Kaarthik Varma, Cornell University

Critical Phenomena in Biomolecular Condensates: Structure and Dynamics

The study of biomolecular condensates in a cell has become increasingly important due to its implications in health physiology and disease. Phase separation has become a popular framework to study them. Any system which shows phase separation can be characterized by an underlying phase diagram, with tie lines. What implications does location on the phase diagram have on the properties of the biomolecular condensates? To address this question, we focus on a fascinating point on the phase diagram – the critical point and seek to enumerate all the interesting effects related to proximity to the critical point. We start with a very simple model system for biomolecular condensates – mixture of protein (BSA) in polymer (PEG) whose phase diagram is well known to us. We measure the supramolecular structure and material properties of the protein mixtures near the critical point. We compare to scaling theories and discuss implications for the  dynamics of condensates.