Significantly improved sensitivity of Q-band PELDOR/DEER experiments relative to X-band is observed in measuring the intercoil distance of a leucine zipper motif peptide (GCN4-LZ)

Biochemistry. 2009 Jun 30;48(25):5782-4. doi: 10.1021/bi900781u.

Abstract

Pulsed electron double resonance (PELDOR)/double electron-electron resonance (DEER) spectroscopy is a very powerful structural biology tool in which the dipolar coupling between two unpaired electron spins (site-directed nitroxide spin-labels) is measured. These measurements are typically conducted at X-band (9.4 GHz) microwave excitation using the four-pulse DEER sequence and can often require up to 12 h of signal averaging for biological samples (depending on the spin-label concentration). In this work, we present for the first time a substantial increase in DEER sensitivity obtained by collecting DEER spectra at Q-band (34 GHz), when compared to X-band. The huge boost in sensitivity (factor of 13) demonstrated at Q-band represents a 169-fold decrease in data collection time, reveals a greatly improved frequency spectrum and higher-quality distance data, and significantly increases sample throughput. Thus, the availability of Q-band DEER spectroscopy should have a major impact on structural biology studies using site-directed spin labeling EPR techniques.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Motifs
  • Basic-Leucine Zipper Transcription Factors / analysis
  • Basic-Leucine Zipper Transcription Factors / chemistry*
  • Electron Spin Resonance Spectroscopy / methods*
  • Electron Spin Resonance Spectroscopy / standards
  • Leucine Zippers*
  • Peptide Fragments / analysis
  • Peptide Fragments / chemistry*
  • Saccharomyces cerevisiae Proteins / analysis
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Spin Trapping / methods

Substances

  • Basic-Leucine Zipper Transcription Factors
  • GCN4 protein, S cerevisiae
  • Peptide Fragments
  • Saccharomyces cerevisiae Proteins