3D HCCH3 -TOCSY for resonance assignment of methyl-containing side chains in 13C-labeled proteins

Citation

Uhrin D, Uhrinova S, Leadbeater C, Nairn J, Price NC & Barlow PN (2000) 3D HCCH3 -TOCSY for resonance assignment of methyl-containing side chains in 13C-labeled proteins. Journal of Magnetic Resonance, 142 (2), pp. 288-293. https://doi.org/10.1006/jmre.1999.1951

Abstract
Two 3D experiments, (H)CCH3-TOCSY and H(C)CH3-TOCSY, are proposed for resonance assignment of methyl-containing amino acid side chains. After the initial proton–carbon INEPT step, during which either carbon or proton chemical shift labeling is achieved (t1), the magnetization is spread along the amino acid side chains by a carbon spin lock. The chemical shifts of methyl carbons are labeled (t2) during the following constant time interval. Finally the magnetization is transferred, in a reversed INEPT step, to methyl protons for detection (t3). The proposed experiments are characterized by high digital resolution in the methyl carbon dimension (t2max = 28.6 ms), optimum sensitivity due to the use of proton decoupling during the long constant time interval, and an optional removal of CH2, or CH2 and CH, resonances from the F2F3 planes. The building blocks used in these experiments can be implemented in a range of heteronuclear experiments focusing on methyl resonances in proteins. The techniques are illustrated using a 15N, 13C-labeled E93D mutant of Schizosacharomyces pombe phosphoglycerate mutase (23.7 kDa).

Keywords
3D NMR; phosphoglycerate mutase; HCCH-TOCSY; protein side chains; methyl-containing amino acids; Proteins; Amino acids Metabolism; Mutagenesis

Journal
Journal of Magnetic Resonance: Volume 142, Issue 2