title: The effects of monovalent cations Li+, Na+, K+, NH4+, Rb+ and Cs+ on the solid and solution structures of the nucleic acid components. Metal ion binding and sugar conformation.
abstract: The interactions of the monovalent ions Li+, Na+, K+, NH4+, Rb+ and Cs+ with adenosine-5'-monophosphoric acid (H2-AMP), guanosine-5'-monophosphoric acid (H2-GMP) and deoxyguanosine-5'-monophosphoric acid (H2-dGMP) were investigated in aqueous solution at physiological pH. The crystalline salts M2-nucleotide.nH2O, where M = Li+, Na+, K+ NH4+, Rb+ and Cs+, nucleotide = AMP, GMP and dGMP anions and n = 2-4 were isolated and characterized by Fourier Transform infrared (FTIR) and 1H-NMR spectroscopy. Spectroscopic evidence showed that these ions are in the form of M(H2O)n+ with no direct metal-nucleotide interaction, in aqueous solution. In the solid state, Li+ ions bind to the base N-7 site and the phosphate group (inner-sphere), while the NH4+ cations are in the vicinity of the N-7 position and the phosphate group, through hydrogen bonding systems. The Na-nucleotides and K-nucleotides are structurally similar. The Na+ ions bind to the phosphate group of the AMP through metal hydration shell (outer-sphere), whereas in the Na2-GMP, the hydrated metal ions bind to the base N-7 or the ribose hydroxyl groups (inner-sphere). The Na2-dGMP contains hydrated metal-carbonyl and metal-phosphate bindings (inner-sphere). The Rb+ and Cs+ ions are directly bonded to the phosphate groups and indirectly to the base moieties (via H2O). The ribose moiety shows C2'-endo/anti conformation for the free AMP acid and its alkali metal ion salts. In the free GMP acid, the ribose ring exhibits C3'-endo/anti conformer, while a C2'-endo/anti sugar pucker was found in the Na2-GMP and K2-GMP salts and a C3'-endo/anti conformation for the Li+, NH4+, Rb+ and Cs+ salts. The deoxyribose has C3'-endo/anti conformation in the free dGMP acid and O4'-endo/anti in the Na2-dGMP, K2-dGMP and a C3'-endo/anti for the Li+, NH4+, Rb+ and Cs+ salts. An equilibrium mixture of the C2'-endo/anti and C3'-endo/anti sugar puckers was found for these metal-nucleotide salts in aqueous solution.
authors.affiliation: Centre de Recherche en Photobiophysique, Université du Québec à Trois-Riviéres, Canada.
authors.forename: H A
authors.initials: HA
authors.lastname: Tajmir-Riahi
authors.forename: S
authors.initials: S
authors.lastname: Messaoudi
mesh_terms: D000249:Adenosine Monophosphate / Q000737:chemistry*; D002414:Cations, Monovalent / Q000737:chemistry*; D002586:Cesium / Q000737:chemistry; D003848:Deoxyguanine Nucleotides / Q000737:chemistry*; D005583:Fourier Analysis; D006157:Guanosine Monophosphate / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008094:Lithium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011188:Potassium / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012413:Rubidium / Q000737:chemistry; D012964:Sodium / Q000737:chemistry
chemical_list: D002414:Cations, Monovalent; D003848:Deoxyguanine Nucleotides; D000644:Quaternary Ammonium Compounds; D002586:Cesium; D000249:Adenosine Monophosphate; C007257:2'-deoxyguanosine 5'-phosphate; D006157:Guanosine Monophosphate; D008094:Lithium; D012964:Sodium; D012413:Rubidium; D011188:Potassium