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Updated: Jul 19, 2026

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
Published on: July 4, 2016
Comparison of electron paramagnetic resonance methods to determine distances between spin labels on human carbonic
M Persson1, J R Harbridge, P Hammarström
1Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA.
Abstract:
Four doubly spin-labeled variants of human carbonic anhydrase II and corresponding singly labeled variants were prepared by site-directed spin labeling. The distances between the spin labels were obtained from continuous-wave electron paramagnetic resonance spectra by analysis of the relative intensity of the half-field transition, Fourier deconvolution of line-shape broadening, and computer simulation of line-shape changes. Distances also were determined by four-pulse double electron-electron resonance. For each variant, at least two methods were applicable and reasonable agreement between methods was obtained. Distances ranged from 7 to 24 A. The doubly spin-labeled samples contained some singly labeled protein due to incomplete labeling. The sensitivity of each of the distance determination methods to the non-interacting component was compared.
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