Side-chain to backbone correlations from solid-state NMR of perdeuterated proteins through combined excitation and long-range magnetization transfers

Abstract

Proteins with excessive deuteration give access to proton detected solid-state NMR spectra of extraordinary resolution and sensitivity. The high spectral quality achieved after partial proton back-exchange has been shown to start a new era for backbone assignment, protein structure elucidation, characterization of protein dynamics, and access to protein parts undergoing motion. The large absence of protons at non-exchangeable sites, however, poses a serious hurdle for characterization of side chains, which play an important role especially for structural understanding of the protein core and the investigation of protein-protein and protein-ligand interactions, e.g. This has caused the perdeuteration approach to almost exclusively be amenable to backbone characterization only. In this work it is shown that a combination of isotropic (13)C mixing with long-range (1)H/(13)C magnetization transfers can be used effectively to also access complete sets of side-chain chemical shifts in perdeuterated proteins and correlate these with the protein backbone with high unambiguity and resolution. COmbined POlarization from long-Range transfers And Direct Excitation (COPORADE) allows this strategy to yield complete sets of aliphatic amino acid resonances with reasonable sensitivity.