Nonenzymatic synthesis of RNA and DNA oligomers on hexitol nucleic acid templates: The importance of the A structure

Hexitol nucleic acid (HNA) is an analogue of DNA containing the standard nu cleoside bases, but with a phosphorylated 1,5-anhydrohexitol backbone. HNA oligomers form duplexes having the nucleic acid A structure with complement ary DNA or RNA oligomers. The HNA decacytidylate oligomer is an efficient t emplate for the oligomerization of the 5'-phosphoroimidazolides of guanosin e or deoxyguanosine. Comparison of the oligomerization efficiencies on HNA, RNA, and DNA decacytidylate templates under various conditions suggests st rongly that only nucleic acid double helices with the A structure support e fficient template-directed synthesis when 5'-phosphoroimidazolides of nucle osides are used as substrates.