Charge-Transfer Character of the Low-Energy Chl a Qy Absorption Band in Aggregated Light Harvesting Complexes II

2014 ◽  
Vol 118 (23) ◽  
pp. 6086-6091 ◽  
Author(s):  
Adam Kell ◽  
Ximao Feng ◽  
Chen Lin ◽  
Yiqun Yang ◽  
Jun Li ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Absorption Band ◽  
Light Harvesting ◽  
Low Energy ◽  
Light Harvesting Complexes ◽  
Chl A

scholarly journals Evidence for coherent mixing of excited and charge-transfer states in the major plant light-harvesting antenna, LHCII

2017 ◽  
Vol 19 (34) ◽  
pp. 22877-22886 ◽  
Author(s):  
Charusheela Ramanan ◽  
Marco Ferretti ◽  
Henny van Roon ◽  
Vladimir I. Novoderezhkin ◽  
Rienk van Grondelle
Keyword(s):  
Fourier Transform ◽  
Charge Transfer ◽  
Light Harvesting ◽  
Electronic Spectroscopy ◽  
Low Energy ◽  
Light Harvesting Antenna

2D electronic spectroscopy and Fourier transform maps suggest coherently coupled states at the low-energy edge of the LHCII excitonic manifold.

scholarly journals Reconstitution of light-harvesting complexes and photosystem II cores into galactolipid and phospholipid liposomes.

1985 ◽  
Vol 100 (2) ◽  
pp. 552-557 ◽  
Author(s):  
S G Sprague ◽  
E L Camm ◽  
B R Green ◽  
L A Staehelin
Keyword(s):  
Photosystem Ii ◽  
Light Harvesting ◽  
Freeze Fracture ◽  
Core Material ◽  
Head Group ◽  
Membrane Structures ◽  
Light Harvesting Complexes ◽  
Chl A ◽  
Octyl Glucoside ◽  
Protein Particles

Chlorophyll a/b light-harvesting complexes (chl a/b LHC) and photosystem II (PSII) cores were isolated from an octyl glucoside-containing sucrose gradient after solubilization of barley thylakoid membranes with Triton X-100 and octyl glucoside. No cation precipitation step was necessary to collect the chl a/b LHC. PAGE under mildly denaturing and fully denaturing conditions showed that the chl a/b LHC fraction contained chlorophyll-protein complexes CP27, CP29, and CP64. The PSII core material contained CP43 and CP47, and little contamination by other nonpigmented polypeptides. Freeze-fracture electron microscopy of the chl a/b LHC after reconstitution into digalactosyldiglyceride (DG) or phosphatidylcholine (PC) vesicles showed that the protein particles (approximately 7.5 +/- 1.6 nm) were approximately 99 and 90% randomly dispersed, respectively, in the liposomes. Addition of Mg++ produced particle aggregation and membrane adhesion in chl a/b LHC-DG liposomes in a manner analogous to that described for LHC-PC liposomes. Reconstitution of PSII cores into DG vesicles also produced proteoliposomes with randomly dispersed particles (approximately 7.5 +/- 1.6 nm). In contrast, PSII-PC mixtures formed convoluted networks of tubular membranes that exhibited very few fracture faces. Most of the protein particles (approximately 7.0 +/- 1.5 nm) were seen trapped between, rather than embedded in, the membranes. The interaction between the zwitterionic head group of the phosphatidyl choline and the negatively charged PSII core may be responsible for the unusual membrane structures observed.

scholarly journals Chloroplast SRP43 acts as a chaperone for glutamyl-tRNA reductase, the rate-limiting enzyme in tetrapyrrole biosynthesis

2018 ◽  
Vol 115 (15) ◽  
pp. E3588-E3596 ◽  
Author(s):  
Peng Wang ◽  
Fu-Cheng Liang ◽  
Daniel Wittmann ◽  
Alex Siegel ◽  
Shu-ou Shan ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Signal Recognition Particle ◽  
Direct Interaction ◽  
Tetrapyrrole Biosynthesis ◽  
Light Harvesting Complexes ◽  
Chl A ◽  
Rate Limiting ◽  
Spatiotemporal Coordination ◽  
Substrate Binding Domain ◽  
Chl Biosynthesis

Assembly of light-harvesting complexes requires synchronization of chlorophyll (Chl) biosynthesis with biogenesis of light-harvesting Chl a/b-binding proteins (LHCPs). The chloroplast signal recognition particle (cpSRP) pathway is responsible for transport of nucleus-encoded LHCPs in the stroma of the plastid and their integration into the thylakoid membranes. Correct folding and assembly of LHCPs require the incorporation of Chls, whose biosynthesis must therefore be precisely coordinated with membrane insertion of LHCPs. How the spatiotemporal coordination between the cpSRP machinery and Chl biosynthesis is achieved is poorly understood. In this work, we demonstrate a direct interaction between cpSRP43, the chaperone that mediates LHCP targeting and insertion, and glutamyl-tRNA reductase (GluTR), a rate-limiting enzyme in tetrapyrrole biosynthesis. Concurrent deficiency for cpSRP43 and the GluTR-binding protein (GBP) additively reduces GluTR levels, indicating that cpSRP43 and GBP act nonredundantly to stabilize GluTR. The substrate-binding domain of cpSRP43 binds to the N-terminal region of GluTR, which harbors aggregation-prone motifs, and the chaperone activity of cpSRP43 efficiently prevents aggregation of these regions. Our work thus reveals a function of cpSRP43 in Chl biosynthesis and suggests a striking mechanism for posttranslational coordination of LHCP insertion with Chl biosynthesis.

scholarly journals Complete mapping of energy transfer pathways in the plant light-harvesting complex Lhca4

2020 ◽  
Vol 22 (44) ◽  
pp. 25720-25729
Author(s):  
Martijn Tros ◽  
Vladimir I. Novoderezhkin ◽  
Roberta Croce ◽  
Rienk van Grondelle ◽  
Elisabet Romero
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Light Harvesting ◽  
Electronic Spectroscopy ◽  
Low Energy ◽  
Charge Transfer State ◽  
Two Dimensional ◽  
Light Harvesting Complex ◽  
Complete Mapping ◽  
Transfer State

New insights on Lhca4 from two-dimensional electronic spectroscopy and modelling: population of the charge-transfer state and newly identified low-energy trap.

scholarly journals The Low-Energy Forms of Photosystem I Light-Harvesting Complexes: Spectroscopic Properties and Pigment-Pigment Interaction Characteristics

2007 ◽  
Vol 93 (7) ◽  
pp. 2418-2428 ◽  
Author(s):  
Roberta Croce ◽  
Agnieszka Chojnicka ◽  
Tomas Morosinotto ◽  
Janne A. Ihalainen ◽  
Frank van Mourik ◽  
...  
Keyword(s):  
Photosystem I ◽  
Light Harvesting ◽  
Spectroscopic Properties ◽  
Low Energy ◽  
Light Harvesting Complexes

scholarly journals Strategies to enhance the excitation energy-transfer efficiency in a light-harvesting system using the intra-molecular charge transfer character of carotenoids

2017 ◽  
Vol 198 ◽  
pp. 59-71 ◽  
Author(s):  
Nao Yukihira ◽  
Yuko Sugai ◽  
Masazumi Fujiwara ◽  
Daisuke Kosumi ◽  
Masahiko Iha ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Excitation Energy ◽  
Brown Algae ◽  
Light Harvesting ◽  
Excitation Energy Transfer ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Molecular Charge ◽  
Intra Molecular Charge Transfer

Fucoxanthin is a carotenoid that is mainly found in light-harvesting complexes from brown algae and diatoms. Due to the presence of a carbonyl group attached to polyene chains in polar environments, excitation produces an excited intra-molecular charge transfer. This intra-molecular charge transfer state plays a key role in the highly efficient (∼95%) energy-transfer from fucoxanthin to chlorophyllain the light-harvesting complexes from brown algae. In purple bacterial light-harvesting systems the efficiency of excitation energy-transfer from carotenoids to bacteriochlorophylls depends on the extent of conjugation of the carotenoids. In this study we were successful, for the first time, in incorporating fucoxanthin into a light-harvesting complex 1 from the purple photosynthetic bacterium,Rhodospirillum rubrumG9+ (a carotenoidless strain). Femtosecond pump-probe spectroscopy was applied to this reconstituted light-harvesting complex in order to determine the efficiency of excitation energy-transfer from fucoxanthin to bacteriochlorophyllawhen they are bound to the light-harvesting 1 apo-proteins.

scholarly journals Trifluoromethyl-substituted tetrathiafulvalenes

2015 ◽  
Vol 11 ◽  
pp. 647-658 ◽  
Author(s):  
Olivier Jeannin ◽  
Frédéric Barrière ◽  
Marc Fourmigué
Keyword(s):  
Charge Transfer ◽  
Absorption Band ◽  
Cation Radical ◽  
Radical Cations ◽  
Oxidation Potential ◽  
Low Energy ◽  
Charge Transfer Complexes ◽  
Mesomeric Effect ◽  
Oxidation Potentials ◽  
Homo Lumo

A series of tetrathiafulvalenes functionalized with one or two trifluoromethyl electron-withdrawing groups (EWG) is obtained by phosphite coupling involving CF3-substituted 1,3-dithiole-2-one derivatives. The relative effects of the EWG such as CF3, CO2Me and CN on the TTF core were investigated from a combination of structural, electrochemical, spectrochemical and theoretical investigations. Electrochemical data confirm the good correlations between the first oxidation potential of the TTF derivatives and the σmeta Hammet parameter, thus in the order CO2Me < CF3 < CN, indicating that, in any case, the mesomeric effect of the substituents is limited. Besides, crystal structure determinations show that the deformation of the unsymmetrically substituted dithiole rings, when bearing one, or two different EWG, and attributed to the mesomeric effect of ester or nitrile groups, is not notably modified or counter-balanced by the introduction of a neighboring trifluoromethyl group. DFT calculations confirm these observations and also show that the low energy HOMO–LUMO absorption band found in nitrile or ester-substituted TTFs is not found in TTF-CF3, where, as in TTF itself, the low energy absorption band is essentially attributable to a HOMO→LUMO + 1 transition. Despite relatively high oxidation potentials, these donor molecules with CF3 EWG can be involved in charge transfer complexes or cation radical salts, as reported here for the CF3-subsituted EDT-TTF donor molecule. A neutral charge transfer complex with TCNQ, (EDT-TTF-CF3)2(TCNQ) was isolated and characterized through alternated stacks of EDT-TTF-CF3 dimers and TCNQ in the solid state. A radical cation salt of EDT-TTF-CF3 is also obtained upon electrocrystallisation in the presence of the FeCl4 − anion. In this salt, formulated as (EDT-TTF-CF3)(FeCl4), the (EDT-TTF-CF3)+• radical cations are associated two-by-two into centrosymmetric dyads with a strong pairing of the radical species in a singlet state.

scholarly journals The Origin of the Low-Energy Form of Photosystem I Light-Harvesting Complex Lhca4: Mixing of the Lowest Exciton with a Charge-Transfer State

2009 ◽  
Vol 96 (5) ◽  
pp. L35-L37 ◽  
Author(s):  
Elisabet Romero ◽  
Milena Mozzo ◽  
Ivo H.M. van Stokkum ◽  
Jan P. Dekker ◽  
Rienk van Grondelle ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Photosystem I ◽  
Light Harvesting ◽  
Low Energy ◽  
Charge Transfer State ◽  
Light Harvesting Complex ◽  
A Charge ◽  
Transfer State

Ultrafast excitation dynamics of low energy pigments in reconstituted peripheral light-harvesting complexes of photosystem I

FEBS Letters ◽  
2000 ◽  
Vol 471 (1) ◽  
pp. 89-92 ◽  
Author(s):  
Alexander N. Melkozernov ◽  
Su Lin ◽  
Volkmar H.R. Schmid ◽  
Harald Paulsen ◽  
Gregory W. Schmidt ◽  
...  
Keyword(s):  
Photosystem I ◽  
Light Harvesting ◽  
Low Energy ◽  
Light Harvesting Complexes ◽  
Excitation Dynamics

scholarly journals Blue rhenium tricarbonyl DPPZ complexes – low energy charge-transfer absorption at tissue-penetrating wavelengths

2016 ◽  
Vol 52 (84) ◽  
pp. 12498-12501 ◽  
Author(s):  
M. P. Coogan ◽  
J. A. Platts
Keyword(s):  
Photodynamic Therapy ◽  
Charge Transfer ◽  
Light Harvesting ◽  
Energy Charge ◽  
Low Energy ◽  
Absorption Bands ◽  
Amido Complexes ◽  
Rhenium Tricarbonyl

Re and Mn DPPZ amido complexes show absorption bands with potential for light harvesting and photodynamic therapy.

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