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Porphyrin Triplet State as a Potential Spin Label for Nanometer Distance Measurements by PELDOR Spectroscopy
journal contribution
posted on 2014-05-07, 00:00 authored by Marilena Di Valentin, Marco Albertini, Enrico Zurlo, Marina Gobbo, Donatella CarboneraThis 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.