Dr Jackie A. Mosely
(email at email@example.com)
Mass spectrometry is a very powerful analytical tool. Sheer versatility and sensitivity have enabled the use of this technique in a wide range of applications. Our research is based on pushing the boundaries of mass spectrometry within many life science applications, currently focusing on small molecule characterisation, protein identification, lipid analyses and synthetic polymer analysis to name but a very few. We collaborate widely with both industry and various UK academic laboratories during the course of our studies.
Durham University Chemistry Department is very well equipped with a range of high performance mass spectrometers. The latest MS technology, a Synapt G2s, incorporates Ion Mobility Separation (IMS) as well as CID and ETD tandem capabilities. A hybrid 7T LC FTICR MS provides the ultimate level of performance achieving sub ppm mass accuracy and a resolving power greater than 500,000 FWHH. New developments in API technology, the innovative Atmospheric Pressure GC (APGC) ion source and Atmospheric Solids Analysis Probe (ASAP), are available on a QToF MS. Other LCMS instruments include ESI-QToF MS, ESI-ToF MS and ESI-QqQ MS, thus complementing traditional GC EI/CI-MS. MALDI-ToF/ToF MS is also available and provide additional and complementary information.
Novel ionisation techniques
The ASAP probe is capable of analysing both solid samples and solutions and has successfully analysed a wide range of chemical compounds including insoluble or partially soluble chemicals traditionally studied by probe EI, organometallic species that have previously been the remit of FAB/LSIMS, or more recently MALDI, and boron containing compounds that were historically analysed by MALDI or ESI.
In addition, a GC connected directly to the APGC ion source has shown unique flexibility in generating either protonated ions or radical cations at the operators’ discretion which in can provide ‘tuneable’ product ion spectra.
Figure 1 shows an APGC spectrum of the compound C17H18NOI. (a) By keeping the ion chamber relatively dry, the radical cation is observed along side a few other molecular ions. (b) Subsequent tandem MS reveals a large number of intense product ions that are comparable to traditional EI data. (c) In comparison, spraying methanol into the ion chamber pushes ionisation towards 100 % protonated molecular ion, generating a nice clean MS spectrum, however the protonated adduct fragments to give far less product ion information (d).
Tandem Mass Spectromtry: Electron Capture Dissociation
The FTICR MS at Durham was upgraded to facilitate electron capture dissociation (ECD). This technique has been used successfully to characterise some exciting lanthanide metal complexes then to sequence phosphorylated peptides modified by the lanthanide metal complexes3. This work is in collaboration with Professor David Parker (Durham University) and will pave the way to developing affinity based chromatographic materials and bio-imaging probes for NMR and MS assays.
Figure 2 shows electron capture dissociation mass spectrum of TRDIYETDY*YRK modified at the phosphorylated residue, Y*, by a Europium macrocyclic complex. The peptide backbone is systematically cleaved at the alpha-carbon atoms up to the modified residue with charge retained by the N-terminal fragments (identified as c-ions) or the charge retained by the C-terminal fragments (identified as z+1 ions due to an additional hydrogen). Location of the intact modification is clearly identified.
Our investigation into the technique ECD has expanded into the world of small molecules where we have shown that a related technique, EID (Electron Induced Dissociation), can be used to aid structural identification of pharmaceutical type compounds1,2. These hot electrons have also been of benefit in the structural characterisation of synthetic glycopolymers of the type developed at Durham by Prof. Neil Cameron’s research group, providing complimentary information to traditional tandem MS techniques.
FTICR MS and MALDI TOF MS have been used for the analysis of membrane proteins7 and their interactions with small molecules. Particular focus lay in the molecular consequences of such interactions in the form of resulting peptide/protein modifications, most recently investigating acylation of a peptide following incubation with a phospholipid4,5,6.
- Aruna S. Prakash, Michael J. P. Smith, Zied Kaabia, Glenn Hurst, Ci Yan, Martin Sims, Anthony T. W. Bristow, Peter Stokes, David Parkerand Jackie A. Mosely; J. Am. Soc. Mass Spectrom., 2012, 23, 850-857.
- Jackie A. Mosely, Michael J. P. Smith, Aruna S. Prakash, Martin Sims, Anthony T. W. Bristow; Anal Chem., 2011, 83, 4068-4075.
- J. A. Mosely, B. S. Murrayand D. Parker; Eur. J. Mass Spectrom., 2009, 15, 145.
- Robert H. Dods, Burkhard Bechinger, Jackie A. Mosely and John M. Sanderson.; J. Mol. Bio., 2013, 425, 4379-4387.
- Robert H Dods, Jackie A Mosely and John M Sanderson; Org. Biomol. Chem., 2012, 10, 5371-5378.
- Catherine J. Pridmore, Jackie A. Mosely, Alison Rodger and John M. Sanderson; Chem. Commun., 2011, 45, 1422-1424.
- V. A. Money, H. K. McPhee, J. A. Mosely, J. M. Sanderson and R. P. Yeo, Proc. Natl. Acad. Sci., 2009, 106, 4441-4446.
- Ball, Andrew T., Prakash, Aruna S., Bristow, Anthony W. T., Sims, Martin & Mosely, Jackie A. (2016). Characterisation of phosphorylated nucleotides by collisional and electron-based tandem mass spectrometry. Rapid Communications in Mass Spectrometry 30(19): 2155-2163.