The influence of Li+, Na+, Mg2+, Ca2+, and Zn2+ ions on the hydrogen bonds of the Watson–Crick base pairs

✍ Scribed by Eugen H. S. Anwander; Michael M. Probst; Bernd M. Rode

• Publisher: Wiley (John Wiley & Sons)
• Year: 1990
• Tongue: English
• Weight: 927 KB
• Volume: 29
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360290410

✦ Synopsis

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SY NOPSlS

T h e interaction of mono-and divalent metal ions with the nucleic acid base pairs A:T and G:C has been studied using a b initio self-consistent field Hartree-Fock computations with minimal basis sets. Energy-optimi:ed structures of the two base pairs with a final base-base distance of L = 10.35 A have been determined and were further used in calculations on ternary complexes M"+ -A:H together with previously computed coordination geometries of the cations at adenine (Ade), thymine (Thy), and guanine (Gua). Besides the binding energy of the various metal ions t o t h e base pairs, changes in the stability of the H bonds between Ade and T h y or Gua and Cyt have been determined. Polarization effects of the metal ion on the ligand turned out t o increase the binding between complementary bases. Regardless of the metal species, cation binding t o Gua N(3) and Thy O(2) leads t o a special increase in H-bond stability, whereas binding t o Ade N(3) changes the H-bond stability least. Situated in between are the stabilizing effects caused by Gua and Ade N(7) coordination. A remarkable relation between the stability of the H bond and the distance from metal binding site t o H bonds was found. This relationship has been rationalized in terms of partial charges of the atoms participating in H bonding, which can reveal the trend in t h e electrostatic part of total H bond energy. I t can be shown that a short distance between coordination site and acceptor hydrogen increases the H-bond strength substantially, while a long distance shows minor effects as supposed. On the other hand, the opposite effect is observed for the influence of the distance between binding site and donor atom. A comparison of our findings with a new model of transition metal ion facilitated rewinding of denatured DNA proposed hy