DNG cytidine: synthesis and binding properties of octameric guanidinium-linked deoxycytidine oligomer Original Research Article

The synthesis of guanidinium-linked cytidyl oligomer (DNG-C8), a cationic DNA analog, and the corresponding cytidine monomers is described. The DNG monomer synthesis was streamlined to produce a shorter route to the final monomer than previously reported for thymidine and subsequent solid-phase synthesis produced an octameric cytidyl DNG strand. Because octameric deoxyguanosine would be used as the complementary strand in our studies, it was necessary to investigate guanosine self-association. Singular value decomposition was used to mathematically deconvolve the spectral data and confirm the presence of transitions due to DNA-G8 self-association. Job plots show the binding stoichiometry of DNG-C8 with DNA-G8 to be 1:1. Thermal denaturation studies of the DNG-C8·DNA-G8 duplex established a Tm⩾90 °C and a ΔG∘=−13.3 kcal mol−1, indicating the DNG-C8·DNA-G8 duplex is over 1000 times more stable than that of DNA-C8·DNA-G8.