NMR Observation of Intermolecular Hydrogen Bonds between Protein Tyrosine Side-Chain OH and DNA Phosphate Groups.

Hydrogen bonds between protein side-chain hydroxyl (OH) and phosphate groups are one of the most common types of intermolecular hydrogen bonds in protein-DNA/RNA complexes. Using NMR spectroscopy, we identified and characterized the hydrogen bonds between tyrosine side-chain OH and DNA phosphate groups in a protein-DNA complex. These OH groups exhibited relatively slow hydrogen-exchange rates and sizable scalar couplings between hydroxyl 1H and DNA phosphate 31P nuclei across the hydrogen bonds. Information about intermolecular hydrogen bonds facilitates investigations of the DNA/RNA recognition by the protein.