title: Optimal methyl labeling for studies of supra-molecular systems.
abstract: Selective methyl labeling combined with HMQC spectroscopy that exploits a TROSY effect in (13)CH(3) spin systems has significantly extended the utility of solution NMR spectroscopy in studies of high molecular weight particles. Herein we compare the utility of (13)CH(3)- versus (13)CHD(2)-labeling of Ile, Leu, Val probes in supra-molecular systems through quantification of relative signal-to-noise ratios in optimized spectra of highly deuterated, (13)CH(3)- and (13)CHD(2)-labeled samples of the half proteasome (alpha(7)alpha(7), 360 kDa). It is shown that the sensitivity of spectra recorded on Ile, Leu, Val (13)CH(3)-labeled samples is between 1.5 and 2 fold higher than the corresponding data sets obtained on alpha(7)alpha(7) with (13)CHD(2) probes. Thus, labeling of supra-molecules with (13)CH(3) isotopomers remains the method of choice, but in applications where (13)CHD(2) moieties are required, sensitivity will in general not be limiting.
authors.affiliation: Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON, M5S 1A8, Canada.
authors.forename: Tomasz L
authors.initials: TL
authors.lastname: Religa
authors.forename: Lewis E
authors.initials: LE
authors.lastname: Kay
mesh_terms: D002247:Carbon Isotopes; D003903:Deuterium; D007532:Isoleucine; D007930:Leucine; D008745:Methylation; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D014633:Valine
chemical_list: D002247:Carbon Isotopes; D011506:Proteins; D007532:Isoleucine; D003903:Deuterium; D046988:Proteasome Endopeptidase Complex; D007930:Leucine; D014633:Valine