Proton uptake behaviors of organic and inorganic matters in biochars prepared under different pyrolytic temperatures

2020 ◽  
Vol 746 ◽  
pp. 140853 ◽  
Author(s):  
Xin Xiao ◽  
Zaiming Chen ◽  
Baoliang Chen
Keyword(s):  
Proton Uptake

scholarly journals Effects of NiO addition on sintering and proton uptake of Ba(Zr,Ce,Y)O3-δ

2021 ◽  
Author(s):  
Yuanye Huang ◽  
Rotraut Merkle ◽  
Joachim Maier
Keyword(s):  
Solid State ◽  
Complex Nature ◽  
Reactive Sintering ◽  
Sintering Aid ◽  
Proton Conducting ◽  
Proton Uptake ◽  
Sintering Method

The effects of 0.125-0.2 wt% NiO added as sintering aid for highly refractory Ba(Zr,Ce,Y)O3-δ proton conducting ceramics are investigated. The complex nature of the solid state reactive sintering method shows...

Effects of Difenzoquat on Photoreactions and Respiration in Wheat (Triticum aestivum) and Wild Oat (Avena fatua)

Weed Science ◽  
1983 ◽  
Vol 31 (5) ◽  
pp. 693-699 ◽  
Author(s):  
Blaik P. Halling ◽  
Richard Behrens
Keyword(s):  
Triticum Aestivum ◽  
Electron Transport ◽  
Electron Acceptor ◽  
Photosynthetic Electron Transport ◽  
Significant Inhibition ◽  
Avena Fatua ◽  
Wild Oat ◽  
Leaf Chlorosis ◽  
Acceptor Activity ◽  
Proton Uptake

Experiments were conducted with isolated protoplasts of wild oat (Avena fatuaL. # AVEFA) and isolated chloroplasts of wild oat and wheat (Triticum aestivumL.), to determine if the methyl sulfate salt of difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium) might influence photoreactions in these species. Difenzoquat did not affect CO2fixation, uncoupled electron transport, or proton uptake. At concentrations of 0.5 mM and 1 mM, difenzoquat caused a slight, but statistically significant, inhibition of photophosphorylation. Experiments assaying coupled electron transport indicated that inhibition of photophosphorylation occurred not through uncoupling, but by an energy-transfer inhibition. This same effect was observed in isolated mitocondria of both species, with about 50% inhibition of state 3 respiration rates occurring with 10 μM difenzoquat. However, no important differentials were observed in the relative susceptibilities of wheat and wild oat mitochondria. Difenzoquat also functioned as a weak autooxidizing electron acceptor in photosynthetic electron transport. Therefore, difenzoquat-induced leaf chlorosis and necrosis may result from a bipyridilium-type electron acceptor activity if sufficient herbicide is absorbed.

scholarly journals Mutation of a single residue in the ba3 oxidase specifically impairs protonation of the pump site

2015 ◽  
Vol 112 (11) ◽  
pp. 3397-3402 ◽  
Author(s):  
Christoph von Ballmoos ◽  
Nathalie Gonska ◽  
Peter Lachmann ◽  
Robert B. Gennis ◽  
Pia Ädelroth ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Time Constant ◽  
Thermus Thermophilus ◽  
Proton Translocation ◽  
Proton Pumping ◽  
Wild Type ◽  
Structural Variant ◽  
In The Wild ◽  
Membrane Bound ◽  
Proton Uptake

The ba3-type cytochrome c oxidase from Thermus thermophilus is a membrane-bound protein complex that couples electron transfer to O2 to proton translocation across the membrane. To elucidate the mechanism of the redox-driven proton pumping, we investigated the kinetics of electron and proton transfer in a structural variant of the ba3 oxidase where a putative “pump site” was modified by replacement of Asp372 by Ile. In this structural variant, proton pumping was uncoupled from internal electron transfer and O2 reduction. The results from our studies show that proton uptake to the pump site (time constant ∼65 μs in the wild-type cytochrome c oxidase) was impaired in the Asp372Ile variant. Furthermore, a reaction step that in the wild-type cytochrome c oxidase is linked to simultaneous proton uptake and release with a time constant of ∼1.2 ms was slowed to ∼8.4 ms, and in Asp372Ile was only associated with proton uptake to the catalytic site. These data identify reaction steps that are associated with protonation and deprotonation of the pump site, and point to the area around Asp372 as the location of this site in the ba3 cytochrome c oxidase.

scholarly journals Molecular basis of proton uptake in single and double mutants of cytochromecoxidase

2011 ◽  
Vol 23 (23) ◽  
pp. 234102 ◽  
Author(s):  
Rowan M Henry ◽  
David Caplan ◽  
Elisa Fadda ◽  
Régis Pomès
Keyword(s):  
Molecular Basis ◽  
Proton Uptake

Inhibition of oxygen evolution by ivalin

1994 ◽  
Vol 72 (2) ◽  
pp. 177-181 ◽  
Author(s):  
Ernesto Bernal-Morales ◽  
Alfonso Romo De Vivar ◽  
Bertha Sanchez ◽  
Martha Aguilar ◽  
Blas Lotina-Hennsen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Sesquiterpene Lactone ◽  
Oxygen Evolution ◽  
Electron Flow ◽  
Atp Synthesis ◽  
Naturally Occurring ◽  
Transport Inhibitor ◽  
Proton Uptake ◽  
Key Words Oxygen

The inhibition of ATP synthesis, proton uptake, and electron transport (basal, phosphorylating, and uncoupled) from water to methylviologen by ivalin (a naturally occurring sesquiterpene lactone in Zaluzania triloba and Iva microcephala) indicates that it acts as electron transport inhibitor. Since photosystem I and electron transport from DPC to QA were not affected, while the electron flow of uncoupled photosystem II from H2O to DAD and from water to silicomolybdate was inhibited, we concluded that the site of inhibition of ivalin is located at the oxygen evolution level. Key words: oxygen evolution, ivalin, photosynthesis, sesquiterpene lactone.

scholarly journals Breaking the Carboxyl Rule

2013 ◽  
Vol 288 (29) ◽  
pp. 21254-21265 ◽  
Author(s):  
Sergei P. Balashov ◽  
Lada E. Petrovskaya ◽  
Eleonora S. Imasheva ◽  
Evgeniy P. Lukashev ◽  
Andrei K. Dioumaev ◽  
...  
Keyword(s):  
Schiff Base ◽  
Water Molecule ◽  
Proton Pump ◽  
Rate Constants ◽  
Proton Donor ◽  
Carboxyl Group ◽  
Amino Group ◽  
Wild Type ◽  
Fast Phase ◽  
Proton Uptake

A lysine instead of the usual carboxyl group is in place of the internal proton donor to the retinal Schiff base in the light-driven proton pump of Exiguobacterium sibiricum (ESR). The involvement of this lysine in proton transfer is indicated by the finding that its substitution with alanine or other residues slows reprotonation of the Schiff base (decay of the M intermediate) by more than 2 orders of magnitude. In these mutants, the rate constant of the M decay linearly decreases with a decrease in proton concentration, as expected if reprotonation is limited by the uptake of a proton from the bulk. In wild type ESR, M decay is biphasic, and the rate constants are nearly pH-independent between pH 6 and 9. Proton uptake occurs after M formation but before M decay, which is especially evident in D2O and at high pH. Proton uptake is biphasic; the amplitude of the fast phase decreases with a pKa of 8.5 ± 0.3, which reflects the pKa of the donor during proton uptake. Similarly, the fraction of the faster component of M decay decreases and the slower one increases, with a pKa of 8.1 ± 0.2. The data therefore suggest that the reprotonation of the Schiff base in ESR is preceded by transient protonation of an initially unprotonated donor, which is probably the ϵ-amino group of Lys-96 or a water molecule in its vicinity, and it facilitates proton delivery from the bulk to the reaction center of the protein.

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