Assignment of Proton Resonances and Conformational Characterization of Oligodeoxyribonucleic Acid d(CCGTACGG)in Solution

Lycobetaine Prepared from lycorine is a new anticancer agent.The experimental and quantum Pharmacological studies revealed that lycobetaine can interact with DNA by intercalation,preferentially into GO base pairs.In order to provide detailed interaction model of lycobetaine-DNA,a self-complementary octanucleotide d(CCGTACGG)was designed and synthesized by using new HELP(high efficieney liquid phase)According to its nature,the sample was prepared to the desired final concentration by adding salt and buffer solutions.Two-dimensional 1H-1H COSY and NOESY spectra in 99.8%D2O and 95% H2O were recorded for the duplex,and the NMR techniques of presaturation and WATERGATE were applied to water suppression.Protons of every spin system were identified by their scalar couplings,then through their spacial couplings all protons in the molecule were assigned except the poorly resolved H5'and H5"resonanced. The chemical shifts of exchangeable protons and NOE intensities of nonexchangeable protons indicate qualitatively that the d(CCGTACGG)helix is right-handed B-DNA in aqueous solution.