Spectroscopy study on the noncovalent interactions in the binary and ternary systems of l-lysine, adenosine 5′-triphosphate and magnesium ions

Intermolecular interactions of adenosine 5′-triphosphate (ATP) with Lysine (Lys) and Mg2+ were studied in aqueous solution by 1H and 31P NMR spectra. In the metal-free system, the N-1 atom of the purine ring of ATP and carboxyl group of Lys are the interaction sites at low pH conditions. With increasing pH, the interaction efficiency between the phosphate group of ATP and the protonated ammonium group of Lys increased significantly, while that with carboxyl group in Lys decreased. In the Mg2+–Lys–ATP system, multi-interactions, such as coordination, cations (Mg2+, NH3+)–π, hydrogen bonding, ion-pairing interactions and electrostatic interactions co-existed. In addition, the recognition of ATP by the amino acid cation (Lys) was significantly promoted by the addition of magnesium ion, which led to the coordination competition between Lys and ATP.

Graphical abstractIn the metal-free system, the N-1 atom of the purine ring of ATP and carboxyl group of Lys are the interaction sites at low pH conditions. In the Mg2+–Lys–ATP system, multi-interactions, such as coordination, cations (Mg2+, NH3+)–π, hydrogen bonding, ion-pairing interactions and electrostatic interactions co-existed. The recognition of ATP by the amino acid cation (Lys) was significantly promoted by the addition of magnesium ion, which led to the coordination competition between Lys and ATP.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ The N-1 site and the carboxyl group are the interaction sites at low pH, while the interaction centers are the phosphate groups, the N-7 site and the ammonium groups with increasing pH in the ATP-Lys system. ▶ Mg2+ dose not interact directly with the adenine ring of ATP and not recognize α-P, but interacts with β- and γ-P of ATP in the Mg2+-ATP system. ▶ Multiple intermolecular interactions exist in the Lys-ATP-Mg2+ system. ▶ The coordinate competition exists between ATP and Lys, and Mg2+ promotes the interactions between ATP and Lys in the Lys-ATP-Mg2+ system.