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 solut es' is related to their interaction with water. In the present work, the in teraction of water with glycine betaine, which is one of the osmoprotectant s most effective and widespread in nature, is investigated using quantum me chanical 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 part icular, statistical analysis of a 500 ps simulation trajectory evidences co mmon features of the 3D water distributions around glycine betaine and TMAO .