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 (DeltaT(m)) was correlated with the molecular polarizability (a(m)) of the base of the pendant nucleoside showing that: the higher the molecular polarizability a(m) of a dangling nucleobase, the higher the thermal stability of the DNA duplex.