For the first time, we have demonstrated the site-resolved measurement of reliable (i.e., free of interfering effects) N-15 R-1 rho relaxation rates from a solid protein to extract dynamic information on the microsecond time scale. N-15 R-1 rho NMR relaxation rates were measured as a function of the residue number in a N-15,H-2-enriched (with 10-20% back-exchanged protons at labile sites) microcrystalline SH3 domain of chicken alpha-spectrin. The experiments were performed at different temperatures and at different spin-lock frequencies, which were realized by on- and off-resonance spin-lock irradiation. The results obtained indicate that the interfering spin-spin contribution to the R-1 rho rate in a perdeuterated protein is negligible even at low spin-lock fields, in contrast to the case for normal protonated samples. Through correlation plots, the R-1 rho rates were compared with previous data for the same protein characterizing different kinds of internal mobility.