Thymine-metal ion interactions: relevance for thymine quartet structures

JBIC Journal of Biological Inorganic Chemistry - Tập 6 - Trang 378-389 - 2001
Eva Freisinger1, Arnd Schimanski1, Bernhard Lippert1
1Fachbereich Chemie, Universität Dortmund, Dortmund, Germany

Tóm tắt

Apart from their function as counter ions for the charge neutralization of nucleic acids, alkali metal ions play important roles in stabilizing particular multistranded nucleic acids, e.g. guanine quartets in telomeres and uracil (U) or thymine (T) quartets. Here X-ray crystal structure determinations of a series of alkali metal ions (Na+, K+, Rb+, Cs+) as well as of Mg2+ and H5O2 + adducts with the model bases 1-methylthymine and 1-ethylthymine are reported, which bear relevance to the question of thymine quartet (T4) geometries. The compounds isolated differ in their stoichiometries (T:M=4:1, 2:1, 1:1), and the ways the metal ions interact with the bases. The two extremes are exclusive metal coordination to exocyclic oxygen atoms of the T bases and exclusive H bonding between M aqua cations and the bases.