Unambiguous through-bond sugar-to-base correlations for purines in 13C,15N-labeled nucleic acids: the HsCsNb,HsCs(N)bCb, and HbNbCb experiments.

A set of three 3D (1H,13C,15N) triple-resonance correlation experiments has been designed to provide H1'-H8 intraresidue sugar-to-base correlations in purines in an unambiguous and efficient manner. Together, the HsCsNb, HsCs(N)bCb, and HbNbCb experiments correlate the H1' sugar proton to the H8 proton of the attached base by means of the (H1', C1', N9, C8, H8) heteronuclear scalar coupling network. The assignment strategy presented here allows for unambiguous H1'-H8 intraresidue correlations, provided that no two purines have both the same H1' and C1' chemical shifts and the same C8 and N9 chemical shifts. These experiments have yielded H1'-H8 intraresidue sugar-to-base correlations for all five guanosines in the [13C,15N] isotopically labeled RNA duplex r(GGCGCUUGCGUC)2.