Abstract

In recent years LILBID mass spectrometry has been shown to have great potential for the investigation of biomolecules and biomolecular complexes that have proven challenging to investigate by more standardly used methods. The ionization method is soft, sensitive and tolerant against solution additions, allowing for the investigation of many different kinds of non-covalently bound complexes including soluble or membrane proteins as well as RNA /DNA.

For LILBID -MS micro droplets (30μm diameter) of the aqueous analyte solution are generated by a droplet generator at a frequency of 10Hz and transferred to vacuum. There the droplets are irradiated by an infrared laser pulse, which deposits its energy into the OH stretching vibrations of the water molecules. This leads to the explosive expansion of the droplets, setting the solvated ions free, which can then be analysed. Via the laser energy deposited into the droplet the degree of complex dissociation can be controlled allowing for the investigation of intact non-covalently bound protein complexes or their building blocks.

I will give an overview over recent progress in different areas. We can investigate challenging soluble proteins, as the Alzheimer triggering Aß42 peptide, for which LILBID allows to follow the aggregation process for Oligomers up to 20mers. We have as well analysed large membrane protein complexes such as ATPases from detergent micelles. I will introduce the developments allowing for the investigation of membrane complexes from nanodiscs, which mimic the proteins native surrounding of the membrane, where detergent micelles can’t be used satisfactorily. Using this method we could for example shed light on the process which leads in cell free expression systems to the integration of the proteins into the nanodiscs.