Anisotropic Interactions in Protein Mixtures: Self Assembly and Phase Behavior in Aqueous Solution.
Recent experimental studies show that oppositely charged proteins can self-assemble to form seemingly stable microspheres in aqueous salt solutions. We here use parallel tempering Monte Carlo simulations to study protein phase separation of lysozyme/α-lactalbumin mixtures and show that anisotropic electrostatic interactions are important for driving protein self-assembly. In both dilute and concentrated protein phases, the proteins strongly align according to their charge distribution. While this alignment can be greatly diminished by a single point mutation, phase separation is completely suppressed when neglecting electrostatic anisotropy. The results highlight the importance of subtle electrostatic interactions even in crowded biomolecular environments where other short-ranged forces are often thought to dominate.
Department of Theoretical Chemistry, Lund University, POB 124 SE-22100 Lund, Sweden.
Anıl
A
Kurut
Department of Theoretical Chemistry, Lund University, POB 124 SE-22100 Lund, Sweden.
Björn A
BA
Persson
Department of Theoretical Chemistry, Lund University, POB 124 SE-22100 Lund, Sweden.
Torbjörn
T
Åkesson
Department of Theoretical Chemistry, Lund University, POB 124 SE-22100 Lund, Sweden.
Jan
J
Forsman
Department of Theoretical Chemistry, Lund University, POB 124 SE-22100 Lund, Sweden.
Mikael
M
Lund
coarse graining; electrostatics; microsphere formation; noncentrosymmetric interactions; protein−protein interactions; whey proteins