Determination of (h2)J(NN) and (h1)J(HN) coupling constants across Watson-Crick base pairs in the Antennapedia homeodomain-DNA complex using TROSY

This paper describes NMR measurements of N-15-N-15 and H-1-N-15 scalar coup lings across hydrogen bonds in Watson-Crick base pairs, (h2)J(NN) and (h1)J (HN), in a 17 kDa Antennapedia homeodomain-DNA complex. A new NMR experimen t is introduced which relies on zero-quantum coherence-based transverse rel axation-optimized spectroscopy (ZQ-TROSY) and enables measurements of (h1)J (HN) couplings in larger molecules. The (h2)J(NN) and (h1)J(HN) couplings o pen a new avenue for comparative studies of DNA duplexes and other forms of nucleic acids free in solution and in complexes with proteins, drugs or po ssibly other classes of compounds.