Combined Solution- and Magic Angle Spinning NMR Reveals Regions of Distinct Dynamics in Amyloid beta Protofibrils

Solid-state magic angle spinning (MAS) NMR has emerged as an important tool for investigations of protein aggregates and amyloid fibrils, which are not accessible for solution NMR experiments. We recently presented a structural model for amyloid beta (A beta) protofibrils based on MAS-NMR data. The absence of resonances for the N-terminus of A beta in this dataset suggested that it might be disordered and more dynamic than the structural core. We here provide evidence for a distinct dynamic regime in the N-terminal part of the peptide and show that the structural characteristics of this region can be elucidated using C-13-detected solution NMR. The results shed more light on the structural properties of pre-fibrillar A beta species and demonstrate the potential of combining MAS and solution NMR experiments for the characterization of structure and dynamics of complex protein assemblies.