Download Mendeley(205)Tl NMR methods for the characterization of monovalent cation binding to nucleic acids
Gill, M.L., Strobel, S.A., Loria, J.P.(2005) J Am Chem Soc 127: 16723-16732
- PubMed: 16305263
- DOI: https://doi.org/10.1021/ja055358f
- Primary Citation of Related Structures:
2AKG - PubMed Abstract:
Monovalent cations play an important role in many biological functions. The guanine rich sequence, d(G4T4G4), requires monovalent cations for formation of the G-quadruplex, d(G4T4G4)2. This requirement can be satisfied by thallium (Tl+), a potassium (K+) surrogate. To verify that the structure of d(G4T4G4)2 in the presence of Tl+ is similar to the K+-form of the G-quadruplex, the solution structure of the Tl+-form of d(G4T4G4)2 was determined. The 10 lowest energy structures have an all atom RMSD of 0.76 +/- 0.16 A. Comparison of this structure to the identical G-quadruplex formed in the presence of K+ validates the isomorphous nature of Tl+ and K+. Using a 1H-205Tl spin-echo difference experiment we show that, in the Tl+-form of d(G4T4G4)2, small scalar couplings (<1 Hz) exist between 205Tl and protons in the G-quadruplex. These data comprise the first 1H-205Tl scalar couplings observed in a biological system and have the potential to provide important constraints for structure determination. These experiments can be applied to any system in which the substituted Tl+ cations are in slow exchange with the bulk ions in solution.
Organizational Affiliation:
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA.
