The 2D [31P] spin-echo-difference constant-time [13C, 1H]-HMQC experiment for simultaneous determination of 3J(H3'P) and 3J(C4'P) in 13C-labeled nucleic acids and their protein complexes. |
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| Authors: | T Szyperski C Fernández A Ono K Wüthrich M Kainosho |
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| Institution: | Institut für Molekularbiologie und Biophysik, Eidgen?ssische Technische Hochschule-H?nggerberg, Zürich, CH-8093, Switzerland. |
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| Abstract: | A two-dimensional 31P] spin-echo-difference constant-time 13C, 1H]-HMQC experiment (2D 31P]-sedct-13C, 1H]-HMQC) is introduced for measurements of 3J(C4'P) and 3J(H3'P) scalar couplings in large 13C-labeled nucleic acids and in DNA-protein complexes. This experiment makes use of the fact that 1H-13C multiple-quantum coherences in macromolecules relax more slowly than the corresponding 13C single-quantum coherences. 3J(C4'P) and 3J(H3'P) are related via Karplus-type functions with the phosphodiester torsion angles beta and epsilon, respectively, and their experimental assessment therefore contributes to further improved quality of NMR solution structures. Data are presented for a uniformly 13C, 15N-labeled 14-base-pair DNA duplex, both free in solution and in a 17-kDa protein-DNA complex. |
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