title: Interaction of sodium and potassium ions with sandwiched cytosine-, guanine-, thymine-, and uracil-base tetrads.
abstract: Nucleic acid tetraplexes and lipophilic self-assembling G-quadruplexes contain stacked base tetrads with intercalated metal ions as basic building blocks. Thus far, quantum-chemical studies have been used to explore the geometric and energetic properties of base tetrads with and without metal ions. Recently, for the first time, work on a sandwiched G-tetrad complex has been studied. We report here results of a systematic B3LYP density functional study on sandwiched G-, C-, U-, and T-tetrads with Na+ and K+ at different symmetries that substantially extend the recent work. The results include detailed information on total energies as well as on metal ion tetrad and base-base interaction energies. The geometrical parameters of the sandwiched metal ion complexes are compared to both experimental structures and to calculated geometries of complexes of single tetrads with metal ions. A microsolvation model explains the ion selectivity preference of K+ over Na+ in a qualitative sense.
authors.affiliation: Revotar Biopharmaceuticals AG, Neuendorfstrasse 24a, D-16761 Hennigsdorf, Germany. m.meyer@revotar-ag.de
authors.forename: Michael
authors.initials: M
authors.lastname: Meyer
authors.forename: Alexandre
authors.initials: A
authors.lastname: Hocquet
authors.forename: Jürgen
authors.initials: J
authors.lastname: Sühnel
mesh_terms: D000465:Algorithms; D020029:Base Pairing; D003596:Cytosine / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D011188:Potassium / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D013816:Thermodynamics; D013941:Thymine / Q000737:chemistry*; D014498:Uracil / Q000737:chemistry*
chemical_list: D014498:Uracil; D006147:Guanine; D003596:Cytosine; D012964:Sodium; D013941:Thymine; D011188:Potassium