Determination of slow motions in extensively isotopically labeled proteins by magic-angle-spinning 13C-detected 15N exchange NMR

A solid-state NMR exchange technique for detecting slow segmental dynamics in proteins is introduced. The technique exploits motion-induced incomplete refocusing of amide 15N chemical shift anisotropy under magic angle spinning. Slow motions on the millisecond timescales are detected as reduced NMR signals. Detection of 13C magnetization transferred from 15N allows the identification of mobile residues with high resolution. This exchange technique is demonstrated on two proteins with opposite motional properties. Combined with extensive 13C and 15N labeling, this high-resolution exchange NMR technique allows for the first time the efficient determination of slow dynamics at multiple residues of proteins.