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Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
Published on: July 4, 2016
Porphyrin triplet state as a potential spin label for nanometer distance measurements by PELDOR spectroscopy
Marilena Di Valentin1, Marco Albertini, Enrico Zurlo
1Dipartimento di Scienze Chimiche, Università di Padova , via Marzolo 1, 35131 Padova, Italy.
Abstract:
This work demonstrates, for the first time, the feasibility of applying pulsed electron-electron double resonance (PELDOR/DEER) to determine the interspin distance between a photoexcited porphyrin triplet state (S = 1) and a nitroxide spin label chemically incorporated into a small helical peptide. The PELDOR trace shows deep envelope modulation induced by electron-electron dipole interaction between the partners in the pair, providing an accurate distance measurement. This new labeling approach has a high potential for measuring nanometer distances in more complex biological systems due to the sensitivity acquired from the spin polarization of the photoexcited triplet state spectrum.
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