Mihir Upadhye

USING OVENHAUSER DYNAMIC NUCLEAR POLARIZATION TO STUDY HYDRATION SHELL WATER DYNAMICS

Mihir Upadhye, Thomas Webber, Candice Crilly, Songi Han

The hydration shell which closely surrounds a macromolecule in aqueous solution is known to encode information about the molecule’s surface. Thus, the Hydration shell is the first point of contact between molecules and their surrounding environment. For proteins, he hydration shell gives us important information about folding, aggregation, and stability. While detailed mapping of the hydration hell through simulations has been possible since the early 2000s, direct measurement of spatially resolved hydration properties in aqueous solutions has proven difficult. The Han Lab has developed a combined nuclear magnetic resonance (NMR) and electron magnetic resonance (EPR) technique to study site specific hydration dynamics so we can experimentally determine the motion of water This technique, known as Overhauser dynamic nuclear polarization (ODNP) polarizes both electron and proton spins, and use their relaxation time to determine the speed of water (nm/ps). We apply ODNP to various spin-labeled sites along the chemically heterogeneous protein Chemotaxis Y (CheY). We hypothesize that water near hydrophilic patches will slow down more, due to the attraction between Hydration water and the protein’s surface. By relating ODNP measurements to molecular dynamics (MD) simulations, we study the protein’s behavior in further detail and make predictions of protein stability and aggregation based on thermodynamic favorability. This allows us to predict protein interaction, oligomerization, folding, and aggregation, making ODNP’s relevance to biological systems and human health a vital tool.