Structural Mass Spectrometry

Studying macromolecular machines is not a trivial task. The complexity, asymmetric structure, dynamic properties and low cellular abundance of such large protein assemblies pose a great challenge to established structural biology methods. However, new developments in mass spectrometry led to the birth of a new field, namely, structural mass spectrometry, that can provide key information about complex molecular assemblies. The novelty of this method lies in its ability to probe transient, asymmetric and heterogeneous macromolecular complexes, using very low concentration of sample. Insight into subunit stoichiometry, composition and structural arrangement can be revealed. In addition, the speed of the analysis enables dynamic reactions to be monitored in real time.

The electrospary ionization method is a ‘soft’ ionization technique that preservers the weak non-covalent interactions between molecules enabling the analysis of large biological complexes. In 2002 John Fenn, who developed the method, received the Nobel prize.

We use this cutting-edge mass spectrometry approach to study functional protein machineries involved in the ubiquitin-proteasome pathway. Moreover, we apply an exciting recent breakthrough technology that enables to correlate between the mass of specie to its shape, allowing an additional dimension of characterization. Overall our efforts are directed towards the application and development of the structural mass spectrometry approach in order to address specific questions not readily addressed by other structural methods.

A new hybrid mass spectrometer (Synapt) allows ion mobility separation of electrosprayed ions with concurrent mass analysis. This exciting technology provides an extra dimension of sample separation and above all, it allows the measuring of collision cross sections of a protein complex, hence revealing information on the shape and architecture of the complex.