Protein-Ligand Interaction Analyses with Nuclear Magnetic Resonance Spectroscopy Enhanced by Dissolution Triplet Dynamic Nuclear Polarization

Solution-state nuclear magnetic resonance spectroscopy(NMR) isa powerful method for the analysis of intermolecular interactionswithin a biomolecular system. However, low sensitivity is one of themajor obstacles of NMR. We improved the sensitivity of solution-state C-13 NMR for the observation of intermolecular interactionsbetween protein and ligand using hyperpolarized solution samples atroom temperature. Eutectic crystals composed of C-13-salicylicacid and benzoic acid doped with pentacene were hyperpolarized bydynamic nuclear polarization using photoexcited triplet electrons,and a C-13 nuclear polarization of 0.72 & PLUSMN; 0.07% wasachieved after dissolution. The binding of human serum albumin and C-13-salicylate was observed with several hundred times sensitivityenhancement under mild conditions. The established (CNMR)-C-13 was applied for pharmaceutical NMR experiments by observationof the partial return of the C-13 chemical shift of salicylateby competitive binding with other non-isotope-labeled drugs.