Mechanisms of Activity Loss in PtCo Alloy Systems

2019 ◽  
Vol 11 (1) ◽  
pp. 1247-1257 ◽  
Author(s):  
Sarah C. Ball ◽  
Sarah L. Hudson ◽  
Joe Hei Leung ◽  
Andrea E. Russell ◽  
David Thompsett ◽  
...  
Keyword(s):  
Activity Loss ◽  
Ptco Alloy ◽  
Alloy Systems

scholarly journals Glucuronides Hydrolysis by Intestinal Microbial β-Glucuronidases (GUS) Is Affected by Sampling, Enzyme Preparation, Buffer pH, and Species

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1043
Author(s):  
Christabel Ebuzoeme ◽  
Imoh Etim ◽  
Autumn Ikimi ◽  
Jamie Song ◽  
Ting Du ◽  
...  
Keyword(s):  
Enzyme Preparation ◽  
Reaction System ◽  
Reaction Rates ◽  
Experimental Conditions ◽  
Model Animal ◽  
Fresh Feces ◽  
Time Buffer ◽  
Exogenous Compounds ◽  
Activity Loss ◽  
The Impact

Glucuronides hydrolysis by intestinal microbial β-Glucuronidases (GUS) is an important procedure for many endogenous and exogenous compounds. The purpose of this study is to determine the impact of experimental conditions on glucuronide hydrolysis by intestinal microbial GUS. Standard probe 4-Nitrophenyl β-D-glucopyranoside (pNPG) and a natural glucuronide wogonoside were used as the model compounds. Feces collection time, buffer conditions, interindividual, and species variations were evaluated by incubating the substrates with enzymes. The relative reaction activity of pNPG, reaction rates, and reaction kinetics for wogonoside were calculated. Fresh feces showed the highest hydrolysis activities. Sonication increased total protein yield during enzyme preparation. The pH of the reaction system increased the activity in 0.69–1.32-fold, 2.9–12.9-fold, and 0.28–1.56-fold for mouse, rat, and human at three different concentrations of wogonoside, respectively. The Vmax for wogonoside hydrolysis was 2.37 ± 0.06, 4.48 ± 0.11, and 5.17 ± 0.16 μmol/min/mg and Km was 6.51 ± 0.71, 3.04 ± 0.34, and 0.34 ± 0.047 μM for mouse, rat, and human, respectively. The inter-individual difference was significant (4–6-fold) using inbred rats as the model animal. Fresh feces should be used to avoid activity loss and sonication should be utilized in enzyme preparation to increase hydrolysis activity. The buffer pH should be appropriate according to the species. Inter-individual and species variations were significant.

scholarly journals Post-illumination activity of Bi2WO6 in the dark from the photocatalytic “memory” effect

2021 ◽  
Vol 10 (2) ◽  
pp. 355-367
Author(s):  
Weiyi Yang ◽  
Yan Chen ◽  
Shuang Gao ◽  
Licheng Sang ◽  
Ruoge Tao ◽  
...  
Keyword(s):  
Memory Effect ◽  
Reduction Process ◽  
Production Performance ◽  
Intrinsic Activity ◽  
Light Illumination ◽  
Two Phase ◽  
Photogenerated Electrons ◽  
Composite Photocatalysts ◽  
Pure Phase ◽  
Activity Loss

AbstractPhotocatalysts with the photocatalytic “memory” effect could resolve the intrinsic activity loss of traditional photocatalysts when the light illumination is turned off. Due to the dual requirements of light absorption and energy storage/release functions, most previously reported photocatalysts with the photocatalytic “memory” effect were composite photocatalysts of two phase components, which may lose their performance due to gradually deteriorated interface conditions during their applications. In this work, a simple solvothermal process was developed to synthesize Bi2WO6 microspheres constructed by aggregated nanoflakes. The pure phase Bi2WO6 was found to possess the photocatalytic “memory” effect through the trapping and release of photogenerated electrons by the reversible chemical state change of W component in the (WO4)2− layers. When the illumination was switched off, Bi2WO6 microspheres continuously produced H2O2 in the dark as those trapped photogenerated electrons were gradually released to react with O2 through the two-electron O2 reduction process, resulting in the continuous disinfection of Escherichia coli bacteria in the dark through the photocatalytic “memory” effect. No deterioration of their cycling H2O2 production performance in the dark was observed, which verified their stable photocatalytic “memory” effect.

scholarly journals Self-assembling thermostable chimeras as new platform for arsenic biosensing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rosanna Puopolo ◽  
Ilaria Sorrentino ◽  
Giovanni Gallo ◽  
Alessandra Piscitelli ◽  
Paola Giardina ◽  
...  
Keyword(s):  
Inclusion Bodies ◽  
Association Constant ◽  
Immobilized Enzyme ◽  
Thermus Thermophilus ◽  
Chimeric Protein ◽  
The Self ◽  
Chimeric Proteins ◽  
Self Assembling ◽  
Langmuir Isotherm Model ◽  
Activity Loss

AbstractThe correct immobilization and orientation of enzymes on nanosurfaces is a crucial step either for the realization of biosensors, as well as to guarantee the efficacy of the developed biomaterials. In this work we produced two versions of a chimeric protein, namely ArsC-Vmh2 and Vmh2-ArsC, which combined the self-assembling properties of Vmh2, a hydrophobin from Pleurotus ostreatus, with that of TtArsC, a thermophilic arsenate reductase from Thermus thermophilus; both chimeras were heterologously expressed in Escherichia coli and purified from inclusion bodies. They were characterized for their enzymatic capability to reduce As(V) into As(III), as well as for their immobilization properties on polystyrene and gold in comparison to the native TtArsC. The chimeric proteins immobilized on polystyrene can be reused up to three times and stored for 15 days with 50% of activity loss. Immobilization on gold electrodes showed that both chimeras follow a classic Langmuir isotherm model towards As(III) recognition, with an association constant (KAsIII) between As(III) and the immobilized enzyme, equal to 650 (± 100) L mol−1 for ArsC-Vmh2 and to 1200 (± 300) L mol−1 for Vmh2-ArsC. The results demonstrate that gold-immobilized ArsC-Vmh2 and Vmh2-ArsC can be exploited as electrochemical biosensors to detect As(III).

scholarly journals S-Nitrosothiol Signaling Is involved in Regulating Hydrogen Peroxide Metabolism of Zinc-Stressed Arabidopsis

2019 ◽  
Vol 60 (11) ◽  
pp. 2449-2463 ◽  
Author(s):  
Zs Kolbert ◽  
� Moln�r ◽  
D Ol�h ◽  
G Feigl ◽  
E Horv�th ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Plant Cells ◽  
Thioredoxin Reductase ◽  
Protein S ◽  
Protein Nitration ◽  
Wild Type ◽  
Accumulation Capacity ◽  
Zn Tolerance ◽  
Activity Loss ◽  
New Evidence

Abstract Accumulation of heavy metals such as zinc (Zn) disturbs the metabolism of reactive oxygen (e.g. hydrogen peroxide, H2O2) and nitrogen species (e.g. nitric oxide, NO; S-nitrosoglutathione, GSNO) in plant cells; however, their signal interactions are not well understood. Therefore, this study examines the interplay between H2O2 metabolism and GSNO signaling in Arabidopsis. Comparing the Zn tolerance of the wild type (WT), GSNO reductase (GSNOR) overexpressor 35S::FLAG-GSNOR1 and GSNOR-deficient gsnor1-3, we observed relative Zn tolerance of gsnor1-3, which was not accompanied by altered Zn accumulation capacity. Moreover, in gsnor1-3 plants Zn did not induce NO/S-nitrosothiol (SNO) signaling, possibly due to the enhanced activity of NADPH-dependent thioredoxin reductase. In WT and 35S::FLAG-GSNOR1, GSNOR was inactivated by Zn, and Zn-induced H2O2 is directly involved in the GSNOR activity loss. In WT seedlings, Zn resulted in a slight intensification of protein nitration detected by Western blot and protein S-nitrosation observed by resin-assisted capture of SNO proteins (RSNO-RAC). LC-MS/MS analyses indicate that Zn induces the S-nitrosation of ascorbate peroxidase 1. Our data collectively show that Zn-induced H2O2 may influence its own level, which involves GSNOR inactivation-triggered SNO signaling. These data provide new evidence for the interplay between H2O2 and SNO signaling in Arabidopsis plants affected by metal stress.

Density of Amorphous Alloy Systems (Fe1-xMx)77Si10B13[M=Co, Ni]

1979 ◽  
Vol 18 (10) ◽  
pp. 2023-2024 ◽  
Author(s):  
Mitita Goto ◽  
Hatsuo Tange ◽  
Toshihiko Tokunaga
Keyword(s):  
Amorphous Alloy ◽  
Alloy Systems
Sign in / Sign up

Export Citation Format

Share Document