APPLICATION OF LANTHANIDE IONS AS PROBES OF NUCLEAR-MAGNETIC-RESONANCE TO STUDIES OF MOLECULAR-CONFORMATIONS - CONFORMATIONAL-ANALYSES OF 3 NUCLEOTIDES IN AQUEOUS-SOLUTIONS

Lanthanide ions were used as NMR probes to study the conformation distributions of cytidine (5'-CMP), adenosine (5'-AMP), and inosine (5'-IMP) in acidic aqueous solutions. The experimental data of pseudo-contact shift together with the data of spin-lattice relaxation rate as well as spin-coupling constants of H-1 spectra were processed by computer. The results show that in aqueous solutions the conformations of the nucleotides exist in equilibrium as a group of conformers. In comparison with crystalline state, the dihedral angles around single bonds and the puckering forms of ribose ring have changed to some extent. However, the base groups are still in antiforms.