Metal ion induced allosteric transition in the catalytic activity of an artificial phosphodiesterase

2008 ◽  
Vol 6 (3) ◽  
pp. 493-499 ◽  
Author(s):  
Shinji Takebayashi ◽  
Seiji Shinkai ◽  
Masato Ikeda ◽  
Masayuki Takeuchi
Keyword(s):  
Catalytic Activity ◽  
Metal Ion ◽  
Allosteric Transition

scholarly journals Co3O4/TiO2 hetero-structure for methyl orange dye degradation

2018 ◽  
Vol 79 (5) ◽  
pp. 947-957 ◽  
Author(s):  
Mahabubur Chowdhury ◽  
Sarah Kapinga ◽  
Franscious Cummings ◽  
Veruscha Fester
Keyword(s):  
Catalytic Activity ◽  
Methyl Orange ◽  
Environmental Remediation ◽  
Metal Ion ◽  
Dye Degradation ◽  
Lattice Structure ◽  
Host Lattice ◽  
Commercial Application ◽  
Potential Candidate ◽  
Methyl Orange Degradation

Abstract Advanced oxidation processes based on sulphate radical generated by peroxymonosulphate (PMS) activation is a promising area for environmental remediation. One of the biggest drawbacks of heterogeneous PMS activation is catalyst instability and metal ion leaching. In this study, a simple organic binder mediated route was explored to substitute Ti4+ ions into the Co3O4 host lattice structure to create a Co-O-Ti bond to minimise cobalt leaching during methyl orange degradation. The catalyst was characterised by X-ray diffraction, and scanning and transmission electron microscopy. The as-prepared catalysts with Co3O4:TiO2 ratio of 70:30 exhibited minimal leaching (0.9 mg/L) compared to other ratios studied. However, the pristine Co3O4 exhibited highest catalytic activity (rate constant = 0.41 min−1) and leaching (26.7 mg/L) compared to composite material (70:30 Co3O4:TiO2). Interestingly, the morphology of the composite and leaching of Co2+ ions were found to be temperature dependent, as an optimum temperature ensured strong Co-O-Ti bond for prevention of Co2+ leaching. The classical quenching test was utilised to determine the presence and role of radical species on methyl orange degradation. The fabricated catalyst also exhibited good catalytic activity in degrading mixed dyes and good recyclability, making it a potential candidate for commercial application.

scholarly journals Volcano-Type Correlation between Particle Size and Catalytic Activity on Hydrodechlorination catalyzed by AuPd Nanoalloy

2020 ◽  
Author(s):  
Yuta Uetake ◽  
Sachi Mouri ◽  
Setsiri Haesuwannakij ◽  
Kazu Okumura ◽  
Hidehiro Sakurai
Keyword(s):  
Catalytic Activity ◽  
Metal Ion ◽  
Mixing Time ◽  
Metal Nanoparticle ◽  
Edge Structure ◽  
X Ray ◽  
Rate Determining Step ◽  
Transmission Electron ◽  
Random Alloy ◽  
X Ray Absorption

<div>Although changing the size of metal nanoparticle (NP) is a reasonable way to tune and/or enhance their catalytic activity, size-selective preparation of NP possessing random-alloy morphology has been challenging because of the differences in the ionization potential of each metal ion. This study demonstrates a time-controlled aggregation–stabilization method for a size-selective preparation of random alloy NPs composed of Au and Pd, which are stabilized by poly(<i>N</i>-vinyl-2-pyrrolidone) (PVP). By adjusting the mixing time in the presence of a small amount of PVP, the aggregation was induced to produce AuPd:PVP with sizes ranging between 1.2 and 8.2 nm at approximately 1 nm intervals. Transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and extended x-ray absorption fine structure (EXAFS) analyses clearly indicated the formation of various sizes of AuPd nanoalloys with almost the same morphology, and size-dependent catalytic activity was observed when hydrodechlorination of 4-choroanisole was performed using 2-propanol as a reducing agent. AuPd:PVP with a size of 3.1 nm exhibited the highest catalytic activity. A comparison of the absorption edges on x-ray absorption near edge structure (XANES) spectra suggested that the electronic state of the Au and Pd species correlated with their catalytic activity, presumably affecting the rate-determining step.</div><div> </div>

Effects of Vanadate on the Molybdoproteins Xanthine Oxidase and Nitrate Reductase: Kinetic Evidence for Multiple Site Interaction

1980 ◽  
Vol 35 (9-10) ◽  
pp. 702-707 ◽  
Author(s):  
Candadai S. Ramadoss
Keyword(s):  
Catalytic Activity ◽  
Nitrate Reductase ◽  
Xanthine Oxidase ◽  
Oxidase Activity ◽  
Metal Ion ◽  
Nadh Oxidase ◽  
Multiple Site ◽  
Vanadate Inhibition ◽  
Nadh Oxidase Activity

Abstract The inhibition of the activity of xanthine oxidase by vanadate was strikingly similar to vanadate inhibition of another molybdoprotein nitrate reductase. Although the main catalytic activity of both enzymes was inhibited, the partial NADH oxidase activity associated with these enzymes was stimulated several fold. It appears that the metal ion binds at multiple site in both enzymes. In the absence of any enzymes a combination of vanadium (V) and molybdenum (V) in air was found to oxide NADH rapidly.

scholarly journals THE METAL COMPLEXES OF NOVEL SCHIFF BASE CONTAINING ISATIN: CHARACTERIZATION, ANTIMICROBIAL, ANTIOXIDANT AND CATALYTIC ACTIVITY STUDY

2019 ◽  
pp. 206-210
Author(s):  
VAIRALAKSHMI M ◽  
PRINCESS R ◽  
JOHNSON RAJA S
Keyword(s):  
Catalytic Activity ◽  
Metal Complexes ◽  
1H Nmr ◽  
Metal Ion ◽  
Analytical Data ◽  
Free Ligand ◽  
Molar Conductance ◽  
Diffusion Method ◽  
Spectral Studies ◽  
Standard Drug

Objectives: The aim of our work was to synthesize novel mixed ligand-metal complexes and evaluation of antimicrobial, antioxidant assay, and analysis of catalytic oxidation of cyclohexane. Methods: The complexes were characterized by means of various physicochemical techniques such as elemental analysis, molar conductance, magnetic susceptibility, infrared (IR), electronic absorption, 1H NMR (proton magnetic resonance), and mass spectral studies. The antimicrobial screening study was done by disc diffusion method. The catalytic activity of the complexes was observed in the oxidation of cyclohexane using eco-friendly hydrogen peroxide as oxidant. Results: On comparing the 1H NMR and IR spectral data of free ligand and its complexes, it was found to be azomethine (CH=N) proton which is formed in the free ligand. During complexation, the azomethine proton is coordinated to the metal ion and the phenolic oxygen is coordinated to the metal ion by deprotonation. The analytical data and mass spectra of the ligand and the complexes confirm the stoichiometry of metal complexes as being of the (MLY)Cl type and the metal to ligand ratio is 1:1. The antimicrobial, antioxidant, and catalytic potential were evaluated and the result shows the better activity of the complexes than the ligand. Conclusion: It was found to be copper(II) and zinc(II) complexes which are effective against all the bacteria when compared to standard drug streptomycin. Copper(II) complex was found to be effective antibacterial agent against Aspergillus niger and Aspergillus flavus in comparison to the standard drug Nystatin. The zinc complex exhibited good catalytic activity.

scholarly journals A modified ionic liquid clay to remove heavy metals from water: investigating its catalytic activity

2019 ◽  
Vol 17 (4) ◽  
pp. 2043-2058
Author(s):  
S. Kakaei ◽  
E. S. Khameneh ◽  
M. H. Hosseini ◽  
M. M. Moharreri
Keyword(s):  
Heavy Metal ◽  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Metal Ion ◽  
Kinetic Studies ◽  
Heavy Metal Ion ◽  
Ambient Conditions ◽  
X Ray ◽  
Metal Ion Adsorption ◽  
Map Analysis

Abstract The new clay modified with triazole and triazolium ligands was prepared in this research. These materials were applied as abundant and eco-friendly adsorbents for removal of heavy metal ions such as Pb(II), Co(II) and Zn(II) ions. The adsorption efficiency of these materials was calculated by relevant equations such as Langmuir and Freundlich as well as kinetic studies with pseudo-first-order and pseudo-second-order models. These adsorbents proved to be very active on heavy metal ion adsorption. The characterization of these new materials was carried out by various techniques such as X-ray diffraction, thermogravimetric analysis, scanning electron microscope (SEM), X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy as well as SEM-map analysis. Eventually, the catalytic activity of the adsorbents which treated with heavy metal ion solutions was studied in the reduction of nitroarenes to its corresponding amines. The prepared adsorbent–catalyst materials indicated efficient catalytic activity in the reduction of nitroarenes to amines in ambient conditions. Graphic abstract

scholarly journals Arabidopsis thaliana β1,2-xylosyltransferase: an unusual glycosyltransferase with the potential to act at multiple stages of the plant N-glycosylation pathway

2005 ◽  
Vol 388 (2) ◽  
pp. 515-525 ◽  
Author(s):  
Peter BENCÚR ◽  
Herta STEINKELLNER ◽  
Barbara SVOBODA ◽  
Jan MUCHA ◽  
Richard STRASSER ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Substrate Specificity ◽  
Metal Ion ◽  
Catalytic Domain ◽  
Protein Characterization ◽  
Reaction Products ◽  
Glycosylation Sites ◽  
Glycosylation Pathway ◽  
Multiple Stages

XylT (β1,2-xylosyltransferase) is a unique Golgi-bound glycosyltransferase that is involved in the biosynthesis of glycoprotein-bound N-glycans in plants. To delineate the catalytic domain of XylT, a series of N-terminal deletion mutants was heterologously expressed in insect cells. Whereas the first 54 residues could be deleted without affecting the catalytic activity of the enzyme, removal of an additional five amino acids led to the formation of an inactive protein. Characterization of the N-glycosylation status of recombinant XylT revealed that all three potential N-glycosylation sites of the protein are occupied by N-linked oligosaccharides. However, an unglycosylated version of the enzyme displayed substantial catalytic activity, demonstrating that N-glycosylation is not essential for proper folding of XylT. In contrast with most other glycosyltransferases, XylT is enzymatically active in the absence of added metal ions. This feature is not due to any metal ion directly associated with the enzyme. The precise acceptor substrate specificity of XylT was assessed with several physiologically relevant compounds and the xylosylated reaction products were subsequently tested as substrates of other Golgi-resident glycosyltransferases. These experiments revealed that the substrate specificity of XylT permits the enzyme to act at multiple stages of the plant N-glycosylation pathway.

Assembly of transition metal ion on cellulose surface anchored with azo-Schiff base and its catalytic activity for H2O2 decomposition

2015 ◽  
Vol 57 (41) ◽  
pp. 19190-19198 ◽  
Author(s):  
Kai Zhang ◽  
Aiqin Gao ◽  
Chao Zhang ◽  
Kongliang Xie
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Transition Metal ◽  
Metal Ion ◽  
Transition Metal Ion ◽  
H2o2 Decomposition ◽  
Cellulose Surface

scholarly journals Porphyrin in prebiotic catalysis: Ascertaining a route for the emergence of early metalloporphyrins

2021 ◽  
Author(s):  
Shikha Dagar ◽  
Susovan Sarkar ◽  
Sudha Rajamani
Keyword(s):  
Catalytic Activity ◽  
Molecular Evolution ◽  
Transition Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Selective Advantage ◽  
Metal Porphyrin ◽  
Catalytic Core ◽  
Prebiotic Catalysis ◽  
Mediated Oxidation

Metal ions are known to catalyze certain prebiotic reactions. However, the transition from metal ions to extant metalloenzymes remains unclear. Porphyrins are found ubiquitously in the catalytic core of many ancient metalloenzymes. In this study, we evaluated the influence of porphyrin-based organic scaffold, on the catalysis, emergence and putative molecular evolution of prebiotic metalloporphyrins. We studied the effect of porphyrins on the transition metal ion-mediated oxidation of hydroquinone (HQ). We report a change in the catalytic activity of the metal ions in the presence of porphyrin. This was observed to be facilitated by the coordination between metal ions and porphyrins or by formation of non-coordinated complexes. The metal-porphyrin complexes also oxidized NADH, underscoring its versatility at oxidizing more than one substrate. Our study highlights the selective advantage that some of the metal ions would have had in the presence of porphyrin, underscoring their role in shaping the evolution of protometalloenzymes.

scholarly journals Study on Nanofibrous Catalysts Prepared by Electrospinning for Methane Partial Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 479 ◽  
Author(s):  
Yuyao Ma ◽  
Yuxia Ma ◽  
Min Liu ◽  
Yang Chen ◽  
Xun Hu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Partial Oxidation ◽  
Metal Ion ◽  
Gas Flow ◽  
Catalytic Performance ◽  
Methane Partial Oxidation ◽  
Particle Sizes ◽  
Ion Content ◽  
High Reduction ◽  
Al2o3 Catalyst

Electrospinning is a simple and efficient technique for fabricating fibrous catalysts. The effects of preparation parameters on catalyst performance were investigated on fibrous Ni/Al2O3 catalysts. The catalyst prepared with H2O/C2H5OH solvent showed higher catalytic activity than that with DMF/C2H5OH solvent because of the presence of NiO in the catalyst prepared with DMF/C2H5OH solvent. The metal ion content of the precursor also influences catalyst properties. In this work, the Ni/Al2O3 catalyst prepared with a solution containing the metal ion content of 30 wt % demonstrated the highest Ni dispersion and therefore the highest catalytic performance. Additionally, the Ni dispersion decreased as calcination temperature was enhanced from 700 to 900 °C due to the increased Ni particle sizes, which also caused a high reduction temperature and low catalytic activity in methane partial oxidation. Finally, the fibrous Ni/Al2O3 catalysts can achieve high syngas yields at high reaction temperatures and high gas flow rates.

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