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Light‐Induced Pulsed EPR Dipolar Spectroscopy on a Paradigmatic Hemeprotein
Author(s) -
Dal Farra Maria Giulia,
Richert Sabine,
Martin Caterina,
Larminie Charles,
Gobbo Marina,
Bergantino Elisabetta,
Timmel Christiane R.,
Bowen Alice M.,
Di Valentin Marilena
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201900139
Subject(s) - chemistry , electron paramagnetic resonance , spectroscopy , neuroglobin , myoglobin , dipole , hemeprotein , chromophore , pulsed epr , triplet state , nuclear magnetic resonance , photochemistry , molecular physics , chemical physics , heme , molecule , physics , globin , spin echo , hemoglobin , medicine , biochemistry , organic chemistry , quantum mechanics , magnetic resonance imaging , radiology , enzyme
Abstract Light‐induced pulsed EPR dipolar spectroscopic methods allow the determination of nanometer distances between paramagnetic sites. Here we employ orthogonal spin labels, a chromophore triplet state and a stable radical, to carry out distance measurements in singly nitroxide‐labeled human neuroglobin. We demonstrate that Zn‐substitution of neuroglobin, to populate the Zn(II) protoporphyrin IX triplet state, makes it possible to perform light‐induced pulsed dipolar experiments on hemeproteins, extending the use of light‐induced dipolar spectroscopy to this large class of metalloproteins. The versatility of the method is ensured by the employment of different techniques: relaxation‐induced dipolar modulation enhancement (RIDME) is applied for the first time to the photoexcited triplet state. In addition, an alternative pulse scheme for laser‐induced magnetic dipole (LaserIMD) spectroscopy, based on the refocused‐echo detection sequence, is proposed for accurate zero‐time determination and reliable distance analysis.