scholarly journals How carotenoids protect bacterial photosynthesis

2000 ◽  
Vol 355 (1402) ◽  
pp. 1345-1349 ◽  
Author(s):  
Richard J. Cogdell ◽  
Tina D. Howard ◽  
Robert Bittl ◽  
Erberhard Schlodder ◽  
Irene Geisenheimer ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Photosynthetic Bacteria ◽  
Bacterial Photosynthesis ◽  
Specific Reference ◽  
Structural Studies ◽  
Triplet Energy ◽  
Purple Photosynthetic Bacteria ◽  
Reaction Centres ◽  
Essential Function ◽  
Triplet Energy Transfer

The essential function of carotenoids in photosynthesis is to act as photoprotective agents, preventing chlorophylls and bacteriochlorophylls from sensitizing harmful photodestructive reactions in the presence of oxygen. Based upon recent structural studies on reaction centres and antenna complexes from purple photosynthetic bacteria, the detailed organization of the carotenoids is described. Then with specific reference to bacterial antenna complexes the details of the photoprotective role, triplet–triplet energy transfer, are presented.

Carotenoids in photosynthesis

1978 ◽  
Vol 284 (1002) ◽  
pp. 569-579 ◽  
Keyword(s):  
Energy Transfer ◽  
Photosynthetic Bacteria ◽  
Light Harvesting ◽  
Protective Role ◽  
Reaction Centre ◽  
Triplet Energy ◽  
Photosynthetic Unit ◽  
Accessory Pigment ◽  
Light Harvesting Antenna ◽  
Triplet Energy Transfer

Carotenoids are usually considered to perform two major functions in photosynthesis. They serve as accessory light harvesting pigments, extending the range of wavelengths over which light can drive photosynthesis, and they act to protect the chlorophyllous pigments from the harmful photodestructive reaction which occurs in the presence of oxygen. Drawing upon recent work with photosynthetic bacteria, evidence is presented as to how the carotenoids are organized within both portions of the photosynthetic unit (the light harvesting antenna and the reaction centre) and how they discharge both their functions. The accessory pigment role is a singlet-singlet energy transfer from the carotenoid to the bacteriochlorophyll, while the protective role is a triplet-triplet energy transfer from the bacteriochlorophyll to the carotenoid.

scholarly journals Triplet energy transfer in bacterial photosynthetic reaction centres

1998 ◽  
Vol 1365 (3) ◽  
pp. 404-420 ◽  
Author(s):  
A. Angerhofer ◽  
F. Bornhäuser ◽  
V. Aust ◽  
G. Hartwich ◽  
H. Scheer
Keyword(s):  
Energy Transfer ◽  
Triplet Energy ◽  
Reaction Centres ◽  
Triplet Energy Transfer

Thymine Dimerization Induced by Oxidative DNA Lesions and Epigenetic Intermediates via Triplet-Triplet Energy Transfer

2020 ◽  
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angél Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Dna Lesions ◽  
Transient Absorption Spectroscopy ◽  
Triplet Energy ◽  
Pyrimidine Dimers ◽  
Triplet Energy Transfer ◽  
Dna Nucleobases

Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidative lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer the excitation energy to thymine-thymine dyads, inducing the formation of the highly toxic and mutagenic cyclobutane pyrimidine dimers (CPDs). By using steady-state and transient absorption spectroscopy, NMR, HPLC, and theoretical calculations, we quantify the differences in the triplet-triplet energy transfer mediated by ForU and ForC, revealing that the former is much more efficient in delivering the excitation energy and producing the CPD photoproduct. Although significantly slower than ForU, ForC is also able to harm DNA nucleobases and therefore this process has to be taken into account as a viable photosensitization mechanism. The present findings evidence a rich photochemistry crucial to understand DNA photodamage and of potential use in the development of biomarkers and non-conventional photodynamic therapy agents.

Triplet energy transfer in conjugated polymers. II. A polaron theory description addressing the influence of disorder

2008 ◽  
Vol 78 (4) ◽  
Author(s):  
Ivan I. Fishchuk ◽  
Andrey Kadashchuk ◽  
Lekshmi Sudha Devi ◽  
Paul Heremans ◽  
Heinz Bässler ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Conjugated Polymers ◽  
Triplet Energy ◽  
Polaron Theory ◽  
Triplet Energy Transfer

Triplet Energy Transfer Insight in Coordination of Unsaturated Hydrocarbons by d0Bent Metallocenes (Zr, Hf)

2007 ◽  
Vol 111 (43) ◽  
pp. 10928-10937 ◽  
Author(s):  
Galina V. Loukova ◽  
Svetlana E. Starodubova ◽  
Vyatcheslav A. Smirnov
Keyword(s):  
Energy Transfer ◽  
Triplet Energy ◽  
Unsaturated Hydrocarbons ◽  
Triplet Energy Transfer

Triplet-Triplet Energy Transfer from a UV-A Absorber Butylmethoxydibenzoylmethane to UV-B Absorbers

2014 ◽  
Vol 90 (3) ◽  
pp. 511-516 ◽  
Author(s):  
Azusa Kikuchi ◽  
Nozomi Oguchi-Fujiyama ◽  
Kazuyuki Miyazawa ◽  
Mikio Yagi
Keyword(s):  
Energy Transfer ◽  
Triplet Energy ◽  
Triplet Energy Transfer
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