Short- and long-range crowding effects on water’s hydrogen bond networks
Xiao You, Joseph C. Shirley, Euihyun Lee, Carlos R. Baiz
Abstract
Intracellular water is highly confined with approximately 40% of the cell volume occupied by biomolecules. Crowding alters water dynamics and interactions with biomolecules. In biochemical experiments, artificial crowders are commonly used to mimic intracellular environments, but their effects on biomolecules remain elusive. Here, we investigate the crowding effects by directly accessing the picosecond hydrogen-bond dynamics in crowded solutions using ultrafast two-dimensional infrared spectroscopy and all-atom molecular dynamics simulations. We quantify the effects of different crowding agents: small sugars; polysaccharides; and polyethylene glycol (PEG). Our results show that crowders introduce disorder within the first two solvation shells but stabilize ice-like order in water >1 nm from the crowder. The results show that accounting for crowder chemical structure, conformation, and crowder-solvent interactions is a key step toward a complete description of crowded solutions for in vitro for biomolecular studies.