Poster Presentation 23rd International Society of Magnetic Resonance Conference 2023

Expanding the capabilities of benchtop EPR systems (#311)

Paige M.E. Hawkins 1 , BISWARANJAN MOHANTY 1 , Philip W. Kuchel 2 , Ian Luck 1
  1. Sydney Analytical, The University of Sydney, Sydney, NSW, Australia
  2. School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia

Electron paramagnetic resonance (EPR) is a highly valuable non-destructive technique for elucidating structural and dynamic information in chemical, physical and biological systems. However, its utility is restricted in many labs due to the high infrastructure cost. As such, benchtop systems like the Bruker EMX Nano, have applicability as a low-cost solution. In this poster we will demonstrate the wide range of functionalities that we have been able to achieve using the Bruker EMX Nano.

Variable-temperature EPR to investigate diffusion: Slow rotational diffusion of EPR-active molecules is known to lead to an incomplete averaging of the EPR spectrum, resulting in an asymmetrical spectrum. This spectrum can then be interpreted to extract solute-solvent specific parameters i.e. rotational and translational diffusion and solvent viscosity.1 In our hands, we have demonstrated this asymmetry through use of the molecular probe 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL) by conducting EPR measurements at a range of temperatures.

In-situ irradiation and 2D time-dependent EPR measurements for the study of antioxidants: Vitamin E consists of a group of eight structurally related, fat-soluble antioxidants, which due to these properties, have also been utilised as stabilisers and antioxidants in consumer goods, preventing discolouration and preserving product freshness. We have exploited our benchtop EPR system to investigate the life-time of the tocopheroxyl radical in various cooking oils under ultraviolet light.2 The tocopheroxyl radicals generated under UV light rapidly decay via dimerization processes and hence, the use of in-situ EPR measurements is vital for this study.

EPR to elucidate binding affinity: The chelation of Mn2+ or Mg2+ to isocitrate is a key step in the enzymatically catalysed and NAD+-mediated decarboxylation of isocitrate. The stability of Mn2+ and Mg2+ complexes of isocitrate were compared in a competitive binding experiment, as monitored via EPR to measure free Mn2+ in ligand-metal-ion solutions.3

  1. [1] Evans, R. G.; Wain, A. J.; Hardacre, C.; Compton, R. G., ChemPhysChem, 2005, 6, (6), 1035-1039.
  2. [2] Kagan, V.; Witt, E.; Goldman, R.; Scita, G.; Packer, L. Free Rad. Res. Comms., 1992, 16, (1), 51-64.
  3. [3] Kuchel, P. W.; Reynolds, C. H.; Dalziel, K., Eur. J. Biochem., 1980, 110, (2), 465-473.