Glycine solvation in supercooled water

Abstract

The study of glycine has recently attracted significant attention in various fields such as astrochemistry and hydrate formation. In the former case, several authors have speculated that glycine, coming from comets, may be at the origin of life on Earth. For hydrates, it is known that their formation is altered by the presence of glycine molecules, solvated in water. The solvation properties of glycine could be responsible for these situations. Here, we address the solvation of glycine in liquid water, using molecular dynamics simulations. Our studies were developed from room temperature down to the supercooled region. A thermodynamic analysis was performed using the Kirkwood–Buff theory and shows that the solution deviates from ideality with a maximum at 15% of glycine. Interestingly, the activity coefficient exhibits a significant decrease with temperature and concentration. A complementary structural analysis with the q̄4 Steinhard parameter and CHILL+ algorithm revealed that the presence of glycine enhances ordering of water, although it prevents the formation of ice.