“…The application of heteronuclear-based NMR experiments to oligonucleotides has provided many dramatic advantages that had previously been realized with isotopical labeling of protein samples. Uniform isotopic labeling of oligonucleotides now allows the unambiguous assignment of resonances using through-bond correlated NMR experiments, like the HCP Marino et al, 1994a;Varani et al, 1995), HCN (Sklenar et al, 1993(Sklenar et al, , 1994(Sklenar et al, , 1996Farmer et al, 1993Farmer et al, , 1994Tate et al, 1993;Simorre et al, 1995Simorre et al, , 1996Marino et al, 1997), and HCP-CCH-TOCSY (Marino et al, 1994b;Wijmenga et al, 1995), and limits reliance on the more ambiguous NOE-based assignment of sequential connectivity. In addition, the extraction of NOE-derived distance restraints is facilitated by the increased resolution obtained by combining NOESY experiments with evolution periods of heteronuclear chemical shifts Varani et al, 1996;Allain and Varani, 1997).…”