We use a combination of experimental gas phase techniques, molecular modelling and solution chemistry methods to interrogate conformations of proteins, peptides and other molecular species. The Barran group has considerable experience in gas-phase ion chemistry and the application of mass spectrometry to complex chemical and biological problems.

We are interested in developing instrumentation, and aim to be system rather than technique led. A particular interest is to probe conformational changes that occur as an indicator of biological activity, for example [Ca]²⁺ binding to Calmodulin, defensins binding to saccharides, or cyclosporin binding to cyclophillin.

We have developed ion mobility mass spectrometry as a tool to investigate changes in protein and peptide conformation. This work is supported by molecular mechanics based calculations which supply candidate geometries to compare with those measured.

Some of our work is based on interrogating model systems, as we seek a general understanding of biological processes. However, strong collaborations with biological chemists and medical researchers, enable us to also examine 'real world' problems.

In collaboration with Waters UK, we have developed new instrumentation and techniques to investigate changes in protein conformation that occur in response to chemical or physical intervention. We also utilise computational tools, principally molecular mechanics, to evaluate protein and peptide structure.

We are currently collaborating with Dr. Cait MacPhee (University of Edinburgh) to look at pre-fibrular amyloid aggregates with ion mobility mass spectrometry (IM-MS). This work has recently been supported by a BBSRC award. We also have an ongoing collaboration with Dr. Helen Cooper (U of Birmingham) to use both ECD and IM-MS to understand the structure dissociation behaviour of model poly peptides. Along with Professor Ted Hupp, and Dr. Penka Nicolova we have investigated the conformational flexibility of the protein p53 using mass spectrometry and IM-MS. With Paul Barlow, we have examined several connected modules of the complement control protein factor H. Analogous to findings from other biophysical methods on this system we have observed considerable conformational flexibility, exemplified in mass spectrometry by a broad charge state distribution even under native spray conditions and in cross section space by a wide range of conformations observe. With Dek Woolfson (University of Bristol) we are examining synthetic switching peptides with IM-MS. We also are involved in a number of proteomic investigations, with the broad aim of establishing patterns produced by disease states for early stage diagnosis.

We are not limited to gas-phase techniques, and have recently been exploring HD exchange methodologies to determine solution conformations for comparison with those derived in the gas-phase. Deuterium is used to probe the solvent exposed portions of the protein/or complex, and mass spectrometry to report on this via mass increase measurements.. In the main the Barran Group works with biological and biomedical groups who provide both interesting problems and the background in the systems to help understand and exploit what we observe.

SELECTED RECENT PUBLICATIONS

1. McCullough, B. J.; Kalapothakis, J. M.; Chin, W.; Taylor, K.; Clarke, D. J.; Eastwood, H.; Campopiano, D.; MacMillan, D.; Dorin, J.; Barran, P. E. Physical Chemistry Chemical Physics 2010, 12, 3589-3596.
2. De Cecco, M.; Seo, E. S.; Clarke, D. J.; McCullough, B. J.; Taylor, K.; Macmillan, D.; Dorin, J. R.; Campopiano, D. J.; Barran, P. E. Journal of Physical Chemistry B 2010, 114, 2312-2318
3. Shirran, S. L.; Barran, P. E. Journal of the American Society for Mass Spectrometry 2009, 20, 1159-1171.
4. McCullough, B. J.; Kalapothakis, J.; Eastwood, H.; Kemper, P.; MacMillan, D.; Taylor, K.; Dorin, J.; Barran, P. E. Analytical Chemistry 2008, 80, 6336-6344

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