Development of fast magic angle spinning solid-state NMR methodology to characterize protein dynamics from spin lock relaxation rates.

Solid-state NMR offers not only the ability to calculate protein crystal structure but also dis- tinguish movement and dynamics at individual sites. Transverse relaxation rates (R2, R1rho) can be used to access details of dynamics up to the picosecond range, allowing access to bond movements in the timescale of functionally relevant conformational changes. Our work uses the rate of transverse relaxation in the spin lock plane (R1ρ) at two magic angle spinning (MAS) frequencies (50 and 57.5 kHz) to obtain correlation times and order parameters for 15N-1H bonds in the 56 residue B1 domain from immunoglobulin protein G (GB1). This allows access to motions on the microsecond timescale and provides preliminary support for work by Kurbanov et al. which outlines a Lipari-Szabo model-free framework indicating that the transverse relaxation is dependent upon the magic angle spinning speed.