scholarly journals Distribution and self-organization of photosynthetic pigments in micelles: implication for the assembly of light-harvesting complexes and reaction centers in the photosynthetic membrane.

1990 ◽  
Vol 87 (14) ◽  
pp. 5430-5434 ◽  
Author(s):  
A. Scherz ◽  
V. Rosenbach-Belkin ◽  
J. R. Fisher
Keyword(s):  
Photosynthetic Pigments ◽  
Light Harvesting ◽  
Reaction Centers ◽  
Self Organization ◽  
Photosynthetic Membrane ◽  
Light Harvesting Complexes

scholarly journals Photosynthetic Light-Harvesting (Antenna) Complexes—Structures and Functions

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3378
Author(s):  
Heiko Lokstein ◽  
Gernot Renger ◽  
Jan Götze
Keyword(s):  
Cross Sections ◽  
Light Harvesting ◽  
Photosynthetic Apparatus ◽  
Structural Diversity ◽  
Reaction Centers ◽  
Photosynthetic Membrane ◽  
Light Harvesting Complexes ◽  
Tentative Explanation ◽  
Light Harvesting Antenna ◽  
Photosynthetic Antenna

Chlorophylls and bacteriochlorophylls, together with carotenoids, serve, noncovalently bound to specific apoproteins, as principal light-harvesting and energy-transforming pigments in photosynthetic organisms. In recent years, enormous progress has been achieved in the elucidation of structures and functions of light-harvesting (antenna) complexes, photosynthetic reaction centers and even entire photosystems. It is becoming increasingly clear that light-harvesting complexes not only serve to enlarge the absorption cross sections of the respective reaction centers but are vitally important in short- and long-term adaptation of the photosynthetic apparatus and regulation of the energy-transforming processes in response to external and internal conditions. Thus, the wide variety of structural diversity in photosynthetic antenna “designs” becomes conceivable. It is, however, common for LHCs to form trimeric (or multiples thereof) structures. We propose a simple, tentative explanation of the trimer issue, based on the 2D world created by photosynthetic membrane systems.

scholarly journals The terminal phycobilisome emitter, LCM: A light-harvesting pigment with a phytochrome chromophore

2015 ◽  
Vol 112 (52) ◽  
pp. 15880-15885 ◽  
Author(s):  
Kun Tang ◽  
Wen-Long Ding ◽  
Astrid Höppner ◽  
Cheng Zhao ◽  
Lun Zhang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Transient Absorption ◽  
Light Harvesting ◽  
Reaction Centers ◽  
Protein Fold ◽  
Light Harvesting Complexes ◽  
Exciton Coupling ◽  
Femtosecond Transient Absorption ◽  
Orange Carotenoid Protein ◽  
Sensory Photoreceptors

Photosynthesis relies on energy transfer from light-harvesting complexes to reaction centers. Phycobilisomes, the light-harvesting antennas in cyanobacteria and red algae, attach to the membrane via the multidomain core-membrane linker, LCM. The chromophore domain of LCM forms a bottleneck for funneling the harvested energy either productively to reaction centers or, in case of light overload, to quenchers like orange carotenoid protein (OCP) that prevent photodamage. The crystal structure of the solubly modified chromophore domain from Nostoc sp. PCC7120 was resolved at 2.2 Å. Although its protein fold is similar to the protein folds of phycobiliproteins, the phycocyanobilin (PCB) chromophore adopts ZZZssa geometry, which is unknown among phycobiliproteins but characteristic for sensory photoreceptors (phytochromes and cyanobacteriochromes). However, chromophore photoisomerization is inhibited in LCM by tight packing. The ZZZssa geometry of the chromophore and π-π stacking with a neighboring Trp account for the functionally relevant extreme spectral red shift of LCM. Exciton coupling is excluded by the large distance between two PCBs in a homodimer and by preservation of the spectral features in monomers. The structure also indicates a distinct flexibility that could be involved in quenching. The conclusions from the crystal structure are supported by femtosecond transient absorption spectra in solution.

scholarly journals J-aggregates of amphiphilic cyanine dyes: Self-organization of artificial light harvesting complexes

2006 ◽  
Vol 2006 ◽  
pp. 1-21 ◽  
Author(s):  
Stefan Kirstein ◽  
Siegfried Daehne
Keyword(s):  
Structural Model ◽  
Light Harvesting ◽  
Optical Spectra ◽  
Cyanine Dye ◽  
Structural Motif ◽  
Self Organization ◽  
Artificial Light ◽  
Light Harvesting Complexes ◽  
Unequal Distribution ◽  
J Aggregates

The simultaneous chemical linkage of cyanine dye chromophores with both hydrophobic and hydrophilic substituents leads to a new type of amphiphilic molecules with the ability of spontaneous self-organization into highly ordered aggregates of various structures and morphologies. These aggregates carry the outstanding optical properties of J-aggregates, namely, efficient exciton coupling and fast exciton energy migration, which are essential for the build up of artificial light harvesting systems. The morphology of the aggregates depends sensitively on the molecular structure of the chemical substituents of the dye chromophore. Accordingly, lamellar ribbon-like structures, vesicles , tubes, and bundles of tubes are found depending on the dyes and the structure can further be altered by addition of surfactants, alcohols, or other additives. Altogether the tubular structure is the most noticeable structural motif of these types of J-aggregates. The optical spectra are characterized in general by a complex exciton spectrum which is composed of several electronic transitions. The spectrum is red-shifted as a total with respect to the monomer absorption and exhibits resonance fluorescence from the lowest energy transition. For the tubular structures, the optical spectra can be related to a structural model. Although the molecules itself are strictly achiral, a pronounced circular dichroism (CD) is observed for the tubular aggregates and explained by unequal distribution of left- and right-handed helicity of the tubes. Photo-induced electron transfer (PET) reactions from the dye aggregates to electron acceptor molecules lead to superquenching which proves the delocalization of the excitation. This property is used to synthesize metal nanoparticles on the aggregate surface by photo-induced reduction of metal ions.

scholarly journals Light’s interaction with pigments in chloroplasts: The murburn perspective, with special relevance to carotenoids

2020 ◽  
Author(s):  
Kelath Murali Manoj ◽  
Afsal Manekkathodi
Keyword(s):  
Light Harvesting ◽  
Reaction Centers ◽  
Oxygenic Photosynthesis ◽  
Physiological Data ◽  
Light Harvesting Complexes ◽  
Light Reaction ◽  
Historical Perspectives ◽  
Electron Emitters ◽  
Theoretical Foundations ◽  
Special Relevance

The prevailing understanding on photolytic photophosphorylation, the light reaction of oxygenic photosynthesis, considers the vast majority of the diverse pigments, chlorophyll binding proteins (CBPs) and light harvesting complexes (LHCs) as photon-energy relaying facets; only the two photosystems’ (PS) reaction centers’ chlorophyll a couplets are deemed to serve as photo-excitable electron emitters. Highlighting the historical perspectives involved, we present reasons why this conventional perception is unmet by theoretical foundations, unsupported by molecular awareness on the various pigments and unverified by physiological data available on chloroplasts. Further, we propose a simple diffusible reactive oxygen species (DROS)-based mechanism for correlating the functions of various light harvesting LHCs and CBPs with the reaction centers of PS I & II.

Enhanced Photocurrent Generation by Photosynthetic Bacterial Reaction Centers through Molecular Relays, Light-Harvesting Complexes, and Direct Protein–Gold Interactions

Langmuir ◽  
2011 ◽  
Vol 27 (16) ◽  
pp. 10282-10294 ◽  
Author(s):  
Mart-Jan den Hollander ◽  
J. Gerhard Magis ◽  
Philipp Fuchsenberger ◽  
Thijs J. Aartsma ◽  
Michael R. Jones ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Reaction Centers ◽  
Light Harvesting Complexes ◽  
Photocurrent Generation ◽  
Bacterial Reaction Centers

scholarly journals Interference lithographic nanopatterning of plant and bacterial light-harvesting complexes on gold substrates

2015 ◽  
Vol 5 (4) ◽  
pp. 20150005 ◽  
Author(s):  
Samson Patole ◽  
Cvetelin Vasilev ◽  
Osama El-Zubir ◽  
Lin Wang ◽  
Matthew P. Johnson ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Nitrilotriacetic Acid ◽  
Surface Topology ◽  
Photosynthetic Membrane ◽  
Light Harvesting Complexes ◽  
Amine Functionalized ◽  
Dual Beam ◽  
Assembled Monolayers

We describe a facile approach for nanopatterning of photosynthetic light-harvesting complexes over macroscopic areas, and use optical spectroscopy to demonstrate retention of native properties by both site-specifically and non-specifically attached photosynthetic membrane proteins. A Lloyd's mirror dual-beam interferometer was used to expose self-assembled monolayers of amine-terminated alkylthiolates on gold to laser irradiation. Following exposure, photo-oxidized adsorbates were replaced by oligo(ethylene glycol) terminated thiols, and the remaining intact amine-functionalized regions were used for attachment of the major light-harvesting chlorophyll–protein complex from plants, LHCII. These amine patterns could be derivatized with nitrilotriacetic acid (NTA), so that polyhistidine-tagged bacteriochlorophyll–protein complexes from phototrophic bacteria could be attached with a defined surface orientation. By varying parameters such as the angle between the interfering beams and the laser irradiation dose, it was possible to vary the period and widths of NTA and amine-functionalized lines on the surfaces; periods varied from 1200 to 240 nm and linewidths as small as 60 nm ( λ /4) were achieved. This level of control over the surface chemistry was reflected in the surface topology of the protein nanostructures imaged by atomic force microscopy; fluorescence imaging and spectral measurements demonstrated that the surface-attached proteins had retained their native functionality.

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