Rapid interpretation of protein backbone rotation dynamics directly from spin relaxation data

Besides structure, protein dynamics is pivotal for their functions, particularly for intrinsically disordered proteins (IDPs) that do not fold to a fixed 3D structure. Rapid rotations of chemical bonds in proteins can be detected measuring NMR spin relaxation rates, but interpretation of protein dynamics from the experimental data is arduous for IDPs or molecular assemblies with complex dynamic landscape. Here we demonstrate numerically that the total effective correlation times of protein backbone N-H bond rotations, τeff , can be calculated from experimentally measured transverse 15N spin relaxation rates, R2, using linear relation. Using molecular dynamics (MD) simulations, we show this for wide range of proteins, from short peptides to partially dis- ordered proteins and peptides in micelles. Significant practical advance of the result is demonstrated by interpreting dynamics of partially disordered proteins that are beyond the scope of current approaches to interpret spin relaxation rate experiments.