SKM 2023 – scientific programme
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BP: Fachverband Biologische Physik
BP 11: Poster Session I
BP 11.56: Poster
Tuesday, March 28, 2023, 12:30–15:30, P1
Theory of rheology and aging of protein condensates — •Ryota Takaki1, Louise Jawerth2, Marko Popovic1, and Frank Jülicher1 — 1Max Planck Institute for the Physics of Complex Systems — 2Leiden University
Biological polymeric materials form liquid droplets through liquid-liquid phase separation, referred to as biological condensates. Although the material properties of biological condensates are deemed to play essential roles in cellular functions, quantitative studies of condensates' rheology became available very recently. Particularly the experiments found the glass-like material property of condensates, showing slow relaxation, termed "aging" in the glass field. In this study, we develop a rheological model of biological condensates from the physical pictures: diffusion and stochastic binding of proteins inside condensates. We obtain the constitutive equation for the material property of protein condensates showing aging behavior observed in experiments. We elucidate how aging manifests in the experimental observations in microrheology, both in active and passive rheology. We develop a novel method for active rheology to compute the time-dependent property of aging materials. We derive generalized fluctuation-response relations to bridge the mean squared displacement of diffusing elements inside aging Maxwell fluid to the time-dependent material properties, which can be used in passive rheology.