title: Cross-correlated spin relaxation effects in methyl 1H CPMG-based relaxation dispersion experiments: complications and a simple solution.
abstract: Artifacts associated with the measurement of methyl (1)H single quantum CPMG-based relaxation dispersion profiles are described. These artifacts arise due to the combination of cross-correlated spin relaxation effects involving intra-methyl (1)H-(1)H dipolar interactions and imperfections in (1)H refocusing pulses that are applied during CPMG intervals that quantify the effects of chemical exchange on measured transverse relaxation rates. As a result substantial errors in extracted exchange parameters can be obtained. A simple 'work-around' is presented where the (1)H chemical shift difference between the exchanging states is extracted from a combination of (13)C single quantum and (13)C-(1)H multiple quantum dispersion profiles. The approach is demonstrated with an application to a folding/unfolding reaction involving a G48M mutant Fyn SH3 domain.
authors.affiliation: Contribution from the Protein Engineering Network Centers of Excellence and the Department of Medical Genetics, The University of Toronto, Ontario, Canada.
authors.forename: Dmitry M
authors.initials: DM
authors.lastname: Korzhnev
authors.forename: Anthony K
authors.initials: AK
authors.lastname: Mittermaier
authors.forename: Lewis E
authors.initials: LE
authors.lastname: Kay
mesh_terms: D016477:Artifacts; D002247:Carbon Isotopes / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D008962:Models, Theoretical; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011489:Protein Denaturation; D017510:Protein Folding; D011518:Proto-Oncogene Proteins / Q000737:chemistry; D051076:Proto-Oncogene Proteins c-fyn; D012984:Software; D013696:Temperature; D018909:src Homology Domains; D019061:src-Family Kinases / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D011518:Proto-Oncogene Proteins; D006859:Hydrogen; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases