Site-Resolved Measurement of Water-Protein Interactions by Solution NMR

The interactions of biological macromolecules with water are fundamental to their structure, dynamics and function. Historically, characterization of the location and residence times of hydration waters of proteins in solution has been quite difficult. Confinement within the nanoscale interior of a reverse micelle slows water dynamics, allowing detection of global protein-water interactions using nuclear magnetic resonance techniques. Complications that normally arise from hydrogen exchange and long-range dipolar coupling are overcome by the nature of the reverse micelle medium. Characterization of the hydration of ubiquitin demonstrates that encapsulation within a reverse micelle allows detection of dozens of hydration waters. Comparison of nuclear Overhauser effects obtained in the laboratory and rotating frames indicate a considerable range of hydration water dynamics is present on the protein surface. In addition, an unprecedented clustering of different hydration dynamic classes of sites is evident.