Ordering effect of protein surfaces on water dynamics: NMR relaxation study

Proteins in solution affect the structural and dynamic properties of the bulk water at the protein-water interface, resulting in a contribution to the order of the hydration water. Theoretical and experimental NMR relaxation methods were developed to study the dynamic properties of water molecules in the protein hydration shell. Water non-selective and selective relaxation rates, were shown to be sensitive to contributions from ordered solvent molecules at protein surface. The average rotational correlation time of water molecules in the protein hydration shell was determined for three protein systems of different size: ribonuclease A, human serum albumin and fibrinogen. The knowledge of these properties is an important step toward the determination of the size of the water ordering contributions originate in proteins systems.