A 1H nOe and CD study of the salt-concentration dependence of the structure of d(G-C)

Intra- and internucleotide 1H nuclear Overhauser effects (nOes) have been observed in the synthetic decancleoside nonaphosphate d(G-C)5 at low and high salt concentrations, and in conditions under which duplex formation is complete. Comparison of the nOes with interproton distances derived from model and X-ray structures suggest that the duplex is right-handed up to a sodium chloride concentration of 4M, in contrast to the behaviour of poly [d(G-C)]. C.D. spectra are consistent with this suggestion.