In:
Physical Chemistry Chemical Physics, Royal Society of Chemistry (RSC), Vol. 24, No. 20 ( 2022), p. 12528-12540
Abstract:
Electron paramagnetic resonance (EPR) experiments for protein structure determination using double electron–electron resonance (DEER) spectroscopy rely on high-power microwave amplifiers ( 〉 300 W) to create the short pulse lengths needed to excite a sizable portion of the spectrum. The recently introduced self-resonant microhelix combines a high B 1 conversion efficiency with an intrinsically large bandwidth (low Q -value) and a high absolute sensitivity. We report dead times in 3-pulse DEER experiments as low as 14 ± 2 ns achieved using less than 1 W of power at X-band (nominally 9.5 GHz) for experiments on a molecular ruler and a T4 lysozyme sample for concentrations down to 100 μM. These low-power experiments were performed using an active volume 120 times smaller than that of a standard pulse EPR resonator, while only a 11-fold decrease in the signal-to-noise ratio was observed. Small build sizes, as realized with the microhelix, give access to volume-limited samples, while shorter dead times allow the investigation of fast relaxing spin species. With the significantly reduced dead times, the 3-pulse DEER experiment can be revisited. Here, we show experimentally that 3-pulse DEER offers superior sensitivity over 4-pulse DEER. We assert that the microhelix paves the road for low-cost benchtop X-band pulse EPR spectrometers by eliminating the need for high-power amplifiers, accelerating the adoption of pulse EPR to a broader community.
Type of Medium:
Online Resource
ISSN:
1463-9076
,
1463-9084
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
1476283-3
detail.hit.zdb_id:
1476244-4
detail.hit.zdb_id:
1460656-2
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