Stabilization of tandem dG-dA base pairs in DNA-hairpins:replacement of the canonical bases by 7-deaza-7-propynylpurines

摘要

The stabilizing effect of 7-propynylated 7-deazapurine nucleosides on DNA-hairpins and DNA-duplexes containing d(GA) mismatches was investigated.The corresponding oligonucleotides were synthesized using solid-phase synthesis.For this purpose,the phosphoramidite of 7-deaza-7-propynyl-2'-deoxyadenosine (3c) was prepared.The incorporation of 3c instead of dA into the tandem d(GA) base pair of a DNA-hairpin alters the secondary structure,but has a positive effect on the duplex stability.A complete replacement of the canonical nucleosides of the tandem ' d(GA) base pair by 3c and 7-deaza-7-propynyl-2'-deoxyguanosine results in a significant base pair stabilization.