Resolution Enhancement in Multidimensional Solid-State NMR Spectroscopy of Proteins using Spin-State Selection
A new experimental approach is introduced which leads to significant resolution enhancement in multidimensional 13C-13C correlation experiments of microcrystalline systems. Spin-state-selective techniques, adapted for solid-state NMR, are used for removing the J-coupling contribution to the 13C lineshapes. Combination of the spin-state-selective elements and standard ZQ or DQ solid-state NMR mixing sequences allows to perform a spin-state-selective polarization transfer. In addition to the resolution improvement, the new technique enables to distinguish "direct" cross peaks involving covalently bound nuclei from "relayed" cross peaks.