PT  - JOURNAL ARTICLE
AU  - Jasper J. Michels
AU  - Mateusz Brzezinski
AU  - Tom Scheidt
AU  - Edward A. Lemke
AU  - Sapun Parekh
TI  - Role of Solvent Compatibility in the Phase Behavior of Binary Solutions of Weakly Associating Multivalent Polymers
AID  - 10.1101/2021.09.09.459431
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.09.09.459431
4099  - http://biorxiv.org/content/early/2021/09/10/2021.09.09.459431.short
4100  - http://biorxiv.org/content/early/2021/09/10/2021.09.09.459431.full
AB  - Condensate formation of biopolymer solutions, prominently those of various intrinsically disordered proteins (IDPs), is determined by 'sticky' interactions between associating residues, multivalently present along the polymer backbone. Using a ternary mean field 'stickers-and-spacers' model, we demonstrate that if sticker association is of the order of a few times the thermal energy, a delicate balance between specific binding and non-specific polymer-solvent interactions gives rise to a particularly rich ternary phase behavior under physiological circumstances. For a generic system represented by a solution comprising multi-associative scaffold and client polymers, the difference in solvent compatibility between the polymers modulates the nature of isothermal liquid-liquid phase separation (LLPS) between associative and segregative. The calculations reveal regimes of dualistic phase behavior, where both types of LLPS occur within the same phase diagram, either associated with the presence of multiple miscibility gaps, or a flip in the slope of the tie-lines belonging to a single coexistence region.Competing Interest StatementThe authors have declared no competing interest.