Linked Life Data

18989482

Source:http://linkedlifedata.com/resource/pubmed/id/18989482

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
44
pubmed:dateCreated
2008-11-7
pubmed:abstractText
In LOV2, the blue-light sensitive domain of phototropin, the primary photophysical event involves intersystem crossing (ISC) from the singlet-excited state to the triplet state. The ISC rate is enhanced in LOV2 as compared to flavin mononucleotide (FMN) in solution, which likely results from a heavy-atom effect of a nearby conserved cysteine, C450. Here, we applied fluorescence line narrowing (FLN), resonance Raman (RR) and Fourier-transform infrared (FTIR) spectroscopy to investigate the electronic structure of FMN bound to Avena sativa LOV2 (AsLOV2), its C450A mutant and Adiantum LOV2 (Phy3LOV2). We demonstrate that FLN is the method of choice to obtain accurate vibrational spectra on highly fluorescent flavoproteins. The vibrational spectrum of AsLOV2-C450A showed small but significant shifts with respect to those of wild type AsLOV2 and Phy3LOV2, with a systematic down-shift of Ring I vibrations, upshifts of Ring II and III vibrations and an upshift of the C2=O mode. These trends are similar to those in FMN model systems with an electron-donating group substituted at Ring I, known to induce a quinoid character to the electronic structure of oxidized flavin. Thus, enhancement of the ISC rate in LOV2 is induced through weak electron donation by the cysteine which mixes the FMN pi-electrons with the heavy sulfur orbitals, manifesting itself in a quinoid character of the ground electronic state of oxidized FMN. The proximity of the cysteine to FMN thus not only enables formation of a covalent adduct between FMN and cysteine, but also facilitates the rapid electronic formation of the reactive FMN triplet state.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
1463-9076
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
10
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6693-702
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Perturbation of the ground-state electronic structure of FMN by the conserved cysteine in phototropin LOV2 domains.
pubmed:affiliation
Department of Biophysics, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081HV, Amsterdam, The Netherlands. miaalex@nat.vu.nl
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't