The NMR chemical shifts of a substance in a complex mixture strongly depend on the composition of the mixture itself, as many weak interactions occur that are hardly predictable. Chemical shift variability is the major obstacle... Read More


An integrated approach which combines in-cell NMR spectroscopy with optical and X-ray fluorescence microscopy was developed to describe the intracellular maturation state of human Cu,Zn-SOD1.  Read More

NCB N terminal

Structural and biophysical evidences define the early steps of iron-sulfur protein maturation in the cytosol, demonstrating that  glutaredoxin-3 passes [2Fe-2S] clusters to anamorsin during a protein-protein interaction mediated by their N-terminal domains.  Read More 

nature chemistry

Dynamic nuclear polarization (DNP) in liquid solutions can enhance 13C NMR signals at magnetic fields of 3 T and room temperature up to three orders of magnitude. Read More  Highlighted in Angewandte Chemie

CERM research on covers


SedNMR: On the Edge between Solution and Solid-State NMR  

Bertini, I., Luchinat, C., Parigi, G., and Ravera, E.

Accounts Chemical Research, 2013



Solid-state NMR (SS-NMR) of proteins requires that those molecules be immobilized, usually by crystallization, freezing, or lyophilization. However, self-crowding can also slow molecular rotation sufficiently to prevent the nuclear interactions from averaging. To achieve self-crowding, researchers can use a centrifugal field to create a concentration gradient or use regular ultracentrifugation to produce highly concentrated, gel-like solutions. Thus sedimented solute NMR (SedNMR) provides a simple method to prepare biological samples for SS-NMR experiments with minimal perturbation. This method may also give researchers a way to investigate species that are not otherwise accessible by NMR. We induce the sedimentation in one of two ways: (1) by the extreme centrifugal force exerted during magic angle spinning (MAS-induced sedimentation or in situ) or (2) by an ultracentrifuge (UC-induced sedimentation or ex situ).

Sedimentation is particularly useful in situations where it is difficult to obtain protein crystals. Furthermore, because the proteins remain in a largely hydrated state, the sedimented samples may provide SS-NMR spectra that have better resolution than the spectra from frozen solutions or lyophilized powders. If sedimentation is induced in situ, the same protein sample can be used for both solution and SS-NMR studies.

Finally, we show that in situ SedNMR can be used to detect the NMR signals of large molecular adducts that have binding constants that are too weak to allow for the selective isolation and crystallization of the complexed species. We can selectively induce sedimentation for the heaviest molecular species. Because the complexed molecules are subtracted from the bulk solution, the reaction proceeds further toward the formation of complexes.

Link to full article




Solid-state NMR of proteins sedimented by ultracentrifugation

Bertini, I., Luchinat, C., Parigi, G., Ravera, E., Reif, B., and Turano, P.

Proc.Natl.Acad.Sci.USA, 108, 10396-10399, 2011



Relatively large proteins in solution, spun in NMR rotors for solid samples at typical ultracentrifugation speeds, sediment at the rotor wall. The sedimented proteins provide high-quality solid-state-like NMR spectra suitable for structural investigation. The proteins fully revert to the native solution state when spinning is stopped, allowing one to study them in both conditions. Transiently sedimented proteins can be considered a novel phase as far as NMR is concerned. NMR of transiently sedimented molecules under fast magic angle spinning has the advantage of overcoming protein size limitations of solution NMR without the need of sample crystallization/precipitation required by solid-state NMR.

Link to journal online abstract

Link to full article

link to Chemistry World comments 

link to C&EN news 

link to Nature Chemistry 'Research highlights' 

link to Nature Methods  'Research highlights'

link to Nature Chemistry  'News & Views'

link F1000 Highlight