Before revision:  A strong correlation between the tumbling of the protein and the transitions of the X4 and X5 dihedral angles of the MTSL , was observed with a consequent effect also the distribution of the nitroxide (NO) group in the space . Theoretical EPR spectra calculated from opportunely selected MD frames showing interactions between the MTSL and residues of the protein were seen to be in good agreement with the experimental EPR spectrum , indicating a predominance of some conformational states of the full spin-labelled system.
After revision:  A strong correlation between the tumbling of the protein and the transitions of the X4 and X5 dihedral angles of the MTSL , was observed with a consequent effect also the distribution of the nitroxide (NO) group in space and time. The theoretical EPR spectra were calculated using selected configurations of MTSL probing different micro-environments of the protein were seen to be in good agreement with the experimental EPR spectrum , indicating a predominance of some conformational states of the full spin-labelled system.