Excited-state dynamics of astaxanthin aggregates

Fuciman, Marcel; Durchan, Milan; Šlouf, Václav; Keşan, Gürkan; Polı́vka, Tomáš

doi:10.1016/j.cplett.2013.03.009

Cited by 28 publications

(41 citation statements)

References 37 publications

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“…The results (Fig. ) indicate that the peak arises from the carotenoid spheroidenone, which in the hexane‐solvated state has absorption maxima at 483 and 514 nm; the blue‐shifted 380 nm absorption could arise from a paired, parallel alignment of a pair of spheroidenone molecules (Fuciman et al ., ).…”

Section: Resultsmentioning

confidence: 97%

“…However, when pigments were examined by absorption spectroscopy and mass spectrometry it was found that this absorbance peak arises from the carotenoid spheroidenone. The absorbance maximum of the spheroidenone molecules in the FLAG‐PufQ eluate is blue‐shifted; this shift of carotenoid absorption to shorter wavelengths is a known phenomenon which occurs in aggregates known as H‐aggregates, in which the carotenoids align in a parallel orientation (Fuciman et al ., ). The purpose of the carotenoids within the FLAG‐PufQ eluate is unclear although a role in photoprotection of the PufQ protein complex is one possible explanation, which should be investigated in further studies.…”

Section: Discussionmentioning

confidence: 97%

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PufQ regulates porphyrin flux at the haem/bacteriochlorophyll branchpoint of tetrapyrrole biosynthesis via interactions with ferrochelatase

Chidgey

Jackson

Dickman

et al. 2017

Molecular Microbiology

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SummaryFacultative phototrophs such as Rhodobacter sphaeroides can switch between heterotrophic and photosynthetic growth. This transition is governed by oxygen tension and involves the large‐scale production of bacteriochlorophyll, which shares a biosynthetic pathway with haem up to protoporphyrin IX. Here, the pathways diverge with the insertion of Fe2+ or Mg2+ into protoporphyrin by ferrochelatase or magnesium chelatase, respectively. Tight regulation of this branchpoint is essential, but the mechanisms for switching between respiratory and photosynthetic growth are poorly understood. We show that PufQ governs the haem/bacteriochlorophyll switch; pufQ is found within the oxygen‐regulated pufQBALMX operon encoding the reaction centre–light‐harvesting photosystem complex. A pufQ deletion strain synthesises low levels of bacteriochlorophyll and accumulates the biosynthetic precursor coproporphyrinogen III; a suppressor mutant of this strain harbours a mutation in the hemH gene encoding ferrochelatase, substantially reducing ferrochelatase activity and increasing cellular bacteriochlorophyll levels. FLAG‐immunoprecipitation experiments retrieve a ferrochelatase‐PufQ‐carotenoid complex, proposed to regulate the haem/bacteriochlorophyll branchpoint by directing porphyrin flux toward bacteriochlorophyll production under oxygen‐limiting conditions. The co‐location of pufQ and the photosystem genes in the same operon ensures that switching of tetrapyrrole metabolism toward bacteriochlorophyll is coordinated with the production of reaction centre and light‐harvesting polypeptides.

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Section: Resultsmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 97%

PufQ regulates porphyrin flux at the haem/bacteriochlorophyll branchpoint of tetrapyrrole biosynthesis via interactions with ferrochelatase

Chidgey

Jackson

Dickman

et al. 2017

Molecular Microbiology

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“…Carotenoids, which have a significant role in biological systems, have been intensively investigated because of their rich photochemistry [1,2], photophysics [3,4], and photobiology properties [5]. Accordingly, numerous theoretical [6][7][8][9][10][11][12] and experimental [3,[12][13][14][15][16][17][18][19][20] studies have investigated the excited electronic structures, molecular configurations, and environmental effects for different carotenoids. Astaxanthin (AXT), which exists in the all-trans configuration, is a member of the carotenoid family containing C=O, O−H, and terminal β-ionone ring groups [13].…”

Section: Introductionmentioning

confidence: 99%

Raman and Infrared Spectra for All-trans-astaxanthin in Dimethyl Sulfoxide Solvent

Jiang

Liu

Yang

2017

Chinese Journal of Chemical Physics

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The Raman and infrared spectra of all-trans-astaxanthin (AXT) in dimethyl sulfoxide (DMSO) solvent were investigated experimentally and theoretically. Density functional calculations of the Raman spectra predict the splitting of the ν 1 band into ν 1-1 and ν 1-2 components. The absence of splitting in Raman experimental spectra is ascribed to the competition between the two symmetric C=C stretching vibrations of the backbone chain. The ν 1 band is very sensitive to the excitation wavelength: resonance excitation stimulates the higherfrequency ν 1-2 mode, and off-resonance excitation corresponds to the lower-frequency ν 1-1 mode. Analyses of the intramolecular hydrogen bonding between C=O and O−H in the AXT/DMSO system reveal that the C4=O1• • • H1−O3 and C4 ′ =O2• • • H2−O4 bonds are strengthened and weakened, respectively, in the electronically excited state compared with those in the ground state. This result reveals significant variations of the AXT molecular structure in different electronic states.

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“…In particular, their photophysical properties change dramatically with the environment due to the formation of different types of aggregates. 7,8 As many other carotenoids and chlorophylls, [9][10][11] AXT also forms aggregates when dissolved in hydrated polar solvents. 8,12 The water concentration in these mixtures influences the morphology of the aggregates, and, consequently, their properties.…”

Section: 4mentioning

confidence: 99%

“…In particular, spectroscopic analysis have shown that their absorption spectra can be blue shifted as well as red shifted compared to that of the isolated monomers depending on the aggregation conditions. 7,8,[12][13][14] The blue shift is attributed to the formation of H-aggregates and the red shift is attributed to the formation of J-aggregates. The H-aggregates formed by these molecules when deposited on surfaces or arranged at interfaces, hold promise as photoactive species in dye-sensitized solar cells.…”

Section: 4mentioning

confidence: 99%

Molecular Properties of Astaxanthin in Water/Ethanol Solutions from Computer Simulations

2016

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Astaxanthin (AXT) is a reference model of xanthophyll carotenoids, which is used in medicine and food industry, and has potential applications in nanotechnology. Because of its importance, there is a great interest in understanding its molecular properties and aggregation mechanism in water and mixed solvents. In this paper, we report a novel model of AXT for molecular dynamics simulation. The model is used to estimate different properties of the molecule in pure solutions and in water/ethanol mixtures. 1The calculated diffusion coefficients of AXT in pure water and ethanol are (3.22 ± 0.01) × 10 −6 cm 2 s −1 and (2.7 ± 0.4) × 10 −6 cm 2 s −1 , respectively.Our simulations also show that the content of water plays a clear effect on the morphology of the AXT aggregation in water/ethanol mixture. In up to 75% (v/v) water concentration, loosely connected network of dimers and trimers, and two-dimensional array structures are observed. At higher water concentrations, AXT molecules form more compact three-dimensional structures that are preferentially solvated by the ethanol molecules. The ethanol preferential binding and the formation of a well connected hydrogen bonding network on these AXT clusters, suggest that such preferential solvation can play an important role in controlling the aggregate structure.

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Excited-state dynamics of astaxanthin aggregates

Cited by 28 publications

References 37 publications

PufQ regulates porphyrin flux at the haem/bacteriochlorophyll branchpoint of tetrapyrrole biosynthesis via interactions with ferrochelatase

PufQ regulates porphyrin flux at the haem/bacteriochlorophyll branchpoint of tetrapyrrole biosynthesis via interactions with ferrochelatase

Raman and Infrared Spectra for All-trans-astaxanthin in Dimethyl Sulfoxide Solvent

Molecular Properties of Astaxanthin in Water/Ethanol Solutions from Computer Simulations

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