Before revision:  The theoretical  EPR spectra were calculated using selected configurations of MTSL probing different micro-environments of the protein characterized by different polarity. The comparison between the theoretical and experimental 9 GHz and 94 GHz EPR spectra revealed that some fits were in good agreement with the experimental EPR spectra, indicating a predominance of some conformational states of the full spin-labelled system.
After revision:  The theoretical EPR spectra were calculated using configurations representing the interactions between MTSL and water and the tyrosine residue 208 in the C-lobe; and the comparison with experimental EPR spectra revealed that some fits were in good agreement with the experimental EPR spectra, indicating a predominance of some conformational states of the full spin-labelled system.