Dynamic Nuclear Polarization to Map Hydrogen in Biological Crystals

Chemical reactions or biological transformations often occur through charge-transfer, bond-dissociation, protonation or de-protonation. Therefore, precious information about hydrogen positions is crucial to understand the biological process or drug design. However, conventional X-ray crystallography provides insight only into heavy atom positions and only offers limited information using very high resolution.

In this regard, neutron macromolecular crystallography (NMC) is the structural biological method of choice that provides isotope-specific information from scattering by hydrogen or deuterium nuclei.

Here, we investigate the emerging method of dynamic nuclear polarization (DNP)-NMC which uses alignment between incident neutron and proton nuclear spins.

In this theoretical analysis, we implement a method that reconstructs phases of polarized hydrogen diffraction with over 80$\%$ accuracy from simulation, only using protonated states or backbone hydrogens as phasing hints. The method is able to, theoretically, achieve full reconstruction accuracy and provides the foundation for the novel IMAGINE-X instrument design at ORNL.