments in future.
03.09.2025