Characterization of hydrogen bond lengths in Watson-Crick base pairs by cross-correlated relaxation

Hydrogen bond lengths in Watson-Crick base pairs can be characterized by cross-correlated relaxation between H-1 chemical shift anisotropy and dipole-dipole coupling of H-1 and its hydrogen bond acceptor N-15. As a reference, the cross-correlated relaxation between H-1 chemical shift anisotropy and dipole-dipole coupling of H-1 and its hydrogen bond donor N-15 is used. With the two measured cross-correlated relaxation rates, an apparent hydrogen bond length can be determined, which is composed by the hydrogen bond length multiplied by a term representing the amplitude of inter-base motions. Data are presented for the (15)N3-(1)H3 . . . (15)N1 hydrogen bonds in A = T base pairs of the Antennapedia homeodomain-DNA complex with a correlation time of global rotational diffusion of 20 ns. (C) 2001 Academic Press.