The presence of local anisotropic interactions in solid state NMR gives a unique opportunity to obtain information from specific probes in the molecule. These interactions, primarily governed by chemical shift anisotropy (CSA) and dipolar couplings of the molecule, give rise to signals that can be manipulated with pulse sequences and Magic angle spinning (MAS) of the rotor. Among the various experiments that have been designed to extract motional details, R1ρ (rotating frame relaxation) is a common technique to extract the millisecond to microseconds level motion. Theoretical frameworks such as the Redfield theory exist to get the relaxation rates and further for fitting it to a model of motion, the Model free approach is used which provides the dynamics information in terms of two parameters – order parameter (S2) and correlation times (τc). Along with the protein dynamics, various interference effects in the pulse sequences can complicate the extraction of accurate information from the experiments. Thus, we work on designing experimental strategies based on NMR pulse sequences and protein isotope labelling methodologies backed up by numerical simulations to mitigate these effects and extract precise motional details.
