scholarly journals Functioning of quinone acceptors in the reaction center of the green photosynthetic bacteriumChloroflexus aurantiacus

FEBS Letters ◽  
1991 ◽  
Vol 289 (2) ◽  
pp. 179-182 ◽  
Author(s):  
Michael A. Kutuzov ◽  
Mahir D. Mamedov ◽  
Alexey Yu. Semenov ◽  
Vladimir P. Shinkarev ◽  
Michael I. Verkhovsky ◽  
...  
Keyword(s):  
Reaction Center ◽  
Quinone Acceptors

Cytochemical Localization of Polysaccharides in Diplodia Maydis With Thiosemicarbazide : Evaluation of Three Fixatives For Pa:Tsc:Os Reaction

1976 ◽  
Vol 34 ◽  
pp. 48-49 ◽  
Author(s):  
Judith A. Murphy ◽  
Mary R. Thompson ◽  
A.J. Pappelis
Keyword(s):  
Reaction Center ◽  
Osmium Tetroxide ◽  
Periodic Acid ◽  
Cytochemical Localization ◽  
Thin Sections ◽  
Selective Reaction ◽  
Amorphous Character

In an attempt to identify polysaccharide components in thin sections of D. maydis, procedures were employed such that a PAS localization could be carried out. Three different fixatives were evaluated ie. glutaraldehyde, formaldehyde and paraformaldehyde. These were used in conjunction with periodic acid (PA), thiosemicarbazide(TSC), and osmium tetroxide(Os) to localize polysaccharides in V. maydis using a pre-embedded reaction procedure. Polysaccharide localization is based on the oxidation of vic-glycol groups by PA, and the binding of TSC as a selective reaction center for the formation of osmium black. The reaction product is sufficiently electron opaque, insoluble in lipids, not altered when tissue is embedded, and has a fine amorphous character.

Computational Investigation of the Asymmetry in Photosynthetic Reaction Center Models from First Principles

2020 ◽  
Author(s):  
Denis Artiukhin ◽  
Patrick Eschenbach ◽  
Johannes Neugebauer
Keyword(s):  
Spin Density ◽  
Reaction Center ◽  
Density Functional ◽  
Photosynthetic Reaction Center ◽  
Chem Phys ◽  
Molecular Structures ◽  
Error Characteristic ◽  
Molecular Systems ◽  
Density Distributions ◽  
The Asymmetry

We present a computational analysis of the asymmetry in reaction center models of photosystem I, photosystem II, and bacteria from <i>Synechococcus elongatus</i>, <i>Thermococcus vulcanus</i>, and <i>Rhodobacter sphaeroides</i>, respectively. The recently developed FDE-diab methodology [J. Chem. Phys., 148 (2018), 214104] allowed us to effectively avoid the spin-density overdelocalization error characteristic for standard Kohn–Sham Density Functional Theory and to reliably calculate spin-density distributions and electronic couplings for a number of molecular systems ranging from dimeric models in vacuum to large protein including up to about 2000 atoms. The calculated spin densities showed a good agreement with available experimental results and were used to validate reaction center models reported in the literature. We demonstrated that the applied theoretical approach is very sensitive to changes in molecular structures and relative orientation of molecules. This makes FDE-diab a valuable tool for electronic structure calculations of large photosynthetic models effectively complementing the existing experimental techniques.

The effect of acceptor modification upon the synthesis of dinucleoside phosphates catalyzed by non-specific ribonucleases of Penicillium claviforme

1979 ◽  
Vol 44 (2) ◽  
pp. 613-625 ◽  
Author(s):  
Valentina I. Gulyaeva ◽  
Antonín Holý
Keyword(s):  
Reaction Center ◽  
Hydroxy Group ◽  
Pyrimidine Ring ◽  
Phosphate Group ◽  
Mutual Orientation ◽  
Acceptor Molecule ◽  
Heterocyclic Base ◽  
Sugar Moiety ◽  
Cyclic Phosphate ◽  
Penicillium Claviforme

The present paper studies the effect of the modification of heterocyclic base, sugar moiety and the presence of phosphate group on the nucleoside acceptors in the synthesis of dinucleoside phosphates from adenosine 2',3'-cyclic phosphate as donor, catalyzed by nonspecific acidic extracellular and intracellular ribonucleases from Penicillium claviforme. The enzyme binds specifically the acceptor molecule, preferring cytosine nucleosides. It requires the presence of the whole sugar moiety, an exact mutual orientation of the heterocyclic base and the reaction center (5'-hydroxy group), and a suitable conformation of the acceptor molecule. The enzyme-acceptor bond is homochiral and the presence of the N3-H group in the pyrimidine ring is important. The reaction between the donor and the acceptor is bimolecular and is competitively inhibited by some purine nucleosides.

High degradation efficiency of sulfamethazine with the dual-reaction-center Fe-Mn-SiO2 Fenton-like nanocatalyst in a wide pH range

2021 ◽  
Author(s):  
Manoj Kumar Panjwani ◽  
Qing Wang ◽  
Yueming Ma ◽  
Yuxuan Lin ◽  
Feng Xiao ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Reaction Center ◽  
Degradation Efficiency ◽  
Heterogeneous Fenton ◽  
Wide Ph Range ◽  
Ph Range

The development of a heterogeneous Fenton-like catalyst, possessing high degradation efficiency in a wide pH range, is crucial for wastewater treatment. The Fe-Mn-SiO2 catalyst was designed, and prepared by a...

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