Exploiting orientation-selective DEER: determining molecular structure in systems containing Cu(II) centres

Alice M. Bowen, Michael W. Jones, Janet E. Lovett, Thembanikosi G. Gaule, Michael J. McPherson, Jonathan R. Dilworth, Christiane R. Timmel*, Jeffrey R. Harmer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Orientation-selective DEER (Double Electron-Electron Resonance) measurements were conducted on a series of rigid and flexible molecules containing Cu(ii) ions. A system with two rigidly held Cu(ii) ions was afforded by the protein homo-dimer of copper amine oxidase from Arthrobacter globiformis. This system provided experimental DEER data between two Cu(ii) ions with a well-defined distance and relative orientation to assess the accuracy of the methodology. Evaluation of orientation-selective DEER (os DEER) on systems with limited flexibility was probed using a series of porphyrin-based Cu(ii)-nitroxide and Cu(ii)-Cu(ii) model systems of well-defined lengths synthesized for this project. Density functional theory was employed to generate molecular models of the conformers for each porphyrin-based Cu(ii) dimer studied. Excellent agreement was found between DEER traces simulated using these computed conformers and the experimental data. The performance of different parameterised structural models in simulating the experimental DEER data was also investigated. The results of this analysis demonstrate the degree to which the DEER data define the relative orientation of the two Cu(ii) ions and highlight the need to choose a parameterised model that captures the essential features of the flexibility (rotational freedom) of the system being studied.

Original languageEnglish
Pages (from-to)5981-5994
Number of pages14
JournalPhysical Chemistry Chemical Physics
Volume18
Issue number8
Early online date3 Feb 2016
DOIs
Publication statusPublished - 28 Feb 2016

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