title: An optimized relaxation-based coherence transfer NMR experiment for the measurement of side-chain order in methyl-protonated, highly deuterated proteins.
abstract: Relaxation violated coherence transfer NMR spectroscopy has emerged as a powerful experimental tool for the quantitative measurement of amplitudes of motion of methyl containing side-chains. Typically, the experiments, performed on proteins that are highly deuterated and methyl-protonated, monitor the build-up of methyl (1)H double-quantum magnetization. Because all three protons in a methyl group are degenerate, such coherences can only result from differential relaxation of transverse magnetization components, which in turn reflect the extent and time-scale of motion of the methyl probe [Tugarinov, V., Sprangers, R.; Kay, L.E. J. Am. Chem. Soc. 2007, 129, 1743-1750]. We show here that a 50% gain in the sensitivity of the experiment can be achieved through selection of (1)H triple-quantum coherence, thereby significantly increasing the utility of the approach. A theoretical treatment rationalizes the sensitivity gain that is subsequently verified through experiment. The utility of the methodology is demonstrated on a number of proteins, including the 360 kDa α(7)α(7) "half-proteasome".
authors: Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland 20742, United States.
authors: Hechao
authors: H
authors: Sun
authors: Lewis E
authors: LE
authors: Kay
authors: Vitali
authors: V
authors: Tugarinov
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D003903:Deuterium / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D011506:Proteins / Q000737:chemistry*; D011522:Protons; D011789:Quantum Theory
chemical_list: D002247:Carbon Isotopes; D011506:Proteins; D011522:Protons; D003903:Deuterium