Neutron Crystallographic Studies of Amino Acids and Nucleic Acids

Abstract

Neutron crystallographic studies of two representative umami materials were executed utilizing iBIX at MLF/J-PARC. The results of them will be summarized in this report. At first, structure analysis of the alpha form crystal of L-glutamic acid was performed in order to assess the usefulness of neutron crystallography at iBIX to our company’s R&D. Neutron crystal structure of it was successfully determined at 0.6 Å resolution. All hydrogen atoms were clearly observed. Next, the mixed crystal of disodium Inosine-5’-phosphate (IMP・2Na) and disodium Guanosine-5’-phosphate (GMP・2Na) was analyzed by neutron crystallography. Neutron crystal structure of the mixed crystal of IMP and GMP (IMP/GMP rate = 1.7) was successfully determined at 0.8 Å resolution. In the neutron crystal structure of the mixed crystal, the hydrogen atom bonded to the C2 atom of purine base in IMP and the nitrogen atom bonded to the C2 atom of purine base in GMP were clearly observed in the nuclear density map, structurally demonstrating that this crystal is the mixed crystal.