Pseudomultidimensional NMR by spin-state selective off-resonance decoupling.
An alternate technique for accurately monitoring the chemical shift in multidimensional NMR experiments using spin-state selective off-resonance decoupling is presented here. By applying off-resonance decoupling on spin S during acquisition of spin I, we scaled the scalar coupling J(I,S) between the spins, and the residual scalar coupling turns out to be a function of the chemical shift of spin S. Thus, the chemical shift information of spin S is indirectly retained, without an additional evolution period and the accompanying polarization transfer elements. The detection of the components of the doublet using spin-state selection enables an accurate measurement of the residual scalar coupling and a precise value for the chemical shift, concomitantly. The spin-state selection further yields two subspectra comprising either one of the two components of the doublet and thereby avoiding the overlap problems that arise from off-resonance decoupling. In general, spin-state selective off-resonance decoupling can be incorporated into any pulse sequence. Here, the concept of spin-state selective off-resonance decoupling is applied to 3D (13)C or (15)N-resolved [(1)H,(1)H]-NOESY experiments, adding the chemical shift of the heavy atom attached to the hydrogen ((13)C or (15)N nuclei) with high resolution resulting in a pseudo-4D. These pseudo-4D heavy-atom resolved [(1)H, (1)H]-NOESY experiments contain chemical shift information comparable to that of 4D (13)C or (15)N-resolved [(1)H,(1)H]-NOESY, but with an increase in chemical shift resolution by 1-2 orders of magnitude.
Grace
Christy Rani R
CR
Structural Biology Laboratory, The Salk Institute, La Jolla, California 92037, USA.
Riek
Roland
R
D002247:Carbon Isotopes; D007930:Leucine / Q000737:chemistry; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D025801:Ubiquitin / Q000737:chemistry
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D011522:Protons; D025801:Ubiquitin; D007930:Leucine