Noell, Gilbert and Hauska, Gunter and Hegemann, Peter and Lanzl, Karin and Noell, Tanja and von Sanden-Flohe, Madlene and Dick, Bernhard (2007) Redox properties of LOV domains: Chemical versus photochemical reduction, and influence on the photocycle. CHEMBIOCHEM, 8 (18). pp. 2256-2264. ISSN 1439-4227,
Full text not available from this repository. (Request a copy)Abstract
LOV (light-oxygen-voltoge-sensitive) domains comprise the lightsensitive parts of many blue light photoreceptor proteins. Photoexcitation of the chromophore flavin mononucleotide (FMN) in these LOV domains leads to formation of a covalent adduct between FMN and a cysteine residue. So for, the electronically excited singlet and triplet states of FMN have been identified as the only intermediates in the photocycles of LOV domains from several organisms. Since many flavoproteins ore redox-active, however, the photocycles of LOV domains might involve other redox states of FMN, and might be controlled by the external redox potential. Here we report on the redox properties of the LOV1 domain from phototropin of the green alga Chlamydomonas reinhardtii. By equilibrium-redox spectropotentiometry a redox potential [E-fq/fhq (flavoquinone/flavohydroquinone)] of -290 mV vs. the normal hydrogen electrode (NHE) was determined for the wild-type domain (LOV1-wt). A similar value of -280 mV was found for the mutant LOV1-C57G, in which the photoreactive cysteine is replaced by glycine. The recovery kinetics (photoadduct--> ground state) in the photocycle of LOV1-wt are not influenced by a redox potential in the range between +500 and -260 mV versus NHE. No flavosemiquinone could be generated by chemical reduction with sodium dithionite. However photoreduction of LOV1-C57G with EDTA leads exclusively to the flavosemiquinone. This semiquinone is stable against disproportionation, and the photoreduction is not mediated by free FMN.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | BLUE-LIGHT RECEPTOR; ALGA CHLAMYDOMONAS-REINHARDTII; AVENA-SATIVA; ELECTRON-TRANSFER; PHOT-LOV1 DOMAIN; FLAVIN; PHOTOTROPIN; MECHANISM; PROTEIN; FLAVOPROTEINS; flavins; photochemistry; photocycles; photoreceptors; redox chemistry |
| Subjects: | 500 Science > 540 Chemistry & allied sciences 500 Science > 580 Botanical sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Pflanzenwissenschaften > Lehrstuhl für Zellbiologie und Pflanzenphysiologie (Prof. Dr. Klaus Grasser) Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Molecular Spectroscopy and Photochemistry) > Prof. Dr. Bernhard Dick |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 25 Nov 2020 06:40 |
| Last Modified: | 25 Nov 2020 06:40 |
| URI: | https://pred.uni-regensburg.de/id/eprint/31802 |
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