Field-theoretic simulations of discrete Gaussian chain polyelectrolytes as a model for coacervation in intrinsically disordered peptides.*

Recent experimental observations of coacervation in intrinsically disordered peptides (IDPs) have raised intriguing questions about their role in IDP aggregation and fibrilization. At the theoretical level such systems are challenging due to the heterogeneous but highly specific sequence of amino acids which constitute IDPs as well as by the subtle but important short-ranged interactions between amino acids in an aqueous solvent. Additionally, phosphorylation, pH, and specific mutations can alter the distribution of charged residues and thereby affect the propensity for coacervation. Here we present field-theoretic simulations of the fully fluctuating Hamiltonian for polymers modeled as discrete Gaussian chains with specific charged residues. Such simulations represent an approximation-free attempt to show how the phase diagram depends on the sequence of charges along the protein backbone, the presence of salts, and the polymer excluded volume. We also compare with coarse-grained molecular dynamics simulations and discuss the relevance for understanding experiments of real proteins.