UC Santa Barbara

Hydration water is necessary for protein function. It was long thought that the hydration water was simply an innocent solvent. However, current findings show that water is not an innocent solvent but an active player. It is now thought that hydration water plays a crucial role in biomolecular recognition by mediating the thermodynamic interaction between a protein and its ligand. The current challenge is to measure the hydration water and protein side chain thermodynamical properties.

In this thesis we present site-specific measurements of hydration water motion on an array of biomolecular surfaces. We rationalize the hydration water motion in terms of the biomolecular surface properties. We find that the hydration water surrounding globular proteins contains information about the chemical and geometrical topology of the protein surface. We then present instrumentation developments to the Overhauser dynamic nuclear polarization (ODNP) methodology that made such measurements possible.

We then introduce a new technique to measure the protein dynamic transition site- specifically and thus a new way to probe the coupling between a protein and the sur- rounding hydration water. We present measurements made on a small folded peptide system, the Trp Cage, and find that the hydration water motion and the protein dy- namic transition temperature are homogeneous across the surface of the peptide.

Finally we discuss the development of a high field pulse EPR spectrometer that features arbitrary waveform generation capabilities. We showcase the applicability of this instrument and discuss the applicability of this instrument to the study of protein structure and dynamics.