Lanthanide ions were used as NMR probes to study the conformation distributions of 5'-CMP, 5'-AMP, and 5'-IMP in acidic aqueous solns. The experimental data of pseudo-contact shift together with the data of spin-lattice relaxation rate as well as spin-coupling constants of 1H spectra were processed by computer. The results show that in aqueous solns. 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 anti-forms.

Key words: CYTIDINE, AQUEOUS SOLUTION, MOLECULAR STRUCTURE, COMPUTER APPLICATIONS, NMR SPECTROMETRY, LANTHANON, PROTON MAGNETIC RESONANCE SPECTROMETRY, COUPLING CONSTANT, PROBES, ADENINE