Shortly after the introduction of electrospray ionization (ESI) that revolutionized the MS analysis of biomolecules at the end of the 80s, several groups observed the presence of non-covalent complexes in the gas phase. First limited to small complexes, instrumental developments progressively enabled the analysis of increasingly larger complexes such as GroEL, the proteasome or even mega-Da assemblies such as ribosomes or viral capsids. Within the past 10 years, non-covalent or native MS, has emerged and is now an integrative part of structural biology, providing a series of information on the structure and dynamics of protein complexes (Figure 1).
The toolbox of structural mass spectrometrists has also been further completed by ion mobility MS (IM-MS). By acting like a “gas phase capillary electrophoresis”, this method enables brings an additional dimension of separation, virtually increasing the peak capacity of the instrument allowing not only spectrum cleaning but also the detection of subtle conformational changes or differences in the unfolding pattern upon ligand binding.
Figure 1. Information obtained by native MS and ion mobility
Protein complexes (~ 10 µl at 10 µM i.e 100 pmol / 2.5 µg for a 25 kDa protein) are desalted (Biospin, Zeba, Vivaspin, dialysis) and directly infused on our Nanomate (Advion) coupled to our SynaptG2Si (Figure 2, Left) or Q-Ex-HFX-Biopharma (Figure 2, Middle).
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Figure 2. Our nanomate autosamplers (Advion) coupled to the SynaptG2Si (Waters, left) and Q-Ex-HFX-Biopharma (Thermo). The H-Class-Bio system can be used for SEC-Native MS.
Alternatively, protein complexes can be separated online by Size Exclusion Chromatograpy (BEH on a H-Class-Bio Acquity UPLC, Waters, Figure 2, Right) and the oligomers directly analysed by Native (Ion-mobility) MS.
2021
Erb S, Cianférani S, Marcoux J. Hands on Native Mass Spectrometry Analysis of Multi-Protein Complexes. Methods in Molecular Biology. 2247:173-191.
2019
Guillet V, Bordes P, Bon C, Marcoux J, Gervais V, Julie Sala A, Dos Reis S, Slama N, Mares-Mejía I, Cirinesi AM, Genevaux P, Mourey L. Structural insights into chaperone addiction of toxin-antitoxin systems. Nature Communications. 10(1):782.