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Updated: May 20, 2026

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
Published on: July 4, 2016
Monitoring structural transitions in IDPs by site-directed spin labeling EPR spectroscopy
Johnny Habchi1, Marlène Martinho, Antoine Gruet
1Architecture et Fonction des Macromolécules Biologiques, UMR 7257 CNRS and Aix-Marseille Université, Marseille, France.
Abstract:
Electron paramagnetic resonance (EPR) spectroscopy is a technique that specifically detects unpaired electrons. EPR sensitive reporter groups (spin labels or spin probes) can be introduced into biological systems via site-directed spin labeling (SDSL). This is usually accomplished by cysteine-substitution mutagenesis followed by covalent modification of the unique sulfhydryl group with a selective nitroxide reagent. SDSL EPR spectroscopy has been shown to be a sensitive and powerful method to study structural transitions within intrinsically disordered proteins (IDPs). In this chapter, we provide a detailed experimental protocol for this approach and present a few examples of EPR spectral shapes illustrative of various mobility regimes of the spin probe, reflecting different protein topologies.
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