Source:http://linkedlifedata.com/resource/pubmed/id/20684534
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
45
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| pubmed:dateCreated |
2010-11-12
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| pubmed:abstractText |
Blue-light excitation of cryptochromes and homologues uniformly triggers electron transfer (ET) from the protein surface to the flavin adenine dinucleotide (FAD) cofactor. A cascade of three conserved tryptophan residues has been considered to be critically involved in this photoreaction. If the FAD is initially in its fully oxidized (diamagnetic) redox state, light-induced ET via the tryptophan triad generates a series of short-lived spin-correlated radical pairs comprising an FAD radical and a tryptophan radical. Coupled doublet-pair species of this type have been proposed as the basis, for example, of a biological magnetic compass in migratory birds, and were found critical for some cryptochrome functions in vivo. In this contribution, a cryptochrome-like protein (CRYD) derived from Xenopus laevis has been examined as a representative system. The terminal radical-pair state FAD(•)···W324(•) of X. laevis CRYD has been characterized in detail by time-resolved electron-paramagnetic resonance (TREPR) at X-band microwave frequency (9.68 GHz) and magnetic fields around 345 mT, and at Q-band (34.08 GHz) at around 1215 mT. Different precursor states, singlet versus triplet, of radical-pair formation have been considered in spectral simulations of the experimental electron-spin polarized TREPR signals. Conclusively, we present evidence for a singlet-state precursor of FAD(•)···W324(•) radical-pair generation because at both magnetic fields, where radical pairs were studied by TREPR, net-zero electron-spin polarization has been detected. Neither a spin-polarized triplet precursor nor a triplet at thermal equilibrium can explain such an electron-spin polarization. It turns out that a two-microwave-frequency TREPR approach is essential to draw conclusions on the nature of the precursor electronic states in light-induced spin-correlated radical pair formations.
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| pubmed:grant | |
| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical | |
| pubmed:status |
MEDLINE
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| pubmed:month |
Nov
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| pubmed:issn |
1520-5207
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| pubmed:author |
pubmed-author:BertholdThomasT,
pubmed-author:BiskupTillT,
pubmed-author:GetzoffElizabeth DED,
pubmed-author:HitomiKenichiK,
pubmed-author:LinkGerhardG,
pubmed-author:MarinoAnthony RAR,
pubmed-author:NorrisJames RJRJr,
pubmed-author:OkafujiAsakoA,
pubmed-author:SchleicherErikE,
pubmed-author:WeberStefanS
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| pubmed:issnType |
Electronic
|
| pubmed:day |
18
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| pubmed:volume |
114
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
14745-54
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| pubmed:meshHeading |
pubmed-meshheading:20684534-Animals,
pubmed-meshheading:20684534-Cryptochromes,
pubmed-meshheading:20684534-Electron Spin Resonance Spectroscopy,
pubmed-meshheading:20684534-Electron Transport,
pubmed-meshheading:20684534-Flavin-Adenine Dinucleotide,
pubmed-meshheading:20684534-Free Radicals,
pubmed-meshheading:20684534-Light,
pubmed-meshheading:20684534-Models, Molecular,
pubmed-meshheading:20684534-Protein Conformation,
pubmed-meshheading:20684534-Xenopus Proteins,
pubmed-meshheading:20684534-Xenopus laevis
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| pubmed:year |
2010
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| pubmed:articleTitle |
Origin of light-induced spin-correlated radical pairs in cryptochrome.
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| pubmed:affiliation |
Institute of Physical Chemistry, Albert-Ludwigs-Universita?t Freiburg, 79104 Freiburg, Germany. Stefan.Weber@physchem.uni-freiburg.de
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| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, Non-U.S. Gov't,
Research Support, N.I.H., Extramural
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