Hydrogen bond dynamics in intrinsically disordered proteins.

Hydrogen bond dynamics is used to investigate the internal motions and structural plasticity of intrinsically disordered (ID) proteins. Group a represent completely disordered proteins, while group b proteins are comprised of regular secondary structures linked by flexible disordered regions. Molecular dynamics simulations of two different groups of ID proteins provide an insight into the hydrogen bond dynamics via the evaluation of the continuous and intermittent time autocorrelation functions. The intermolecular hydrogen bonds between the residues of the ID proteins and water record a short lifetime in both groups of proteins. The intermolecular hydrogen bonds relax faster at a constant rate compared to that of the intramolecular hydrogen bonds whose rate of decay fluctuate during the entire simulation trajectory. The simulations reveal that the intramolecular hydrogen bonds have a longer lifetime in group b proteins compared to those in group a proteins. The hydrophilic residues in ID proteins form stable persistent intramolecular hydrogen bonds as compared to the hydrophobic residues and help to maintain the dynamic equilibrium among the interconvertible conformations.