title: Cross-correlation suppressed T1 and NOE experiments for protein side-chain 13CH2 groups.
abstract: Relaxation measurements of side-chain 13CH2-groups of uniformly 13C labeled human ubiquitin were performed at 600 MHz and 800 MHz magnetic field strength at 30 degrees C. Dipole-dipole cross-correlated relaxation effects in T1 experiments were suppressed by the combination of radio-frequency pulses and pulsed field gradients during the relaxation delay leading to monoexponential relaxation decays that allow a more accurate extraction of the 13C T1 relaxation times. Heteronuclear [1H]-13C NOEs obtained by using different proton saturation schemes indicate that the influence of cross-correlation is small. The experimental T1 and NOE data were interpreted in a model-free way in terms of a generalized order parameter and an internal correlation time.
authors.affiliation: Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA 01610, USA.
authors.forename: Changwen
authors.initials: C
authors.lastname: Jin
authors.forename: Jeanine J
authors.initials: JJ
authors.lastname: Prompers
authors.forename: Rafael
authors.initials: R
authors.lastname: Brüschweiler
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D002250:Carbon Radioisotopes; D006801:Humans; D006838:Hydrocarbons; D008697:Methane / Q000031:analogs & derivatives* / Q000032:analysis*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011506:Proteins / Q000737:chemistry*; D025801:Ubiquitin / Q000032:analysis / Q000737:chemistry
chemical_list: D000596:Amino Acids; D002250:Carbon Radioisotopes; D006838:Hydrocarbons; D011506:Proteins; D025801:Ubiquitin; C030011:carbene; D008697:Methane