Duplex formation of the simplified nucleic acid GNA.

Glycol nucleic acid (GNA) has an acyclic backbone of propylene glycol nucleosides that are connected by phosphodiester bonds. This paper characterizes the duplex-formation properties of this simplified nucleic acid. Although single and multiple GNA nucleotides are highly destabilizing if incorporated into DNA duplexes, the two enantiomeric oligomers (S)-GNA and (R)-GNA form antiparallel homoduplexes that are thermally and thermodynamically significantly more stable than analogous duplexes of DNA and RNA. The salt-dependence and Watson-Crick-pairing fidelity of GNA duplexes are similar to those of DNA duplexes, but, apparently, the 2'-deoxyribonucleotide and the propylene glycol backbones are not compatible with each other. This conclusion is further supported by cross-pairing experiments. Accordingly, both (S)- and (R)-GNA strands do not generally pair with DNA. However, (S)-GNA, but not (R)-GNA, forms stable heteroduplexes with RNA in sequences that are low in G:C content. Altogether, the high stability and fidelity of GNA duplex formation in combination with the economical accessibility of propylene glycol building blocks for oligonucleotide synthesis render GNA an attractive candidate for the design of self-assembling materials. They further suggest that GNA could be considered as a potential candidate for a predecessor of RNA during the evolution of life on Earth.