The ge-2D HNN-COSY experiment has been developed for direct observation of hydrogen bonds in 15N-labeled nucleic acid base pairs by internucleotide 2J(N,N) couplings

Implementation on AVANCE spectrometers equipped with gradient technology.

This experiment was originally described in 98JACS8293 for Watson-Crick base pairs in RNA

Cross-hydrogen bond ^2hJ_N,N coupling constants, ranging from +6 to +10 Hz, has also been measured in:

Hoogsteen base pairs in RNA ( 98JACS8293 and 98PNAS14147)

DNA ( 99JB67, 99JACS6019 and 00JB279)

DNA-protein complex ( 00JB39).

Between NH.....N sidechain of histidines in a protein. ( 99JACS5123)

A related sequence has been proposed for the measurement of H....H/H-N hydrogen bond length in double stranded DNA from ¹J(NH) dipolar couplings ( 01JB361-19).

A suite of ^2HJ_NN schemes have been proposed to correlate proton-proton systems across NH........N hydrogen bonds in nucleic acids ( 01JB289-21). These sequences affords H(NN)H correlations in several types of RNA, DNA and peptide-RNA complexes.

A modified TROSY experiment has also been proposed ( 02JB31-24)

A 2D 1H-15N spectrum is obtained