Biomolecular condenstates refer to the membraneless organelles formeed through spontaneous association and concentration of proteins and nucleic acids. Due to this specific organization, these condenstates can be programmed to carry out diverse processes, such as RNA metabolism, DNA repair, and signal transduction. Recent studies have shown that liquid-liquid phase separation driven by multivalent macromolecular interactions is the reason for their formation and physical properties.
Properties of these condensates can be studies using the principles of polymer chemistry and soft matter physics—mainly the assembly, dissolution, composition, and function.
The presence of a phase boundary can explain how molecules can be concentrated in one place but also undergo biochemical reactions that require rapid diffusion.
Multivalency driven phase separation
In the cell, the presence of separate phases enables the maintenance of chemical equilibrium between the components of different chemical properties through the rapid movement of molecules in between them. These condensates often contain an abundance of multivalent molecules—molecules with a multitude of entities that govern the intra- and inter- molecular interactions. From classical polymer chemistry, such multivalent molecules assemble into large oligomers or polymers. This assembly inherently decreases the solubility of the molecules due to entropy-driven effects leading to phase separation.
So what I understand is that there are two factors: 1) the strength of macromolecule-water interaction, and the 2) affinity of the macromolecules. The phase separation occurs when the affinity of the macromolecules is stronger than the macromolecule-water interaction usually obtained by the increase of concentration of the solute. Also, this phase separation creates a phase boundary that allows the molecules to be concentrated in one place and undergo swift reactions. They can also exchange molecules with surrounding environment, which is important for the biochemical reactions that require rapid diffusion.