Perdeuteration/site-specific protonation approaches for high-molecular-weight proteins

Among the factors that limit the application of nuclear magnetic resonance (NMR) to biological macromolecules are increasing resonance overlap and fast transverse relaxation. Multidimensional NMR combined with 13C and 15N labeling has alleviated these problems temporarily; however, they resurface at molecular weight (mol wt) in excess of 30 kDa. Combined perdeuteration/site-specific protonation together with segmental labeling, transverse relaxation-optimized spectroscopy (TROSY), and residual dipolar couplings have all helped to dramatically extend the mol wt limit. This article describes some of the practical aspects of the combined perdeuteration/site-specific protonation approach, which has proved so useful in the global fold determination of large proteins.