Fig. 1: Descriptors of collective interactions in biomolecular phase separation.
From: Quantifying collective interactions in biomolecular phase separation
a Schematic of a full phase diagram for a 2-D system between components A and B (abbreviated as Comp.). The coexistence region is shaded in blue. Tie lines describe the demixing of a total composition (ctot) within the coexistence region into dilute (cdil) and dense phase concentrations (cden). The tie line gradient K is informative of component partitioning and can be obtained by determining conditions of \({c}_{{\mbox{dil}}}^{{\mbox{A}}}\) = const. b In higher-dimensional systems, tie lines do not have to be constrained to the A-B measurement plane (blue). Enforcing the condition \({c}_{{\mbox{dil}}}^{{\mbox{A}}}\) = const., reduces the higher-dimensional tie lines to the A-B measurement plane, resulting in a so-called dilute phase contour. Dilute phase contours correspond to the intersection of the higher-dimensional tie lines originating from the B-C plane at \({c}_{{\mbox{dil}}}^{{\mbox{A}}}\) = const (purple), with the A-B measurement plane of interest. c Reduction of tie lines to the A-B measurement plane gives rise to information on K. Furthermore, the local dependence of the saturation concentration on both component A and B is described by the phase boundary gradient P. d Together K and P inform on the relative free energy decrease for phase separation of component A as given by the dominance of component A (DA). Both K and P can be determined from measurements of \({c}_{{\mbox{dil}}}^{{\mbox{A}}}\) only.
