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Toward increased concentration sensitivity for continuous wave EPR investigations of spin-labeled biological macromolecules at high fields
- Source :
- Journal of Magnetic Resonance. 265:188-196
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- This work was performed at the National High Magnetic Field Laboratory (NHMFL), which is supported by the National Science Foundation (DMR-1157490) and the State of Florida. L.S. acknowledges support from the National Institutes of Health (AI091693) and the NHMFL User Collaboration Grants Program (Award No. 5080). G.E.F. acknowledges support from the National Science Foundation (MCB-1329467) and the National Institutes of Health (GM105409 and S10RR031603). S.H. acknowledges support from the National Science Foundation (DMR-1309463). J.M.E acknowledges support from the National Science Foundation (DGE-0802270). High-field, high-frequency electron paramagnetic resonance (EPR) spectroscopy at W- (∼95 GHz) and D-band (∼140 GHz) is important for investigating the conformational dynamics of flexible biological macromolecules because this frequency range has increased spectral sensitivity to nitroxide motion over the 100 ps to 2 ns regime. However, low concentration sensitivity remains a roadblock for studying aqueous samples at high magnetic fields. Here, we examine the sensitivity of a non-resonant thin-layer cylindrical sample holder, coupled to a quasi-optical induction-mode W-band EPR spectrometer (HiPER), for continuous wave (CW) EPR analyses of: (i) the aqueous nitroxide standard, TEMPO; (ii) the unstructured to α-helical transition of a model IDP protein; and (iii) the base-stacking transition in a kink-turn motif of a large 232 nt RNA. For sample volumes of ∼50 μL, concentration sensitivities of 2-20 μM were achieved, representing a ∼10-fold enhancement compared to a cylindrical TE011 resonator on a commercial Bruker W-band spectrometer. These results therefore highlight the sensitivity of the thin-layer sample holders employed in HiPER for spin-labeling studies of biological macromolecules at high fields, where applications can extend to other systems that are facilitated by the modest sample volumes and ease of sample loading and geometry. Postprint
- Subjects :
- Spin label
0301 basic medicine
Nuclear and High Energy Physics
Nitroxide mediated radical polymerization
Macromolecular Substances
Glycine
NDAS
Biophysics
Analytical chemistry
IDP
010402 general chemistry
01 natural sciences
Biochemistry
law.invention
03 medical and health sciences
Electromagnetic Fields
law
High field
Electron paramagnetic resonance
Spectroscopy
Vibrio cholerae
QC
Spectrometer
Chemistry
Electron Spin Resonance Spectroscopy
Proteins
Reproducibility of Results
Condensed Matter Physics
0104 chemical sciences
RNA, Bacterial
QC Physics
030104 developmental biology
Spectral sensitivity
RNA
Continuous wave
Spin Labels
EPR
Algorithms
Macromolecule
Subjects
Details
- ISSN :
- 10907807
- Volume :
- 265
- Database :
- OpenAIRE
- Journal :
- Journal of Magnetic Resonance
- Accession number :
- edsair.doi.dedup.....fc65f08f02e49f1ca0a4f583fd48a6cc