title: 1H,13C-1H,1H dipolar cross-correlated spin relaxation in methyl groups.
abstract: Relaxation in methyl groups is strongly influenced by cross-correlated interactions involving the methyl dipoles. One of the major interference effects results from intra-methyl (1)H-(13)C, (1)H-(1)H dipolar interactions, leading to significant differences in the relaxation of certain multiplet components that contribute to double- and zero-quantum (1)H-(13)C spectra. NMR experiments are presented for the measurement of this differential relaxation effect. It is shown that this difference in relaxation between double- and zero-quantum multiplet components can be used as a sensitive reporter of side chain dynamics and that accurate methyl axis order parameters can be measured in proteins that tumble with correlation times greater than approximately 5 ns.
authors.affiliation: Protein Engineering Network Centres of Excellence and the Department of Medical Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
authors.forename: Vitali
authors.initials: V
authors.lastname: Tugarinov
authors.forename: Lewis E
authors.initials: LE
authors.lastname: Kay
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002247:Carbon Isotopes; D004926:Escherichia coli / Q000378:metabolism; D006859:Hydrogen / Q000737:chemistry*; D007930:Leucine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015233:Models, Statistical; D009584:Nitrogen / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D013696:Temperature; D013997:Time Factors; D014633:Valine / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D002244:Carbon; D006859:Hydrogen; D007930:Leucine; D014633:Valine; D009584:Nitrogen