Non-equilibrium phase separation in mixtures of catalytically active particles: size dispersity and screening effects

Abstract

Biomolecular condensates in cells are often rich in catalytically-active enzymes. This is particularly true in the case of the large enzymatic complexes known as metabolons, which contain different enzymes that participate in the same catalytic pathway. One possible explanation for this self-organization is the combination of the catalytic activity of the enzymes and a chemotactic response to gradients of their substrate, which leads to a substrate-mediated effective interaction between enzymes. These interactions constitute a purely non-equilibrium effect and show exotic features such as non-reciprocity. Here, we analytically study a model describing the phase separation of a mixture of such catalytically-active particles. We show that a Michaelis-Menten-like dependence of the particles' activities manifests itself as a screening of the interactions, and that a mixture of two differently-sized active species can exhibit phase separation with transient oscillations. We also derive a rich stability phase diagram for a mixture of two species with both concentration-dependent activity and size dispersity. This work highlights the variety of possible phase separation behaviours in mixtures of chemically-active particles, which provides an alternative pathway to the passive interactions more commonly associated with phase separation in cells. Our results highlight non-equilibrium organizing principles that can be important for biologically relevant liquid-liquid phase separation.

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• Non-equilibrium phase separation in mixtures of catalytically active particles: size dispersity and screening effects
• Nonequilibrium Transport Induced by Biological Nanomachines
• Network effects lead to self-organization in metabolic cycles of self-repelling catalysts
• Interaction-motif-based classification of self-organizing metabolic cycles
• Collective synchronization of dissipatively-coupled noise-activated processes
• Active Phases for Particles on Resource Landscapes
• Continuous-time multifarious systems -- Part II: non-reciprocal multifarious self-organization
• Non-reciprocal interactions between condensates in chemically active mixtures