Introduction of Cationic Charge into DNA Near the Major Groove Edge of a Guanine•Cytosine Base Pair: Characterization of Oligodeoxynucleotides Substituted with 7-Aminomethyl-7-Deaza-2’-Deoxyguanosine

摘要

The replacement of the 7-N atom on guanine (>G) with a C-H to give 7-deazaguanine (>c⁷G) alters the electronic properties of the heterocyclic base and eliminates a potential major groove cation binding site, which affects the organization of salts and water in the major groove. This has a destabilizing effect on DNA. We report herein the characterization of DNA oligomers containing 7-(aminomethyl)-7-deazaguanine (>1) residues using a variety of spectroscopic and thermodynamic approaches. >1 is an intramolecular model for the major groove binding of cations and basic amino acid residues to >G. In contrast to >c⁷G, the tethering of a cation in the major groove using >1 affords DNA that is as, or more, stable than the corresponding unmodified DNA. The stabilization is associated with the folding enthalpy and hydration.