title: Estimates of methyl 13C and 1H CSA values (Deltasigma) in proteins from cross-correlated spin relaxation.
abstract: Simple pulse schemes are presented for the measurement of methyl (13)C and (1)H CSA values from (1)H-(13)C dipole/(13)C CSA and (1)H-(13)C dipole/(1)H CSA cross-correlated relaxation. The methodology is applied to protein L and malate synthase G. Average (13)C CSA values are considerably smaller for Ile than Leu/Val (17 vs 25 ppm) and are in good agreement with previous solid state NMR studies of powders of amino acids and dipeptides and in reasonable agreement with quantum-chemical DFT calculations of methyl carbon CSA values in peptide fragments. Small averaged (1)H CSA values on the order of 1 ppm are measured, consistent with a solid state NMR determination of the methyl group (1)H CSA in dimethylmalonic acid.
authors.affiliation: Protein Engineering Network Center of Excellence, Department of Medical Genetics, University of Toronto, Toronto, Ont, Canada, M5S 1A8.
authors.forename: Vitali
authors.initials: V
authors.lastname: Tugarinov
authors.forename: Christoph
authors.initials: C
authors.lastname: Scheurer
authors.forename: Rafael
authors.initials: R
authors.lastname: Brüschweiler
authors.forename: Lewis E
authors.initials: LE
authors.lastname: Kay
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002247:Carbon Isotopes; D004268:DNA-Binding Proteins / Q000737:chemistry; D008292:Malate Synthase / Q000737:chemistry; D008745:Methylation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010462:Peptostreptococcus / Q000737:chemistry; D011522:Protons
chemical_list: D001426:Bacterial Proteins; D002247:Carbon Isotopes; D004268:DNA-Binding Proteins; C116593:L-protein, Peptococcus magnus; D011522:Protons; D008292:Malate Synthase