title: Different Response of Carbonyl Carotenoids to Solvent Proticity Helps To Estimate Structure of the Unknown Carotenoid from Chromera velia.
abstract: In order to estimate the possible structure of the unknown carbonyl carotenoid related to isofucoxanthin from Chromera velia denoted as isofucoxanthin-like carotenoid (Ifx-l), we employed steady-state and ultrafast time-resolved spectroscopic techniques to investigate spectroscopic properties of Ifx-l in various solvents. The results were compared with those measured for related carotenoids with known structure: fucoxanthin (Fx) and isofucoxanthin (Ifx). The experimental data were complemented by quantum chemistry calculations and molecular modeling. The data show that Ifx-l must have longer effective conjugation length than Ifx. Yet, the magnitude of polarity-dependent changes in Ifx-l is larger than for Ifx, suggesting significant differences in structure of these two carotenoids. The most interesting spectroscopic feature of Ifx-l is its response to solvent proticity. The transient absorption data show that (1) the magnitude of the ICT-like band of Ifx-l in acetonitrile is larger than in methanol and (2) the S1/ICT lifetime of Ifx-l in acetonitrile, 4 ps, is markedly shorter than in methanol (10 ps). This is opposite behavior than for Fx and Ifx whose S1/ICT lifetimes are always shorter in protic solvent methanol (20 and 13 ps) than in aprotic acetonitrile (30 and 17 ps). Comparison with other carbonyl carotenoids reported earlier showed that proticity response of Ifx-l is consistent with presence of a conjugated lactone ring. Combining the experimental data and quantum chemistry calculations, we estimated a possible structure of Ifx-l.
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia , Branišovská 1760, 37005 České Budějovice, Czech Republic.
authors.forename: Gürkan
authors.initials: G
authors.lastname: Keşan
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia , Branišovská 1760, 37005 České Budějovice, Czech Republic.|Institute of Plant Molecular Biology, Biological Centre, Czech Academy of Sciences , České Budějovice, Czech Republic.
authors.forename: Milan
authors.initials: M
authors.lastname: Durchan
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia , Branišovská 1760, 37005 České Budějovice, Czech Republic.|Institute of Plant Molecular Biology, Biological Centre, Czech Academy of Sciences , České Budějovice, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Tichý
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia , Branišovská 1760, 37005 České Budějovice, Czech Republic.|Center for Nanobiology and Structural Biology, Institute of Microbiology and Global Change Research Center, Academy of Sciences of the Czech Republic , Nové Hrady, Czech Republic.
authors.forename: Babak
authors.initials: B
authors.lastname: Minofar
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia , Branišovská 1760, 37005 České Budějovice, Czech Republic.
authors.forename: Valentyna
authors.initials: V
authors.lastname: Kuznetsova
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia , Branišovská 1760, 37005 České Budějovice, Czech Republic.
authors.forename: Marcel
authors.initials: M
authors.lastname: Fuciman
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia , Branišovská 1760, 37005 České Budějovice, Czech Republic.
authors.forename: Václav
authors.initials: V
authors.lastname: Šlouf
authors.affiliation: Department of Physics, Dumlupınar University , Kütahya, Turkey.
authors.forename: Cemal
authors.initials: C
authors.lastname: Parlak
authors.affiliation: Institute of Physics and Biophysics, Faculty of Science, University of South Bohemia , Branišovská 1760, 37005 České Budějovice, Czech Republic.|Institute of Plant Molecular Biology, Biological Centre, Czech Academy of Sciences , České Budějovice, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Polívka
mesh_terms: D056893:Alveolata / Q000737:chemistry*; D002338:Carotenoids / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*
chemical_list: D012997:Solvents; D002338:Carotenoids