Thermodynamics of dimerization of parallel quadruplex DNAs through the end-to-end stacking of 3'-terminal G-quartets.

DNA sequence d(TTAGGG) spontaneously forms all-parallel G-quadruplex DNA in the presence of KV We have shown that G-quadruplex DNAs formed from the related sequences undergo dimerization through the intermolecular end-to-end stacking of the 3'-terminal G-quartets. 2' 3 We found that the coexistence of G-quadruplex DNAs formed from two different sequences results in the formation of "hetero-dimer", in addition to "homo-dimer". Thermodynamic characterization of the dimerization process revealed a compensatory relationship between the enthalpy and entropy changes of the process.