Much of the detail regarding the causes of pressure-induced unfolding has been revealed from molecular dynamics simulations. However, these simulations have focused mainly on the hydrophobic effect and the hydration of aliphatic residues, and not on aromatic pi-pi interactions. However, a recent simulation shows that aromatic pairs respond differently to an increase in urea concentration, which is not unlike an increase in pressure, compared to aliphatic pairs. It is the aim of the present research proposal to investigate the effect of high hydrostatic pressure on the hydration properties of phenylalanine, one of the few amino acids with an aromatic group in its side chain. It is expected that these experiments will provide us with new information regarding the contribution of pi-pi interactions to protein stability at high pressures and mechanistic insight herein.