4.3 Article

Enhancing sensitivity of Double Electron-Electron Resonance (DEER) by using Relaxation-Optimized Acquisition Length Distribution (RELOAD) scheme

Journal

JOURNAL OF MAGNETIC RESONANCE
Volume 298, Issue -, Pages 115-126

Publisher

ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jmr.2018.12.004

Keywords

PELDOR; DEER; EPR; Spin-labeling; Dipolar spectroscopy; Distance measurements

Funding

  1. U.S. Department of Energy Basic Biosciences Program (DOE) [DE-FG02-02ER15354]
  2. National Institutes of Health [RR023614]
  3. National Science Foundation [CHE-0840501]
  4. North Carolina Biotechnology Center (NCBC) [2009-IDG-1015]
  5. NSF [CBET-1403871]
  6. National Key Research and Development Program of the Ministry of Science and Technology of the People's Republic of China [2016YFA0501203]
  7. National Natural Science Foundation of China [31470727, 21874004]
  8. interdisciplinary medicine Seed Fund of Peking University
  9. Beijing National Laboratory for Molecular Sciences, People's Republic of China

Ask authors/readers for more resources

Over the past decades pulsed electron-electron double resonance (PELDOR), often called double electron electron resonance (DEER), became one of the major spectroscopic tools for measurements of nanometer-scale distances and distance distributions in non-crystalline biological and chemical systems. The method is based on detecting the amplitude of the primary (3-pulse DEER) or refocused (4-pulse DEER) spin echo for the so-called observer spins when the other spins coupled to the former by a dipolar interaction are flipped by a pump pulse at another EPR frequency. While the timing of the pump pulse is varied in steps, the positions of the observer pulses are typically fixed. For such a detection scheme the total length of the observer pulse train and the electron spin memory time determine the amplitude of the detected echo signal. Usually, the distance range considerations in DEER experiments dictate the total length of the observer pulse train to exceed the phase memory time by a factor of few and this leads to a dramatic loss of the signal-to-noise ratio (SNR). While the acquisition of the DEER signal seems to be irrational under such conditions, it is currently the preferred way to conduct DEER because of an effective filtering out of all other unwanted interactions. Here we propose a novel albeit simple approach to improve DEER sensitivity and decrease data acquisition time by introducing the signal acquisition scheme based on RELaxation Optimized Acquisition (Length) Distribution (DEER-RELOAD). In DEER-RELOAD the dipolar phase evolution signal is acquired in multiple segments in which the observer pulses are fixed at the positions to optimize SNR just for that specific segment. The length of the segment is chosen to maximize the signal acquisition efficiency according the phase relaxation properties of the spin system. The total DEER trace is then obtained by stitching the multiple segments into a one continuous trace. The utility of the DEER-RELOAD acquisition scheme has been demonstrated on an example of the standard 4-pulse DEER sequence applied to two membrane protein complexes labeled with nitroxides. While theoretical gains from the DEER-RELOAD scheme increase with the number of stitched segments, in practice, even dividing the acquisition of the DEER trace into two segments may improve SNR by a factor of >3, as it has been demonstrated for one of these two membrane proteins. (C) 2018 Elsevier Inc. All rights reserved.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.3
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available