Abstract2 H spin relaxation NMR experiments to study the dynamics of deuterated backbone α-positions, D α , are developed. To date, solution-state 2 H relaxation measurements in proteins have been confined to side-chain deuterons -primarily 13 CH 2 D or 13 CHD 2 methyl groups. It is shown that quantification of 2 H relaxation rates at D α backbone positions and the derivation of associated order parameters of C α -D α bond vector motions in small [U-15 N, 13 C, 2 H]-labeled proteins is feasible with reasonable accuracy. The utility of the developed methodology is demonstrated on a pair of proteins -ubiquitin (8.5 kDa) at 10°C, 27°C, and 40°C, and a variant of GB1 (6.5 kDa) at 22°C. In both proteins, the D α -derived parameters of the global rotational diffusion tensor are in good agreement with those obtained from 15 N relaxation rates. Semi-quantitative solution state NMR measurements yield an average value of the quadrupolar coupling constant, QCC, for D α sites in proteins equal to 174 kHz. Using the uniform value of QCC for all D α sites, we show that C α -D α bond vectors are motionally distinct from the backbone amide N-H bond vectors, with 2 H-derived squared order parameters of C α -D α bond vector motions, S 2 CαDα , on average slightly higher than their N-H amides counterparts, S 2 NH . For ubiquitin, the 2 H-derived backbone mobility compares well with that found in a 1-μs molecular dynamics simulation.