| Autor: |
H. EL Mkami, R. I. Hunter, P. A. S. Cruickshank, M. J. Taylor, J. E. Lovett, A. Feintuch, M. Qi, A. Godt, G. M. Smith |
| Jazyk: |
angličtina |
| Rok vydání: |
2020 |
| Předmět: |
|
| Zdroj: |
Magnetic Resonance, Vol 1, Pp 301-313 (2020) |
| Druh dokumentu: |
article |
| ISSN: |
2699-0016 |
| DOI: |
10.5194/mr-1-301-2020 |
| Popis: |
Gadolinium complexes are attracting increasing attention as spin labels for EPR dipolar distance measurements in biomolecules and particularly for in-cell measurements. It has been shown that flip-flop transitions within the central transition of the high-spin Gd3+ ion can introduce artefacts in dipolar distance measurements, particularly when measuring distances less than 3 nm. Previous work has shown some reduction of these artefacts through increasing the frequency separation between the two frequencies required for the double electron–electron resonance (DEER) experiment. Here we use a high-power (1 kW), wideband, non-resonant system operating at 94 GHz to evaluate DEER measurement protocols using two stiff Gd(III) rulers, consisting of two bis-Gd3+–PyMTA complexes, with separations of 2.1 nm and 6.0 nm, respectively. We show that by avoiding the -12→12 central transition completely, and placing both the pump and the observer pulses on either side of the central transition, we can now observe apparently artefact-free spectra and narrow distance distributions, even for a Gd–Gd distance of 2.1 nm. Importantly we still maintain excellent signal-to-noise ratio and relatively high modulation depths. These results have implications for in-cell EPR measurements at naturally occurring biomolecule concentrations. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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