Joint Composite-Rotation Adiabatic-Sweep Isotope Filtration

Joint composite-rotation adiabatic-sweep isotope filter are derived by combining the composite-rotation [A. C. Stuart, K. A. Borzilleri, J. M. Withka, and A. G. Palmer, J. Am. Chem. Soc. 121, 5346–5347 (1999)] and adiabatic-sweep [C. Zwahlen, P. Legault, S. J. F. Vincent, J. Greenblatt, R. Konrat, and L. E. Kay, J. Am. Chem. Soc. 119, 6711–6721 (1997); Ē. Kupče and R. Freeman, J. Magn. Reson. 127, 36–48 (1997)] approaches. The joint isotope filters have improved broadband filtration performance, even for extreme values of the one-bond 1H-13C scalar coupling constants in proteins and RNA molecules. An average Hamiltonian analysis is used to describe evolution of the heteronuclear scalar coupling interaction during the adiabatic sweeps within the isotope filter sequences. The new isotope filter elements permit improved selective detection of NMR resonance signals originating from 1H spins attached to an unlabeled natural abundance component of a complex in which other components are labeled with 13C and 15N isotopes.