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Electron Spin Relaxation of Photoexcited Porphyrin in Water-Glycerol Glass Full article

Journal Molecules
, E-ISSN: 1420-3049
Output data Year: 2020, Volume: 25, Number: 11, DOI: 10.3390/molecules25112677
Tags DEER/PELDOR; distance measurements; electron spin relaxation; EPR spectroscopy; porphyrin; spin labels
Authors Sannikova N. 1 , Timofeev I. 1 , Bagryanskaya E. 2 , Bowman M. 2,3 , Fedin M. 1 , Krumkacheva O. 1
Affiliations
1 (Scopus) International Tomography Center SB RAS, Novosibirsk, 630090, Russian Federation
2 (Scopus) N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russian Federation
3 (Scopus) Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, AL 35487-0336, USA

Abstract: Recently, the photoexcited triplet state of porphyrin was proposed as a promising spin-label for pulsed dipolar electron paramagnetic resonance (EPR). Herein, we report the factors that determine the electron spin echo dephasing of the photoexcited porphyrin in a water-glycerol matrix. The electron spin relaxation of a water-soluble porphyrin was measured by Q-band EPR, and the temperature dependence and the effect of solvent deuteration on the relaxation times were studied. The phase memory relaxation rate (1/Tm) is noticeably affected by solvent nuclei and is substantially faster in protonated solvents than in deuterated solvents. The Tm is as large as 13-17 μs in deuterated solvent, potentially expanding the range of distances available for measurement by dipole spectroscopy with photoexcited porphyrin. The 1/Tm depends linearly on the degree of solvent deuteration and can be used to probe the environment of a porphyrin in or near a biopolymer, including the solvent accessibility of porphyrins used in photodynamic therapy. We characterized the noncovalent binding of porphyrin to human serum albumin (HSA) from 1/Tm and electron spin echo envelope modulation (ESEEM) and found that porphyrin is quite exposed to solvent on the surface of HSA. The 1/Tm and ESEEM are equally effective and provide complementary methods to determine the solvent accessibility of a porphyrin bound to protein or to determine the location of the porphyrin.
Cite: Sannikova N. , Timofeev I. , Bagryanskaya E. , Bowman M. , Fedin M. , Krumkacheva O.
Electron Spin Relaxation of Photoexcited Porphyrin in Water-Glycerol Glass
Molecules. 2020. V.25. N11. DOI: 10.3390/molecules25112677 WOS Scopus OpenAlex
Files: Full text from publisher
Dates:
Published online: Jun 9, 2020
Identifiers:
Web of science: WOS:000553858800214
Scopus: 2-s2.0-85086424057
OpenAlex: W3034828489
Citing:
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Scopus 7
Web of science 7
OpenAlex 7
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