Research areas

Gentle application of nano electrospray to proteins buffered in solution to an appropriate pH allows us to use mass spectrometry to interrogate the gas phase version of their solution conformations. This can be achieved directly with ion mobility mass spectrometry, where we measure the rotationally averaged temperature dependent collision cross section of mass separated ions, or more indirectly with the use of dissociation methods and/or HDX.

Data obtained from both methods provides insight to the structure and stability of the protein, and also detail on its interactions, especially when combined with atomistically resolved data from crystallography and or computational approaches. DT IM-MS is our central technique and one that we are currently developing a new higher resolution instrument for, however we employ several other biophysical methodologies.

CCS vs. MassThe diagram presents variety of molecules that have been analysed on our linear drift tube ion mobility mass spectrometer ‘The MoQTOF’ as of early 2013.  We have determined collision cross sections (CCSs) for systems ranging from molecular knots, supramolecular cages, though variety of peptides and monomeric proteins up to large protein complexes such as antibodies (~150 kDa) and human SAP (~250 kDa).

Systems

The majority of mass spectrometry analysis of biological systems is focussed on analysis of primary structure. This powerful ‘bottom-up’ approach has reaped vast benefits in post-genomic science, in particular in quantification and in locating post-translational modifications. This area of research has not much been influenced by any desire to understand conformation, and indeed most methodologies …

Techniques

We employ a number of characterisation techniques; most analysis is conducted in the gas phase, where we take care to gently introduce our samples from solution. We also use solution and solid phase analysis to complement our in vacuo findings Ion Mobility Mass Spectrometry is our main technique – further information on this can be …

Instruments

We have a number of mass spectrometers in our group, three of which have been modified in-house. All are quadrupole time of flight mass spectrometers. Ion Mobility Capable Q-ToF – ‘The MoqToF’ This instrument was developed in our group by Bryan McCullough in collaboration with Dr Paul Kemper (UCSB) and Micromass  Ltd (Manchester, UK). It …