Development of new 13C-13C distance measurement techniques for applications to proteins in the solid state
We present a new solid state NMR method for 13C- 13C distance measurements, which was tested in a small protein prepared in a microcrystalline form. The experiment uses three-dimensional chemical shift correlation spectroscopy to resolve most of the spectral resonances. We have demonstrated that a large number of internuclear distances can be collected from band selective rotational resonance (BSR2) experiments. We obtained distances of both short and long range (in terms of sequence separation), which could be used to constrain local side chain conformations and a global fold of the protein. Data analysis was carried out using a simplified two-spin model and steady state approximation. Both random and systematic errors were evaluated. BSR2 is potentially a powerful tool for three-dimensional structure determination of proteins in the solid phase.