Stereospecific Leu/Val methyl labeling: An important technology for NMR studies of high-molecular-weight complexes

The development of modern biomolecular solution NMR spectroscopy has paralleled innovations in labeling technologies. For example, early advances in heteronuclear double- and triple-resonance NMR spectroscopy were closely coupled to the emergence of methodologies for the effective uniform labeling of biomolecules with ¹⁵N and/or ¹³C. Despite arguments that uniform ¹³C (U-¹³C) labeling would be prohibitively expensive, the high demand for U-¹³C-labeled precursors has significantly lowered costs, and the preparation of biomolecules with ¹³C incorporation is most often the approach of choice for NMR studies. As the size of the system studied increases, both the sensitivity and the resolution of the resulting spectra suffer, and this has led to the development of amide-TROSY-based experiments that are significantly improved through the use of perdeuteration.