Highly Selective Stable Isotope Labeling of Histidine Residues by Using a Novel Precursor in E. coli-Based Overexpression Systems

The importance of NMR spectroscopy in unraveling the structural and dynamic properties of proteins is ever-expanding owing to progress in experimental techniques, hardware development, and novel labeling approaches. Multiple sophisticated methods of aliphatic residue labeling can be found in the literature, whereas the selective incorporation of NMR active isotopes into other amino acids still holds the potential for improvement. In order to close this methodological gap, we present a novel metabolic precursor for cell-based protein overexpression to assemble C-13/H-2 isotope patterns in the peptide backbone, as well as in side chain positions of a mechanistically distinguished histidine residue.