Abstract
With the recent advances in NMR relaxation techniques, protein motions on functionally important timescales can be studied at atomic resolution. Here, we have used NMR-based relaxation experiments at several temperatures and both 600 and 900 MHz to characterize the inherent dynamics of the enzyme cyclophilin-A (CypA). We have discovered multiple chemical exchange processes within the enzyme that form a "dynamic continuum" that spans 20-30 A comprising active site residues and residues proximal to the active site. By combining mutagenesis with these NMR relaxation techniques, a simple method of counting the dynamically sampled conformations has been developed. Surprisingly, a combination of point mutations has allowed for the specific regulation of many of the exchange processes that occur within CypA, suggesting that the dynamics of an enzyme may be engineered.