Prolonged incubation with low concentrations of mercury alters energy transfer and chlorophyll (Chl) a protein complexes in Synechococcus 6301: changes in Chl a absorption and emission characteristics and loss of the F695 emission band

BioMetals ◽  
1995 ◽  
Vol 8 (3) ◽  
Author(s):  
S.D.S. Murthy ◽  
N. Mohanty ◽  
Prasanna Mohanty
Keyword(s):  
Energy Transfer ◽  
Emission Band ◽  
Protein Complexes ◽  
Emission Characteristics ◽  
Prolonged Incubation ◽  
Absorption And Emission ◽  
Chl A ◽  
Low Concentrations ◽  
Synechococcus 6301

scholarly journals The effects of Triton X-100 and n-octyl β-d-glucopyranoside on energy transfer in photosynthetic membranes

1984 ◽  
Vol 224 (3) ◽  
pp. 989-993 ◽  
Author(s):  
D J Murphy ◽  
I E Woodrow
Keyword(s):  
Energy Transfer ◽  
Protein Complexes ◽  
Fluorescence Emission ◽  
Emission Peak ◽  
Wavelength Shift ◽  
Emission Characteristics ◽  
Ionic Detergents ◽  
Reversible Dissociation ◽  
Pigment Protein Complexes ◽  
Triton X

The effects of the non-ionic detergents Triton X-100 and n-octyl beta-D-glucopyranoside on energy transfer between pigment-protein complexes of Pisum sativum thylakoids were investigated. This was done by monitoring the 77K fluorescence-emission characteristics of stacked and unstacked thylakoids exposed to a range of detergent concentrations. At sub-critical micellar concentrations, the detergents had little effect, whereas above these concentrations they caused increases of up to 20-fold in short-wavelength fluorescence intensity and a shift in its maximum wavelength from 685 to 680 nm. Fluorescence-emission intensities at 695 and 735 nm were relatively unaffected by detergent treatments, although Triton X-100 caused a wavelength shift in the emission peak from 735 to 728 nm. The results are discussed in terms of reversible dissociation of pigment-protein complexes induced by mild detergent solubilization and the consequent cessation of inter-complex energy transfer.

Tracing absorption and emission characteristics of halogen-bonded ion pairs involving halogenated imidazolium species

2021 ◽  
Vol 23 (12) ◽  
pp. 7480-7494
Author(s):  
Sarah Karbalaei Khani ◽  
Bastian Geissler ◽  
Elric Engelage ◽  
Patrick Nuernberger ◽  
Christof Hättig
Keyword(s):  
Ion Pairs ◽  
Ion Pairing ◽  
Emission Characteristics ◽  
Absorption And Emission ◽  
Spectroscopic Signatures

Spectroscopic signatures of ion-pairing are identified by variation of counterion and substitution and comparison with theory.

Structural basis for blue-green light harvesting and energy dissipation in diatoms

Science ◽  
2019 ◽  
Vol 363 (6427) ◽  
pp. eaav0365 ◽  
Author(s):  
Wenda Wang ◽  
Long-Jiang Yu ◽  
Caizhe Xu ◽  
Takashi Tomizaki ◽  
Songhao Zhao ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Phaeodactylum Tricornutum ◽  
Light Harvesting ◽  
Green Light ◽  
Marine Diatom ◽  
Structural Basis ◽  
Aquatic Environments ◽  
Efficient Energy Transfer ◽  
Chl A ◽  
Photosynthetic Organisms

Diatoms are abundant photosynthetic organisms in aquatic environments and contribute 40% of its primary productivity. An important factor that contributes to the success of diatoms is their fucoxanthin chlorophyll a/c-binding proteins (FCPs), which have exceptional light-harvesting and photoprotection capabilities. Here, we report the crystal structure of an FCP from the marine diatom Phaeodactylum tricornutum, which reveals the binding of seven chlorophylls (Chls) a, two Chls c, seven fucoxanthins (Fxs), and probably one diadinoxanthin within the protein scaffold. Efficient energy transfer pathways can be found between Chl a and c, and each Fx is surrounded by Chls, enabling the energy transfer and quenching via Fx highly efficient. The structure provides a basis for elucidating the mechanisms of blue-green light harvesting, energy transfer, and dissipation in diatoms.

Un exemple d'isomérisation radicalaire en chaînes: la photoinduction de l'isomérisation cis–trans de la pentène-3 one-2

1977 ◽  
Vol 55 (22) ◽  
pp. 3915-3926 ◽  
Author(s):  
Armel Rioual ◽  
André Deflandre ◽  
Jacques Lemaire
Keyword(s):  
Energy Transfer ◽  
Quantum Yields ◽  
Unsaturated Ketone ◽  
Chain Process ◽  
Triplet Energy ◽  
Low Concentrations ◽  
Energy Transfers ◽  
Donor And Acceptor ◽  
A Chain ◽  
Triplet Energy Transfer

Mechanisms of the photosensitized cis–trans photoisomerization of 3-penten-2-one which do not imply only classical triplet–triplet energy transfer are proposed; they are based upon measurements of the variations of initial quantum yields of isomerization with the initial donor and acceptor concentrations, the wavelength of excitation, and the nature of the donor and of the solvent. Carbonyl donors (acetophenone, benzophenone, acetone) induce a radical isomerization by a chain process in reducing solvents; the example of acetophenone is specially interesting. In solvents in which the donor is not photoreduced (as benzene or CCl4) classical triplet–triplet energy transfers occur. Sensitization with aromatic donors (benzene, mesitylene) proceeds through triplet–triplet energy transfer at low concentrations of the acceptor. At higher concentrations of acceptor, an exciplex is formed between the ketone and the aromatic in its singlet excited state; this exciplex is deactivated by dissociation and by causing the isomerization of the α,β-unsaturated ketone.

scholarly journals Functional dissection of the CD21/CD19/TAPA-1/Leu-13 complex of B lymphocytes.

1993 ◽  
Vol 178 (4) ◽  
pp. 1407-1417 ◽  
Author(s):  
A K Matsumoto ◽  
D R Martin ◽  
R H Carter ◽  
L B Klickstein ◽  
J M Ahearn ◽  
...  
Keyword(s):  
B Lymphocytes ◽  
Protein Complexes ◽  
Pi3 Kinase ◽  
Free Calcium ◽  
Wild Type ◽  
Extracellular Domains ◽  
Membrane Immunoglobulin ◽  
Low Concentrations ◽  
Cellular Aggregation ◽  
Membrane Protein Complexes

The CD21/CD19/TAPA-1 complex of B lymphocytes amplifies signal transduction through membrane immunoglobulin (mIg), recruits phosphatidylinositol 3-kinase (PI3-kinase), and induces homotypic cellular aggregation. The complex is unique among known membrane protein complexes of the immune system because its components represent different protein families, and can be expressed individually. By constructing chimeric molecules replacing the extracellular, transmembrane, and cytoplasmic regions of CD19 and CD21 with those of HLA-A2 and CD4, we have determined that CD19 and TAPA-1 interact through their extracellular domains, CD19 and CD21 through their extracellular and transmembrane domains, and, in a separate complex, CD21 and CD35 through their extracellular domains. A chimeric form of CD19 that does not interact with CD21 or TAPA-1 was expressed in Daudi B lymphoblastoid cells and was shown to replicate two functions of wild-type CD19 contained within the complex: synergistic interaction with mIgM to increase intracellular free calcium and tyrosine phosphorylation and association with the p85 subunit of PI3-kinase after ligation of mIgM. The chimeric CD19 lacked the capacity of the wild-type CD19 to induce homotypic cellular aggregation, a function of the complex that can be ascribed to the TAPA-1 component. The CD21/CD19/TAPA-1 complex brings together independently functioning subunits to enable the B cell to respond to low concentrations of antigen.

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