Sensitivity-Enhanced MQ–HCN–CCH–TOCSY and MQ–HCN–CCH–COSY Pulse Schemes for 13C/15N Labeled RNA Oligonucleotides

Sensitivity enhanced multiple-quantum 3D HCN–CCH–TOCSY and HCN–CCH–COSY experiments are presented for the ribose resonance assignment of 13 C/ 15 N-labeled RNA sample. The experiments make use of the chemical shift dispersion of N1/N9 of pyrimidine/purine to distinguish the ribose spin systems. They provide a complementary approach for the assignment of ribose resonance to the currently used HCCH–COSY and HCCH–TOCSY type experiments in which either 13 C or 1 H is utilized to separate the different ribose spin systems. The pulse schemes have been demonstrated on a 23-mer 13 C/ 15 N-labeled RNA aptamer complexed with neomycin and tested on a 32-mer RNA complexed with a 23-residue peptide.