Modified purine nucleosides as dangling ends of DNA duplexes: the effect of the nucleobase polarizability on stacking interactions

Abstract

Base-modified nucleotide residues have been appended to the 5′-terminus of the self-complementary oligo-2′-deoxynucleotide duplex [5′-d(CGCGCG)]₂ as dangling ends. Temperature-dependent UV measurements on the resulting oligomers indicate generally higher thermal stabilities (T_m) compared to that without an overhanging end. The duplex stabilization (ΔT_m) was correlated with the molecular polarizability (α_m) of the base of the pendant nucleoside showing that: the higher the molecular polarizability α_m of a dangling nucleobase, the higher the thermal stability of the DNA duplex.