Hydrolysis of mildly crosslinked (fixed) protein(-RNA) complexes on EM grids
In collaboration with the Cryo-EM group from Holger Stark we are developing methods that allow analysing protein complexes by mass spectrometry that are attached on carbon grids for electron microscopy analysis. In this manner not only the protein composition of those particles that are visible in the EM can be determined by LC-MSMS but also interacting protein regions of the complexes. The latter is due to the mild fixation of the particles prior to carbon film attachment. The mild fixation with e.g. glutaraldehyd (Link) leaves protected (e.g. interacting) regions of protein components unmodified so that they can be identified in a database search subsequent to hydrolysis and LC-MSMS analysis of the particles.