Structure, stability and application to functional DNA/RNA of unique quadruplex.

We have developed a direct and unambiguous method for discrimination of intra- and intermolecular hydrogen bonds in a symmetric multimer. The method was applied to a symmetric dimer of d(GGAGGAGGAGGA) (GGA 12-mer) and has provided decisive information on its multimeric architecture. Then, the values for scalar couplings across hydrogen bonds for G:G and G:A base pairs in the G(:A):G(:A):G(:A):G heptad formed by GGA 12-mer were determined. This determination has provided an insight into the stability of the heptad. Moreover, GGA 12-mer has been incorporated into functional DNA, and unique structural features of GGA 12-mer have been successfully utilized to regulate the activity of functional DNA.