Changes in Calmodulin Main-Chain Dynamics upon Ligand Binding Revealed by Cross-Correlated NMR Relaxation Measurements

摘要

It has long been recognized that proteins are dynamic systems and that this dynamic quality is important to protein function.NMR spectroscopy has evolved to become a powerful method for experimental quantification of conformational dynamics of proteins.Historically,the sampling of ~15N relaxation due to dipole-dipole interactions with its attached hydrogen has been the principal measurement of subnanosecond motion of the polypeptide backbone in proteins.In general,these experiments have suggested that the protein backbone is highly rigid on the picosecond-nanosecond time scale.In an effort to more fully characterize the motion of the polypeptide chain of proteins,we have developed a complementary approach based on the transverse cross-correlated relaxation rates between "CO chemical shift anisotropy and the ~13CO-~13Ca dipolar interactions which are sensitive to the motion the ~13CO-~13Ca bond vector.