title: Measuring the chi 1 torsion angle in protein by CH-CH cross-correlated relaxation: a new resolution-optimised experiment.
abstract: Here we introduce an experiment with high sensitivity and resolution for the measurement of CH-CH dipolar-dipolar cross-correlated relaxation rates (CCRR) in protein side-chains. The new methodology aims to the determination of structural and dynamical parameters around the torsion angle chi(1) by measuring C(alpha)H(alpha)-C(beta)H(beta) cross-correlated relaxation rates. The method is validated on the protein ubiquitin: the chi(1) angles determined from the CCRR data are compared with the chi(1) angles of a previously determined NMR structure. The agreement between the two data sets is excellent for most residues. The few discrepancies that were found between the CCR-derived chi(1) angles and the angles of the previously determined NMR structure could be explained by taking internal motion into account. The new methodology represents a very powerful tool to determine both structure and dynamics of protein side-chains in only one experiment.
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Department of NMR-based Structural Biology, Am Fassberg 11, D-37077 Göttingen, Germany. taco@nmr.mpibpc.mpg.de
authors.forename: Teresa
authors.initials: T
authors.lastname: Carlomagno
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bermel
authors.forename: Christian
authors.initials: C
authors.lastname: Griesinger
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D025801:Ubiquitin / Q000737:chemistry
chemical_list: D011506:Proteins; D025801:Ubiquitin