Water interaction with glycine betaine: A hybrid QM/MM molecular dynamics simulation

Experiments suggest that under conditions of water stress the preservation of functional stereodynamics of biomolecules by so-called 'compatible solutes' is related to their interaction with water. In the present work, the interaction of water with glycine betaine, which is one of the osmoprotectants most effective and widespread in nature, is investigated using quantum mechanical calculations and QM/MM molecular dynamics simulation. Its effects on structure and dynamics of the surrounding water are compared with those exerted by two other remarkable bioprotectants: the disaccharide trehalose and the quaternary ammonium compound TMAO (trimethylamine-N-oxide). In particular, statistical analysis of a 500 ps simulation trajectory evidences common features of the 3D water distributions around glycine betaine and TMAO.