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Benditkis AS, Ashikhmin AA, Moskalenko AA, Krasnovsky AA. Photogeneration and quenching of singlet molecular oxygen by bacterial C 40 carotenoids with long chain of conjugated double bonds. PHOTOSYNTHESIS RESEARCH 2024; 159:291-301. [PMID: 38315423 DOI: 10.1007/s11120-023-01070-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 12/14/2023] [Indexed: 02/07/2024]
Abstract
Measurement of photosensitized luminescence of singlet oxygen has been applied to studies of singlet oxygen generation and quenching by C40 carotenoids (neurosporene, lycopene, rhodopin, and spirilloxanthin) with long chain of conjugated double bonds (CDB) using hexafluorobenzene as a solvent. It has been found that neurosporene, lycopene, and rhodopin are capable of the low efficient singlet oxygen generation in aerated solutions upon photoexcitation in the spectral region of their main absorption maxima. The quantum yield of this process was estimated to be (1.5-3.0) × 10-2. This value is near the singlet oxygen yields in solutions of ζ-carotene (7 CDB) and phytoene (3 CDB) and many-fold smaller than in solutions of phytofluene (5 CDB) (Ashikhmin et al. Biochemistry (Mosc) 85:773-780, https://doi.org/10.1134/S0006297920070056 , 2020, Biochemistry (Mosc) 87:1169-1178, 2022, https://doi.org/10.1134/S00062979221001082022 ). Photogeneration of singlet oxygen was not observed in spirilloxanthin solutions. A correlation was found between the singlet oxygen yields and the quantum yields and lifetimes of the fluorescence of the carotenoid molecules. All carotenoids were shown to be strong physical quenchers of singlet oxygen. The rate constants of 1O2 quenching by the carotenoids with long chain of CDB (9-13) were close to the rate constant of the diffusion-limited reactions ≈1010 M-1 s-1, being many-fold greater than the rate constants of 1O2 quenching by the carotenoids with the short chain of CDB (3-7) phytoene, phytofluene, and ζ-carotene studied in prior papers of our group (Ashikhmin et al. 2020, 2022). To our knowledge, the quenching rate constants of rhodopin and spirilloxanthin have been obtained in this paper for the first time. The mechanisms of 1O2 photogeneration by carotenoids in solution and in the LH2 complexes of photosynthetic cells, as well as the efficiencies of their protective action are discussed.
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Affiliation(s)
- A S Benditkis
- A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 119071, Moscow, Russia
| | - A A Ashikhmin
- Pushchino Scientific Center for Biological Research of Russian Academy of Sciences, Institute of Basic Biological Problems, Russian Academy of Sciences, 142290, Pushchino, Russia
| | - A A Moskalenko
- Pushchino Scientific Center for Biological Research of Russian Academy of Sciences, Institute of Basic Biological Problems, Russian Academy of Sciences, 142290, Pushchino, Russia
| | - A A Krasnovsky
- A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 119071, Moscow, Russia.
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Rozanowska M, Edge R, Land EJ, Navaratnam S, Sarna T, Truscott TG. Scavenging of Cation Radicals of the Visual Cycle Retinoids by Lutein, Zeaxanthin, Taurine, and Melanin. Int J Mol Sci 2023; 25:506. [PMID: 38203675 PMCID: PMC10779001 DOI: 10.3390/ijms25010506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/26/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
In the retina, retinoids involved in vision are under constant threat of oxidation, and their oxidation products exhibit deleterious properties. Using pulse radiolysis, this study determined that the bimolecular rate constants of scavenging cation radicals of retinoids by taurine are smaller than 2 × 107 M-1s-1 whereas lutein scavenges cation radicals of all three retinoids with the bimolecular rate constants approach the diffusion-controlled limits, while zeaxanthin is only 1.4-1.6-fold less effective. Despite that lutein exhibits greater scavenging rate constants of retinoid cation radicals than other antioxidants, the greater concentrations of ascorbate in the retina suggest that ascorbate may be the main protectant of all visual cycle retinoids from oxidative degradation, while α-tocopherol may play a substantial role in the protection of retinaldehyde but is relatively inefficient in the protection of retinol or retinyl palmitate. While the protection of retinoids by lutein and zeaxanthin appears inefficient in the retinal periphery, it can be quite substantial in the macula. Although the determined rate constants of scavenging the cation radicals of retinol and retinaldehyde by dopa-melanin are relatively small, the high concentration of melanin in the RPE melanosomes suggests they can be scavenged if they are in proximity to melanin-containing pigment granules.
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Affiliation(s)
- Malgorzata Rozanowska
- Cardiff Institute of Tissue Engineering and Repair, Cardiff University, Cardiff CF10 3AX, UK
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Ruth Edge
- Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row, Cumbria CA24 3HA, UK;
| | - Edward J. Land
- The Paterson Institute, The University of Manchester, Wilmslow Road, Manchester M20 4BX, UK;
| | - Suppiah Navaratnam
- Biomedical Sciences Research Institute, University of Salford, Manchester M5 4WT, UK;
| | - Tadeusz Sarna
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland;
| | - T. George Truscott
- School of Chemical and Physical Sciences, Lennard-Jones Building, Keele University, Staffordshire ST5 5BG, UK;
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Telegina TA, Vechtomova YL, Aybush AV, Buglak AA, Kritsky MS. Isomerization of carotenoids in photosynthesis and metabolic adaptation. Biophys Rev 2023; 15:887-906. [PMID: 37974987 PMCID: PMC10643480 DOI: 10.1007/s12551-023-01156-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 09/22/2023] [Indexed: 11/19/2023] Open
Abstract
In nature, carotenoids are present as trans- and cis-isomers. Various physical and chemical factors like light, heat, acids, catalytic agents, and photosensitizers can contribute to the isomerization of carotenoids. Living organisms in the process of evolution have developed different mechanisms of adaptation to light stress, which can also involve isomeric forms of carotenoids. Particularly, light stress conditions can enhance isomerization processes. The purpose of this work is to review the recent studies on cis/trans isomerization of carotenoids as well as the role of carotenoid isomers for the light capture, energy transfer, photoprotection in light-harvesting complexes, and reaction centers of the photosynthetic apparatus of plants and other photosynthetic organisms. The review also presents recent studies of carotenoid isomers for the biomedical aspects, showing cis- and trans-isomers differ in bioavailability, antioxidant activity and biological activity, which can be used for therapeutic and prophylactic purposes.
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Affiliation(s)
- T. A. Telegina
- Research Center of Biotechnology of the Russian Academy of Sciences, 33 Leninsky Prospect, Building 2, 119071 Moscow, Russia
| | - Yuliya L. Vechtomova
- Research Center of Biotechnology of the Russian Academy of Sciences, 33 Leninsky Prospect, Building 2, 119071 Moscow, Russia
| | - A. V. Aybush
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 4 Kosygina Street, Building 1, 119991 Moscow, Russia
| | - A. A. Buglak
- Saint Petersburg State University, 7-9 Universitetskaya Emb., 199034 Saint Petersburg, Russia
| | - M. S. Kritsky
- Research Center of Biotechnology of the Russian Academy of Sciences, 33 Leninsky Prospect, Building 2, 119071 Moscow, Russia
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Biswas S, Niedzwiedzki DM, Pakrasi HB. Energy dissipation efficiency in the CP43 assembly intermediate complex of photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148982. [PMID: 37146928 DOI: 10.1016/j.bbabio.2023.148982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/10/2023] [Accepted: 04/20/2023] [Indexed: 05/07/2023]
Abstract
Photosystem II in oxygenic organisms is a large membrane bound rapidly turning over pigment protein complex. During its biogenesis, multiple assembly intermediates are formed, including the CP43-preassembly complex (pCP43). To understand the energy transfer dynamics in pCP43, we first engineered a His-tagged version of the CP43 in a CP47-less strain of the cyanobacterium Synechocystis 6803. Isolated pCP43 from this engineered strain was subjected to advanced spectroscopic analysis to evaluate its excitation energy dissipation characteristics. These included measurements of steady-state absorption and fluorescence emission spectra for which correlation was tested with Stepanov relation. Comparison of fluorescence excitation and absorptance spectra determined that efficiency of energy transfer from β-carotene to chlorophyll a is 39 %. Time-resolved fluorescence images of pCP43-bound Chl a were recorded on streak camera, and fluorescence decay dynamics were evaluated with global fitting. These demonstrated that the decay kinetics strongly depends on temperature and buffer used to disperse the protein sample and fluorescence decay lifetime was estimated in 3.2-5.7 ns time range, depending on conditions. The pCP43 complex was also investigated with femtosecond and nanosecond time-resolved absorption spectroscopy upon excitation of Chl a and β-carotene to reveal pathways of singlet excitation relaxation/decay, Chl a triplet dynamics and Chl a → β-carotene triplet state sensitization process. The latter demonstrated that Chl a triplet in the pCP43 complex is not efficiently quenched by carotenoids. Finally, detailed kinetic analysis of the rise of the population of β-carotene triplets determined that the time constant of the carotenoid triplet sensitization is 40 ns.
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Affiliation(s)
- Sandeep Biswas
- Department of Biology, Washington University, St. Louis, MO 63130, USA.
| | - Dariusz M Niedzwiedzki
- Center for Solar Energy and Energy Storage, Washington University, St. Louis, MO 63130, USA; Department of Energy, Environmental & Chemical Engineering, Washington University, St. Louis, MO 63130, USA.
| | - Himadri B Pakrasi
- Department of Biology, Washington University, St. Louis, MO 63130, USA.
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Biswas S, Niedzwiedzki DM, Pakrasi HB. Introduction of cysteine-mediated quenching in the CP43 protein of photosystem II builds resilience to high-light stress in a cyanobacterium. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148580. [PMID: 35654167 DOI: 10.1016/j.bbabio.2022.148580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 05/16/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Photosystem (PS) II is prone to photodamage both as a direct consequence of light, and indirectly by producing reactive oxygen species. Engineering high-light tolerance in cyanobacteria with minimal impact on PSII function is desirable in synthetic biology. IsiA, a CP43 homolog found exclusively in cyanobacteria, can dissipate excess light energy. We have recently determined that the sole cysteine residue of IsiA in Synechocystis sp. PCC 6803 has a critical role in non-photochemical quenching. Similar cysteine-mediated energy quenching has also been observed in green‑sulfur bacteria. Sequence analysis of IsiA and CP43 aligns cysteine 260 of IsiA with valine 277 of CP43 in Synechocystis sp. PCC 6803. In the current study, we explore the impact of replacing valine 277 of CP43 to a cysteine on growth, PSII activity and high-light tolerance. Our results imply a decline in the PSII output for the mutant (CP43V277C) presumably due to the dissipation of absorbed light energy by cysteine. Spectroscopic analysis of isolated PSII from this mutant strain also suggests a delayed transfer of excitation energy from CP43-associated chlorophyll a to PSII reaction center. The mutation makes the PSII high-light tolerant and provides a small advantage in growth under high-light conditions. This previously unexplored strategy to engineer high-light tolerance could be a step further towards developing cyanobacterial cells as biofactories.
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Affiliation(s)
- Sandeep Biswas
- Department of Biology, Washington University, St. Louis, MO 63130, USA.
| | - Dariusz M Niedzwiedzki
- Center for Solar Energy and Energy Storage, Washington University, St. Louis, MO 63130, USA; Department of Energy, Environmental & Chemical Engineering, Washington University, St. Louis, MO 63130, USA.
| | - Himadri B Pakrasi
- Department of Biology, Washington University, St. Louis, MO 63130, USA.
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Zbyradowski M, Duda M, Wisniewska-Becker A, Heriyanto, Rajwa W, Fiedor J, Cvetkovic D, Pilch M, Fiedor L. Triplet-driven chemical reactivity of β-carotene and its biological implications. Nat Commun 2022; 13:2474. [PMID: 35513374 PMCID: PMC9072317 DOI: 10.1038/s41467-022-30095-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/14/2022] [Indexed: 11/09/2022] Open
Abstract
The endoperoxides of β-carotene (βCar-EPOs) are regarded as main products of the chemical deactivation of 1O2 by β-carotene, one of the most important antioxidants, following a concerted singlet-singlet reaction. Here we challenge this view by showing that βCar-EPOs are formed in the absence of 1O2 in a non-concerted triplet-triplet reaction: 3O2 + 3β-carotene → βCar-EPOs, in which 3β-carotene manifests a strong biradical character. Thus, the reactivity of β-carotene towards oxygen is governed by its excited triplet state. βCar-EPOs, while being stable in the dark, are photochemically labile, and are a rare example of nonaromatic endoperoxides that release 1O2, again not in a concerted reaction. Their light-induced breakdown triggers an avalanche of free radicals, which accounts for the pro-oxidant activity of β-carotene and the puzzling swap from its anti- to pro-oxidant features. Furthermore, we show that βCar-EPOs, and carotenoids in general, weakly sensitize 1O2. These findings underlie the key role of the triplet state in determining the chemical and photophysical features of β-carotene. They shake up the prevailing models of carotenoid photophysics, the anti-oxidant functioning of β-carotene, and the role of 1O2 in chemical signaling in biological photosynthetic systems. βCar-EPOs and their degradation products are not markers of 1O2 and oxidative stress but of the overproduction of extremely hazardous chlorophyll triplets in photosystems. Hence, the chemical signaling of overexcitation of the photosynthetic apparatus is based on a 3chlorophyll-3β-carotene relay, rather than on extremely short-lived 1O2.
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Affiliation(s)
- Mateusz Zbyradowski
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland
| | - Mariusz Duda
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland
| | - Anna Wisniewska-Becker
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland
| | - Heriyanto
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland.,Ma Chung Research Center for Photosynthetic Pigments, Ma Chung University, Villa Puncak Tidar N-01, Malang, 65151, Indonesia
| | - Weronika Rajwa
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland
| | - Joanna Fiedor
- Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Mickiewicza 30, 30-059, Cracow, Poland
| | - Dragan Cvetkovic
- Faculty of Technology, University of Niš, 16000, Leskovac, Serbia
| | - Mariusz Pilch
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland.,Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Kraków, Poland
| | - Leszek Fiedor
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland.
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Różanowska MB, Pawlak A, Różanowski B. Products of Docosahexaenoate Oxidation as Contributors to Photosensitising Properties of Retinal Lipofuscin. Int J Mol Sci 2021; 22:ijms22073525. [PMID: 33805370 PMCID: PMC8037991 DOI: 10.3390/ijms22073525] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/24/2021] [Accepted: 03/25/2021] [Indexed: 12/16/2022] Open
Abstract
Retinal lipofuscin which accumulates with age in the retinal pigment epithelium (RPE) is subjected to daily exposures to high fluxes of visible light and exhibits potent photosensitising properties; however, the molecules responsible for its photoreactivity remain unknown. Here, we demonstrate that autooxidation of docosahexaenoate (DHE) leads to the formation of products absorbing, in addition to UVB and UVA light, also visible light. The products of DHE oxidation exhibit potent photosensitising properties similar to photosensitising properties of lipofuscin, including generation of an excited triplet state with similar characteristics as the lipofuscin triplet state, and photosensitised formation of singlet oxygen and superoxide. The quantum yields of singlet oxygen and superoxide generation by oxidised DHE photoexcited with visible light are 2.4- and 3.6-fold higher, respectively, than for lipofuscin, which is consistent with the fact that lipofuscin contains some chromophores which do contribute to the absorption of light but not so much to its photosensitising properties. Importantly, the wavelength dependence of photooxidation induced by DHE oxidation products normalised to equal numbers of incident photons is also similar to that of lipofuscin—it steeply increases with decreasing wavelength. Altogether, our results demonstrate that products of DHE oxidation include potent photosensitiser(s) which are likely to contribute to lipofuscin photoreactivity.
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Affiliation(s)
- Małgorzata B. Różanowska
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4HQ, Wales, UK
- Cardiff Institute for Tissue Engineering and Repair (CITER), Cardiff University, Cardiff CF24 4HQ, Wales, UK
- Correspondence: ; Tel.: +44-292087-5057
| | - Anna Pawlak
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland;
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Kundu A, Dasgupta J. Photogeneration of Long-Lived Triplet States through Singlet Fission in Lycopene H-Aggregates. J Phys Chem Lett 2021; 12:1468-1474. [PMID: 33528257 DOI: 10.1021/acs.jpclett.0c03301] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Molecular triplet excitons produced through singlet fission (SF) usually have shorter triplet lifetimes due to exciton-exciton recombination and relaxation pathways, thereby resulting in complex device architectures for SF-boosted solar cells. Using broadband transient absorption spectroscopy, we here show that the photoexcitation of nanostructured lycopene H-aggregates at room temperature produces free triplets with an unprecedented 35-fold enhancement in the lifetime compared to those localized on the monomer backbone. The observed rise of a spectrally blue-shifted correlated T-T pair state in ∼19 ps with distinct vibronic features provides the basis for SF-induced triplet generation.
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Affiliation(s)
- Arup Kundu
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
| | - Jyotishman Dasgupta
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
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Zhou Y, Karl T, Lewis DH, McGhie TK, Arathoon S, Davies KM, Ryan KG, Gould KS, Schwinn KE. Production of Betacyanins in Transgenic Nicotiana tabacum Increases Tolerance to Salinity. FRONTIERS IN PLANT SCIENCE 2021; 12:653147. [PMID: 33995448 PMCID: PMC8121086 DOI: 10.3389/fpls.2021.653147] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 04/09/2021] [Indexed: 05/03/2023]
Abstract
Although red betalain pigments (betacyanins) have been associated with salinity tolerance in some halophytes like Disphyma australe, efforts to determine whether they have a causal role and the underlying mechanisms have been hampered by a lack of a model system. To address this, we engineered betalain-producing Nicotiana tabacum, by the introduction of three betalain biosynthetic genes. The plants were violet-red due to the accumulation of three betacyanins: betanin, isobetanin, and betanidin. Under salt stress, betacyanic seedlings had increased survivability and leaves of mature plants had higher photochemical quantum yields of photosystem II (F v /F m ) and faster photosynthetic recovery after saturating light treatment. Under salt stress, compared to controls betacyanic leaf disks had no loss of carotenoids, a slower rate of chlorophyll degradation, and higher F v /F m values. Furthermore, simulation of betacyanin pigmentation by using a red filter cover improved F v /F m value of green tissue under salt stress. Our results confirm a direct causal role of betacyanins in plant salinity tolerance and indicate a key mechanism is photoprotection. A role in delaying leaf senescence was also indicated, and the enhanced antioxidant capability of the betacyanic leaves suggested a potential contribution to scavenging reactive oxygen species. The study can inform the development of novel biotechnological approaches to improving agricultural productivity in saline-affected areas.
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Affiliation(s)
- Yanfei Zhou
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Tanja Karl
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - David H. Lewis
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Tony K. McGhie
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Steve Arathoon
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Kevin M. Davies
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Ken G. Ryan
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Kevin S. Gould
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Kathy E. Schwinn
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
- *Correspondence: Kathy E. Schwinn,
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Hui J, Dong PT, Liang L, Mandal T, Li J, Ulloa ER, Zhan Y, Jusuf S, Zong C, Seleem MN, Liu GY, Cui Q, Cheng JX. Photo-Disassembly of Membrane Microdomains Revives Conventional Antibiotics against MRSA. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1903117. [PMID: 32195102 PMCID: PMC7080515 DOI: 10.1002/advs.201903117] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 12/29/2019] [Indexed: 05/21/2023]
Abstract
Confronted with the rapid evolution and dissemination of antibiotic resistance, there is an urgent need to develop alternative treatment strategies for drug-resistant pathogens. Here, an unconventional approach is presented to restore the susceptibility of methicillin-resistant S. aureus (MRSA) to a broad spectrum of conventional antibiotics via photo-disassembly of functional membrane microdomains. The photo-disassembly of microdomains is based on effective photolysis of staphyloxanthin, the golden carotenoid pigment that gives its name. Upon pulsed laser treatment, cell membranes are found severely disorganized and malfunctioned to defense antibiotics, as unveiled by membrane permeabilization, membrane fluidification, and detachment of membrane protein, PBP2a. Consequently, the photolysis approach increases susceptibility and inhibits development of resistance to a broad spectrum of antibiotics including penicillins, quinolones, tetracyclines, aminoglycosides, lipopeptides, and oxazolidinones. The synergistic therapy, without phototoxicity to the host, is effective in combating MRSA both in vitro and in vivo in a mice skin infection model. Collectively, this endogenous chromophore-targeted phototherapy concept paves a novel platform to revive conventional antibiotics to combat drug-resistant S. aureus infections as well as to screen new lead compounds.
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Affiliation(s)
- Jie Hui
- Department of Electrical and Computer Engineering Boston University Boston MA 02215 USA
- Boston University Photonics Center Boston MA 02215 USA
| | - Pu-Ting Dong
- Boston University Photonics Center Boston MA 02215 USA
- Department of Chemistry Boston University Boston MA 02215 USA
| | - Lijia Liang
- Department of Electrical and Computer Engineering Boston University Boston MA 02215 USA
- State Key Laboratory of Supramolecular Structure and Materials Institute of Theoretical Chemistry Jilin University Changchun 130012 China
| | | | - Junjie Li
- Department of Electrical and Computer Engineering Boston University Boston MA 02215 USA
- Boston University Photonics Center Boston MA 02215 USA
| | - Erlinda R Ulloa
- Collaborative to Halt Antibiotic-Resistant Microbes (CHARM) Department of Pediatrics University of California San Diego School of Medicine La Jolla CA 92093 USA
- Division of Infectious Disease Department of Pediatrics Children's Hospital of Philadelphia Philadelphia PA 19104 USA
| | - Yuewei Zhan
- Department Biomedical Engineering Boston University Boston MA 02215 USA
| | - Sebastian Jusuf
- Department Biomedical Engineering Boston University Boston MA 02215 USA
| | - Cheng Zong
- Department of Electrical and Computer Engineering Boston University Boston MA 02215 USA
- Boston University Photonics Center Boston MA 02215 USA
| | - Mohamed N Seleem
- College of Veterinary Medicine Purdue University West Lafayette IN 47907 USA
| | - George Y Liu
- Collaborative to Halt Antibiotic-Resistant Microbes (CHARM) Department of Pediatrics University of California San Diego School of Medicine La Jolla CA 92093 USA
- Division of Infectious Diseases Rady Children's Hospital San Diego CA 92123 USA
| | - Qiang Cui
- Department of Chemistry Boston University Boston MA 02215 USA
- Department Biomedical Engineering Boston University Boston MA 02215 USA
| | - Ji-Xin Cheng
- Department of Electrical and Computer Engineering Boston University Boston MA 02215 USA
- Boston University Photonics Center Boston MA 02215 USA
- Department of Chemistry Boston University Boston MA 02215 USA
- Department Biomedical Engineering Boston University Boston MA 02215 USA
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11
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Dogra V, Kim C. Singlet Oxygen Metabolism: From Genesis to Signaling. FRONTIERS IN PLANT SCIENCE 2019; 10:1640. [PMID: 31969891 PMCID: PMC6960194 DOI: 10.3389/fpls.2019.01640] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 11/21/2019] [Indexed: 05/03/2023]
Abstract
Singlet oxygen (1O2) is an excited state of molecular oxygen with an electron spin shift in the molecular orbitals, which is extremely unstable and highly reactive. In plants, 1O2 is primarily generated as a byproduct of photosynthesis in the photosystem II reaction center (PSII RC) and the light-harvesting antenna complex (LHC) in the grana core (GC). This occurs upon the absorption of light energy when the excited chlorophyll molecules in the PSII transfer the excess energy to molecular oxygen, thereby generating 1O2. As a potent oxidant, 1O2 promotes oxidative damage. However, at sub-lethal levels, it initiates chloroplast-to-nucleus retrograde signaling to contribute to plant stress responses, including acclimation and cell death. The thylakoid membranes comprise two spatially separated 1O2 sensors: β-carotene localized in the PSII RC in the GC and the nuclear-encoded chloroplast protein EXECUTER1 (EX1) residing in the non-appressed grana margin (GM). Finding EX1 in the GM suggests the existence of an additional source of 1O2 in the GM and the presence of two distinct 1O2-signaling pathways. In this review, we mainly discuss the genesis and impact of 1O2 in plant physiology.
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Foyer CH. Reactive oxygen species, oxidative signaling and the regulation of photosynthesis. ENVIRONMENTAL AND EXPERIMENTAL BOTANY 2018; 154:134-142. [PMID: 30283160 PMCID: PMC6105748 DOI: 10.1016/j.envexpbot.2018.05.003] [Citation(s) in RCA: 338] [Impact Index Per Article: 56.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 05/03/2018] [Accepted: 05/03/2018] [Indexed: 05/18/2023]
Abstract
Reduction-oxidation (redox) reactions, in which electrons move from a donor to an acceptor, are the functional heart of photosynthesis. It is not surprising therefore that reactive oxygen species (ROS) are generated in abundance by photosynthesis, providing a plethora of redox signals as well as functioning as essential regulators of energy and metabolic fluxes. Chloroplasts are equipped with an elaborate and multifaceted protective network that allows photosynthesis to function with high productivity even in resource-limited natural environments. This includes numerous antioxidants with overlapping functions that provide enormous flexibility in redox control. ROS are an integral part of the repertoire of chloroplast signals that are transferred to the nucleus to convey essential information concerning redox pressure within the electron transport chain. Current evidence suggests that there is specificity in the gene-expression profiles triggered by the different ROS signals, so that singlet oxygen triggers programs related to over excitation of photosystem (PS) II while superoxide and hydrogen peroxide promote the expression of other suites of genes that may serve to alleviate electron pressure on the reducing side of PSI. Not all chloroplasts are equal in their signaling functions, with some sub-populations appearing to have better contacts/access to the nucleus than others to promote genetic and epigenetic responses. While the concept that light-induced increases in ROS result in damage to PSII and photoinhibition is embedded in the photosynthesis literature, there is little consensus concerning the extent to which such oxidative damage happens in nature. Slowly reversible decreases in photosynthetic capacity are not necessarily the result of light-induced damage to PSII reaction centers.
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13
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Dogra V, Rochaix JD, Kim C. Singlet oxygen-triggered chloroplast-to-nucleus retrograde signalling pathways: An emerging perspective. PLANT, CELL & ENVIRONMENT 2018; 41:1727-1738. [PMID: 29749057 DOI: 10.1111/pce.13332] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/27/2018] [Accepted: 04/27/2018] [Indexed: 05/19/2023]
Abstract
Singlet oxygen (1 O2 ) is a prime cause of photo-damage of the photosynthetic apparatus. The chlorophyll molecules in the photosystem II reaction center and in the light-harvesting antenna complex are major sources of 1 O2 generation. It has been thought that the generation of 1 O2 mainly takes place in the appressed regions of the thylakoid membranes, namely, the grana core, where most of the active photosystem II complexes are localized. Apart from being a toxic molecule, new evidence suggests that 1 O2 significantly contributes to chloroplast-to-nucleus retrograde signalling that primes acclimation and cell death responses. Interestingly, recent studies reveal that chloroplasts operate two distinct 1 O2 -triggered retrograde signalling pathways in which β-carotene and a nuclear-encoded chloroplast protein EXECUTER1 play essential roles as signalling mediators. The coexistence of these mediators raises several questions: their crosstalk, source(s) of 1 O2 , downstream signalling components, and the perception and reaction mechanism of these mediators towards 1 O2 . In this review, we mainly discuss the molecular genetic basis of the mode of action of these two putative 1 O2 sensors and their corresponding retrograde signalling pathways. In addition, we also propose the possible existence of an alternative source of 1 O2 , which is spatially and functionally separated from the grana core.
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Affiliation(s)
- Vivek Dogra
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Jean-David Rochaix
- Department of Molecular Biology and Plant Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Chanhong Kim
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
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Niedzwiedzki DM, Cranston L. Excited state lifetimes and energies of okenone and chlorobactene, exemplary keto and non-keto aryl carotenoids. Phys Chem Chem Phys 2015; 17:13245-56. [DOI: 10.1039/c5cp00836k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Photophysical properties of two typical aryl carotenoids, okenone and chlorobactene, were studied with application of femtosecond and microsecond time-resolved absorption spectroscopies.
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Affiliation(s)
- Dariusz M. Niedzwiedzki
- Photosynthetic Antenna Research Center and Department of Chemistry
- Washington University in St Louis
- USA
| | - Laura Cranston
- Institute of Molecular Cell and Systems Biology
- College of Medical
- Veterinary and Life Sciences
- University of Glasgow
- Glasgow Biomedical Research Centre
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Li H, Zhang P, Song X, Wang W. Determination of Astaxanthin and Canthaxanthin Triplet Properties in Different Polarities of the Solvent by Laser Flash Photolysis. CHINESE J CHEM 2011. [DOI: 10.1002/cjoc.201180276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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16
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Niedzwiedzki DM, Fuciman M, Frank HA, Blankenship RE. Energy transfer in an LH4-like light harvesting complex from the aerobic purple photosynthetic bacterium Roseobacter denitrificans. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:518-28. [DOI: 10.1016/j.bbabio.2011.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 03/08/2011] [Accepted: 03/11/2011] [Indexed: 11/25/2022]
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17
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Fuciman M, Enriquez MM, Kaligotla S, Niedzwiedzki DM, Kajikawa T, Aoki K, Katsumura S, Frank HA. Singlet and Triplet State Spectra and Dynamics of Structurally Modified Peridinins. J Phys Chem B 2011; 115:4436-45. [DOI: 10.1021/jp110092c] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marcel Fuciman
- Department of Chemistry, University of Connecticut, U-3060, 55 North Eagleville Road, Storrs, Connecticut 06269-3060, United States
| | - Miriam M. Enriquez
- Department of Chemistry, University of Connecticut, U-3060, 55 North Eagleville Road, Storrs, Connecticut 06269-3060, United States
| | - Shanti Kaligotla
- Department of Chemistry, University of Connecticut, U-3060, 55 North Eagleville Road, Storrs, Connecticut 06269-3060, United States
| | - Dariusz M. Niedzwiedzki
- Department of Chemistry, University of Connecticut, U-3060, 55 North Eagleville Road, Storrs, Connecticut 06269-3060, United States
| | - Takayuki Kajikawa
- Department of Chemistry, Kwansei Gakuin University, 669-1337, Hyogo, Japan
| | - Kazuyoshi Aoki
- Department of Chemistry, Kwansei Gakuin University, 669-1337, Hyogo, Japan
| | - Shigeo Katsumura
- Department of Chemistry, Kwansei Gakuin University, 669-1337, Hyogo, Japan
| | - Harry A. Frank
- Department of Chemistry, University of Connecticut, U-3060, 55 North Eagleville Road, Storrs, Connecticut 06269-3060, United States
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18
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Niedzwiedzki DM, Kobayashi M, Blankenship RE. Triplet excited state spectra and dynamics of carotenoids from the thermophilic purple photosynthetic bacterium Thermochromatium tepidum. PHOTOSYNTHESIS RESEARCH 2011; 107:177-186. [PMID: 21229315 DOI: 10.1007/s11120-011-9620-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 12/31/2010] [Indexed: 05/30/2023]
Abstract
Light-harvesting complex 2 from the anoxygenic phototrophic purple bacterium Thermochromatium tepidum was purified and studied by steady-state absorption, fluorescence and flash photolysis spectroscopy. Steady-state absorption and fluorescence measurements show that carotenoids play a negligible role as supportive energy donors and transfer excitation to bacteriochlorophyll-a with low energy transfer efficiency of ~30%. HPLC analysis determined that the dominant carotenoids in the complex are rhodopin and spirilloxanthin. Carotenoid excited triplet state formation upon direct (carotenoid) or indirect (bacteriochlorophyll-a Q(x) band) excitation shows that carotenoid triplets are mostly localized on spirilloxanthin. In addition, no triplet excitation transfer between carotenoids was observed. Such specific carotenoid composition and spectroscopic results strongly suggest that this organism optimized carotenoid composition in the light-harvesting complex 2 in order to maximize photoprotective capabilities of carotenoids but subsequently drastically suppressed their supporting role in light-harvesting process.
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Kaligotla S, Doyle S, Niedzwiedzki DM, Hasegawa S, Kajikawa T, Katsumura S, Frank HA. Triplet state spectra and dynamics of peridinin analogs having different extents of pi-electron conjugation. PHOTOSYNTHESIS RESEARCH 2010; 103:167-174. [PMID: 20165916 DOI: 10.1007/s11120-010-9535-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 02/04/2010] [Indexed: 05/28/2023]
Abstract
The Peridinin-Chlorophyll a-Protein (PCP) complex has both an exceptionally efficient light-harvesting ability and a highly effective protective capacity against photodynamic reactions involving singlet oxygen. These functions can be attributed to presence of a substantial amount of the highly-substituted and complex carotenoid, peridinin, in the protein and the facts that the low-lying singlet states of peridinin are higher in energy than those of chlorophyll (Chl) a, but the lowest-lying triplet state of peridinin is below that of Chl a. Thus, singlet energy can be transferred from peridinin to Chl a, but the Chl a triplet state is quenched before it can sensitize the formation of singlet oxygen. The present investigation takes advantage of Chl a as an effective triplet state donor to peridinin and explores the triplet state spectra and dynamics of a systematic series of peridinin analogs having different numbers of conjugated carbon-carbon double bonds. The carotenoids investigated are peridinin, which has a C(37) carbon skeleton and eight conjugated carbon-carbon double bonds, and three synthetic analogs: C(33)-peridinin, having two less double bonds than peridinin, C(35)-peridinin which has one less double bond than peridinin, and C(39)-peridinin which has one more double bond than peridinin. In this study, the behavior of the triplet state spectra and kinetics exhibited by these molecules has been investigated in polar and nonpolar solvents and reveals a substantial effect of both pi-electron conjugated chain length and solvent environment on the spectral lineshapes. However, only a small dependence of these factors is observed on the kinetics of triplet energy transfer from Chl a and on carotenoid triplet state deactivation to the ground state.
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Affiliation(s)
- Shanti Kaligotla
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA
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20
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Guo WH, Tu CY, Hu CH. Cis-trans isomerizations of beta-carotene and lycopene: a theoretical study. J Phys Chem B 2008; 112:12158-67. [PMID: 18754638 DOI: 10.1021/jp8019705] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The all-trans to mono-cis isomerizations of polyenes and two C40H56 carotenes, beta-carotene and lycopene, at the ground singlet (S0) and triplet (T1) states are studied by means of quantum chemistry computations. At the S0 state of polyenes containing n acetylene units (Pn), we find that the energy barrier of the central C=C rotation decreases with n. In contrast, however, at the T 1 state, the rotational barrier increases with n. For the C40H56 carotenes, the rotational barriers of lycopene are lower than those of their beta-carotene counterparts. This difference renders the rotational rates of lycopene to be 1-2 orders of magnitude higher than those of beta-carotene at room temperature. For both these carotenes, the barrier is lowest for the rotation toward the 13-cis isomer. The relative abundances are in the following order: all-trans > 9-cis > 13-cis > 15-cis. Although the 5-cis isomer of lycopene has the lowest energy among the cis isomers, its formation from the all-trans form is restricted, owing to a very large rotational barrier. The possible physiological implications of this study are discussed.
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Affiliation(s)
- Wen-Hsin Guo
- Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan
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21
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Jańczyk A, Wolnicka-Głubisz A, Urbanska K, Stochel G, Macyk W. Photocytotoxicity of platinum(IV)-chloride surface modified TiO2 irradiated with visible light against murine macrophages. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2008; 92:54-58. [DOI: 10.1016/j.jphotobiol.2008.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 05/07/2008] [Accepted: 05/07/2008] [Indexed: 11/15/2022]
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22
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Han RM, Wul YS, Feng J, Ai XC, Zhang JP, Skibsted LH. Radical Cation Generation from Singlet and Triplet Excited States of All-trans-Lycopene in Chloroform¶. Photochem Photobiol 2007. [DOI: 10.1111/j.1751-1097.2004.tb00091.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Fiedor J, Fiedor L, Haessner R, Scheer H. Cyclic endoperoxides of β-carotene, potential pro-oxidants, as products of chemical quenching of singlet oxygen. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1709:1-4. [PMID: 15993379 DOI: 10.1016/j.bbabio.2005.05.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 05/16/2005] [Accepted: 05/18/2005] [Indexed: 11/27/2022]
Abstract
Photoprotection by carotenoids is generally considered to be based on the photophysical quenching of triplets and singlet oxygen. There is also accumulating evidence of an alternative, chemical quenching of triplets and singlet oxygen by carotenoids. We report the identification of relatively stable cyclic mono- and diendoperoxides as first products of such an alternative reaction. Nevertheless, these species remain reactive and in the dark cause autooxidation of beta-carotene in our model system. Their formation could explain the intriguing pro-oxidant and cytotoxic activity of carotenoids.
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Affiliation(s)
- Joanna Fiedor
- Department of Plant Physiology and Biochemistry, Faculty of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Cracow, Poland.
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24
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Billsten HH, Pan J, Sinha S, Pascher T, Sundström V, Polívka T. Excited-State Processes in the Carotenoid Zeaxanthin after Excess Energy Excitation. J Phys Chem A 2005; 109:6852-9. [PMID: 16834041 DOI: 10.1021/jp052227s] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aiming for better understanding of the large complexity of excited-state processes in carotenoids, we have studied the excitation wavelength dependence of the relaxation dynamics in the carotenoid zeaxanthin. Excitation into the lowest vibrational band of the S2 state at 485 nm, into the 0-3 vibrational band of the S2 state at 400 nm, and into the 2B(u)+ state at 266 nm resulted in different relaxation patterns. While excitation at 485 nm produces the known four-state scheme (S2 --> hot S1 --> S1 --> S0), excess energy excitation led to additional dynamics occurring with a time constant of 2.8 ps (400 nm excitation) and 4.9 ps (266 nm excitation), respectively. This process is ascribed to a conformational relaxation of conformers generated by the excess energy excitation. The zeaxanthin S state was observed regardless of the excitation wavelength, but its population increased after 400 and 266 nm excitation, suggesting that conformers generated by the excess energy excitation are important for directing the population toward the S state. The S2-S1 internal conversion time was shortened from 135 to 70 fs when going from 485 to 400 nm excitation, as a result of competition between the S2-S1 internal conversion from the vibrationally hot S2 state and S2 vibrational relaxation. The S1 lifetime of zeaxanthin was within experimental error the same for all excitation wavelengths, yielding approximately 9 ps. No long-lived species have been observed after excitation by femtosecond pulses regardless of the excitation wavelength, but excitation by nanosecond pulses at 266 nm generated both zeaxanthin triplet state and cation radical.
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Affiliation(s)
- Helena Hörvin Billsten
- Department of Chemical Physics, Chemical Center, Lund University, Box 124, 22100 Lund, Sweden
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25
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Freyer W, Mueller S, Teuchner K. Photophysical properties of benzoannelated metal-free phthalocyanines. J Photochem Photobiol A Chem 2004. [DOI: 10.1016/j.jphotochem.2003.12.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Montenegro MA, Rios ADO, Mercadante AZ, Nazareno MA, Borsarelli CD. Model studies on the photosensitized isomerization of bixin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2004; 52:367-373. [PMID: 14733523 DOI: 10.1021/jf0349026] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The photosensitized isomerization reaction of the natural cis carotenoid bixin (methyl hydrogen 9'-cis-6, 6'-diapocarotene-6, 6'-dioate) with rose bengal or methylene blue as the sensitizer in acetonitrile/methanol (1:1) solution was studied using UV-vis spectroscopy, high-performance liquid chromatography (HPLC), and time-resolved spectroscopic techniques, such as laser-flash photolysis and singlet oxygen phosphorescence detection. In both N(2)- and air-saturated solutions, the main product formed was all-trans-bixin. The observed isomerization rate constants, k(obs), decreased in the presence of air or with increase in the bixin concentration, suggesting the participation of the excited triplet state of bixin, (3)Bix, as precursor of the cis--> trans process. On the other hand, bixin solutions in the absence of sensitizer and/or light did not degrade, indicating that the ground state of bixin is stable to thermal isomerization at room temperature. Time-resolved spectroscopic experiments confirmed the formation of the excited triplet state of bixin and its deactivation by ground state bixin and molecular oxygen quenching processes. The primary isomerization products only degraded in the presence of air and under prolonged illumination conditions, probably due to the formation of oxidation products by reaction with singlet molecular oxygen. An energy-transfer mechanism was used to explain the observed results for the bixin transformations, and the consequences for food color are discussed.
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Affiliation(s)
- Mariana A Montenegro
- Instituto de Ciencias Químicas, Universidad Nacional de Santiago del Estero, Av. Belgrano (S) 1912, 4200 Santiago del Estero, Argentina
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Losi A, Yruela I, Reus M, Holzwarth AR, Braslavsky SE. Structural changes upon excitation of D1-D2-Cyt b559 photosystem II reaction centers depend on the beta-carotene content. Photochem Photobiol Sci 2003; 2:722-9. [PMID: 12911219 DOI: 10.1039/b301282d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Different preparations of D1-D2-Cyt b559 complexes from spinach with different beta-carotene (Car) content [on average from <0.5 to 2 per reaction center (RC)] were studied by means of laser-induced optoacoustic spectroscopy. phiP680(+)Pheo(-) does not depend on the preparation (or on the Car content) inasmuch as the magnitude of the prompt heat (produced within 20 ns) does not vary for the different samples upon excitation at 675 and 620 nm. The energy level of the primary charge-separated state, P680(+)Pheo(-), was determined as EP680(+)Pheo(-) = 1.55 eV. Thus, an enthalpy change accompanying charge separation from excited P680 of deltaH*P680Pheo-->P680(+)Pheo(-) = -0.27 eV is obtained. Calculations using the heat evolved during the time-resolved decay of P680(+)Pheo(-) (< or = 100 ns) affords a triplet (3[P680Pheo]) quantum yield phi3[P680Pheo] = 0.5 +/- 0.14. The structural volume change, deltaV1, corresponding to the formation of P680(+)Pheo(-), strongly depends on the Car content; it is ca. -2.5 A3 molecule(-1) for samples with <0.5 Car on average, decreases (in absolute value) to -0.5 +/- 0.2 A3 for samples with an average of 1 Car, and remains the same for samples with two Cars per RC. This suggests that the Car molecules induce changes in the ground-state RC conformation, an idea which was confirmed by preferential excitation of Car with blue light, which produced different carotene triplet lifetimes in samples with 2 Car compared to those containing less carotene. We conclude that the two beta-carotenes are not structurally equivalent. Upon blue-light excitation (480 nm, preferential carotene absorption) the fraction of energy stored is ca. 60% for the 9Chl-2Car sample, whereas it is 40% for the preparations with one or less Cars on average, indicating different paths of energy distribution after Car excitation in these RCs with remaining chlorophyll antennae.
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Affiliation(s)
- Aba Losi
- Max-Planck-Institut für Strahlenchemie, Postfach 10 13 65, 45413 Mülheim an der Ruhr, Germany
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