Access to Cα Backbone Dynamics of Biological Solids by 13C T1 Relaxation and Molecular Dynamics Simulation

We introduce a labeling scheme for magic angle spinning (MAS) solid-state NMR that is based on deuteration in combination with dilution of the carbon spin system. The labeling strategy achieves spectral editing by simplification of the H alpha C alpha and aliphatic side chain spectral region. A reduction in both proton and carbon spin density in combination with fast spinning (>= 50 kHz) is essential to retrieve artifact-free 13C-R1 relaxation data for aliphatic carbons. We obtain good agreement between the NMR experimental data and order parameters extracted from a molecular dynamics (MD) trajectory, which indicates that carbon based relaxation parameters can yield complementary information on protein backbone as well as side chain dynamics.