Invited
Osmolytes as modulators of lipid and macromolecular interactions

Solution composition is known to strongly influence the stable state of macromolecules, with important practical applications ranging from colloidal dispersions to solvated polymers or proteins. To counteract environmental stress, many organisms regulate the amounts of molecularly small solutes termed osmolytes, which have different affinities to specific macromolecular states and can shift equilibrium towards the thermodynamically preferred state with lower free energy. Solutes preferentially excluded from macromolecules drive depletion forces and stabilize the compact macromolecular state. To contrast, cosolutes preferentially included around the macromolecule usually destabilize the compact state, effectively stabilizing the extended state of the macromolecule, as in the case of protein denaturants. This talk will address the effect of osmolytes on lipid interactions, explaining how osmolytes can increase membrane–membrane attraction or repulsion depending on their preferential interactions with lipids.