scholarly journals Affinity Immobilization of a Bacterial Prolidase onto Metal-Ion-Chelated Magnetic Nanoparticles for the Hydrolysis of Organophosphorus Compounds

2019 ◽  
Vol 20 (15) ◽  
pp. 3625 ◽  
Author(s):  
Wang ◽  
Lo ◽  
Chi ◽  
Lai ◽  
Lin ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Metal Ion ◽  
Organophosphorus Compounds ◽  
Storage Period ◽  
Immobilized Enzymes ◽  
Initial Activity ◽  
Transmission Electron ◽  
Nitrophenyl Phosphate ◽  
Affinity Immobilization ◽  
Hydrolysis Of

In this study, silica-coated magnetic nanoparticles (SiMNPs) with isocyanatopropyltriethoxysilane as a metal-chelating ligand were prepared for the immobilization of His6-tagged Escherichia coli prolidase (His6-EcPepQ). Under one-hour coupling, the enzyme-loading capacity for the Ni2+-functionalized SiMNPs (NiNTASiMNPs) was 1.5 mg/mg support, corresponding to about 58.6% recovery of the initial activity. Native and enzyme-bound NiNTASiMNPs were subsequently characterized by transmission electron microscopy (TEM), superparamagnetic analysis, X-ray diffraction, and Fourier transform infrared (FTIR) spectroscopy. As compared to free enzyme, His6-EcPepQ@NiNTASiMNPs had significantly higher activity at 70 °C and pH ranges of 5.5 to 10, and exhibited a greater stability during a storage period of 60 days and could be recycled 20 times with approximately 80% retention of the initial activity. The immobilized enzyme was further applied in the hydrolysis of two different organophosphorus compounds, dimethyl p-nitrophenyl phosphate (methyl paraoxon) and diethyl p-nitrophenyl phosphate (ethyl paraoxon). The experimental results showed that methyl paraoxon was a preferred substrate for His6-EcPepQ and the kinetic behavior of free and immobilized enzymes towards this substance was obviously different. Taken together, the immobilization strategy surely provides an efficient means to deposit active enzymes onto NiNTASiMNPs for His6-EcPepQ-mediated biocatalysis.

Metal ion catalyzed hydrolysis of ethyl p-nitrophenyl phosphate

2003 ◽  
Vol 93 (1-2) ◽  
pp. 61-65 ◽  
Author(s):  
J. Rawlings ◽  
W.W. Cleland ◽  
A.C. Hengge
Keyword(s):  
Metal Ion ◽  
Nitrophenyl Phosphate ◽  
Hydrolysis Of

scholarly journals Applications of Coordination Chemistry in Biological Systems

2014 ◽  
Vol 70 (a1) ◽  
pp. C1376-C1376
Author(s):  
Gurpreet Kaur ◽  
Richard Hartshorn
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Binding Sites ◽  
Metal Ion ◽  
Hydrolytic Enzymes ◽  
Dinuclear Complexes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nitrophenyl Phosphate ◽  
Hydrolysis Of

A novel 2,2′:6′,2″-terpyridine–picolylamine-based bridging ligand has been synthesized and fully characterized using a variety of analysis techniques including single crystal X-ray diffraction. As shown in figure (a), the ligand has both tridentate and bidentate metal binding sites available to coordinate with various metal ions. By varying the size of anions both dinuclear complexes and supramolecular assemblies have been produced. Addition of metal salts containing small anions like halides result in formation of Cu2L and Zn2L dinuclear complexes, figure (b), where one metal ion binds at each of the binding sites of the ligand. The metal ions in these complexes mimic active site of the hydrolytic enzymes and promote phosphatediester hydrolysis of model DNA/RNA compounds. Nearly ten times increase in the rate of hydrolysis of bis(p-nitrophenyl)phosphate (BNPP) is observed in comparison to the parent terpyridine and picolylamine complexes under physiological conditions. Larger anions like PF6-, ClO4-, SO42- , NO3- result in formation of Zn4L4 type squares via. head-to-head and tail-to-tail, HH-TT, (H=tridentate site, T=bidentate site) coordination of the ligand. The octahedrally bound Zn(II) ion between two tridentate sites can be replaced with Fe(II) to prepare Fe2Zn2L4 squares. A flat molecule of terephthalic acid was also deliberately encapsulated in the middle of the Fe2Zn2L4 square as shown in figure (c). The head-to-tail, HT, coordination of the ligand in case of Ni(II) results in formation of decanickel wheels, like [Ni10L10Cl4(H2O)6](Cl)15Br·~140H2O shown in figure (d). Due to the large structure of the molecule X-ray crystallographic studies rather have been quite challenging.

scholarly journals Renal sodium-potassium adenosine triphosphatase. Optical localization and x-ray microanalysis.

1975 ◽  
Vol 23 (11) ◽  
pp. 828-839 ◽  
Author(s):  
R Beeuwkes ◽  
S Rosen
Keyword(s):  
Atpase Activity ◽  
Electron Probe ◽  
Sequential Analysis ◽  
Relative Sensitivity ◽  
Initial Reaction ◽  
Initial Product ◽  
Sodium Potassium ◽  
Nitrophenyl Phosphate ◽  
Hydrolysis Of ◽  
Convoluted Tubules

The distribution of sodium-potassium adenosine triposphatase (Na-K-ATPase) activity in kidney sections has been studied by a method based on the hydrolysis of p-nitrophenyl phosphate in alkaline medium containing dimethyl sulfoxide. The products at each stage in the reaction sequence have been subjected to electron probe microanalysis. The initial product was identified as a mixture of KMgPO4 and Mg(PO4)2, and sequential analysis demonstrated the linearity of conversion of this product to a visible form. In human, rabbit and rat kidneys the distribution of activity was found to be essentially identical, with highest levels located in thick ascending limbs and distal convoluted tubules. The initial reaction was completely potassium dependent and was inhibited by ouabain in concentrations reflecting the relative sensitivity of microsomal Na-K-ATPase in each species. Measurement of initial product phosphorus by means of the electron probe is presented as a practical technique for direct quantitation of Na-K-ATPase activity in identified tubule segments.

scholarly journals Simultaneous Hydrolysis and Detection of Organophosphate by Benzimidazole Containing Ligand-Based Zinc(II) Complexes

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 714
Author(s):  
Gaber A. M. Mersal ◽  
Hamdy S. El-Sheshtawy ◽  
Mohammed A. Amin ◽  
Nasser Y. Mostafa ◽  
Amine Mezni ◽  
...  
Keyword(s):  
Square Wave Voltammetry ◽  
Limit Of Detection ◽  
Organophosphorus Compounds ◽  
Organophosphorus Pesticides ◽  
Carbon Paste ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Carbon Past Electrode ◽  
Hydrolysis Of ◽  
Biomimetic Sensor

The agricultural use of organophosphorus pesticides is a widespread practice with significant advantages in crop health and product yield. An undesirable consequence is the contamination of soil and groundwater by these neurotoxins resulting from over application and run-off. Here, we design and synthesize the mononuclear zinc(II) complexes, namely, [Zn(AMB)2Cl](ClO4) 1 and [Zn(AMB)2(OH)](ClO4) 2 (AMB = 2-aminomethylbenzimidazole), as artificial catalysts inspired by phosphotriesterase (PTE) for the hydrolysis of organophosphorus compounds (OPs) and simultaneously detect the organophosphate pesticides such as fenitrothion and parathion. Spectral and DFT (B3LYP/Lanl2DZ) calculations revealed that complexes 1 and 2 have a square-pyramidal environment around zinc(II) centers with coordination chromophores of ZnN4Cl and ZnN4O, respectively. Both 1 and 2 were used as a modifier in the construction of a biomimetic sensor for the determination of toxic OPs, fenitrothion and parathion, in phosphate buffer by square wave voltammetry. The hydrolysis of OPs using 1 or 2 generates p-nitrophenol, which is subsequently oxidized at the surface of the modified carbon past electrode. The catalytic activity of 2 was higher than 1, which is attributed to the higher electronegativity of the former. The oxidation peak potentials of p-nitrophenol were obtained at +0.97 V (vs. Ag/AgCl) using cyclic voltammetry (CV) and +0.88 V (vs. Ag/AgCl) using square wave voltammetry. Several parameters were investigated to evaluate the performance of the biomimetic sensor obtained after the incorporation of zinc(II) complex 1 and 2 on a carbon paste electrode (CPE). The calibration curve showed a linear response ranging between 1.0 μM (0.29 ppm) and 5.5 μM (1.6 ppm) for fenitrothion and 1.0 μM (0.28 ppm) and 0.1 μM (0.028 ppm) for parathion with a limit of detection (LOD) of 0.08 μM (0.022 ppm) and 0.51 μM (0.149 ppm) for fenitrothion and parathion, respectively. The obtained results clearly demonstrated that the CPE modified by 1 and 2 has a remarkable electrocatalytic activity towards the hydrolysis of OPs under optimal conditions.

scholarly journals A New Nanocomposite Packaging Based on LASiS-Generated AgNPs for the Preservation of Apple Juice

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 760
Author(s):  
Maria Chiara Sportelli ◽  
Antonio Ancona ◽  
Annalisa Volpe ◽  
Caterina Gaudiuso ◽  
Valentina Lavicita ◽  
...  
Keyword(s):  
Metal Ion ◽  
Chemical Characterization ◽  
Average Diameter ◽  
Biological Action ◽  
Metal Species ◽  
Ion Release ◽  
Bioactive Materials ◽  
Transmission Electron ◽  
Metal Ion Release ◽  
Bulk Chemical

Designing bioactive materials, with controlled metal ion release, exerting a significant biological action and associated to low toxicity for humans, is nowadays one of the most important challenges for our community. The most looked-for nanoantimicrobials are capable of releasing metal species with defined kinetic profiles, either by slowing down or inhibiting bacterial growth and pathogenic microorganism diffusion. In this study, laser ablation synthesis in solution (LASiS) has been used to produce bioactive Ag-based nanocolloids, in isopropyl alcohol, which can be used as water-insoluble nano-reservoirs in composite materials like poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Infrared spectroscopy was used to evaluate the chemical state of pristine polymer and final composite material, thus providing useful information about synthesis processes, as well as storage and processing conditions. Transmission electron microscopy was exploited to study the morphology of nano-colloids, along with UV-Vis for bulk chemical characterization, highlighting the presence of spheroidal particles with average diameter around 12 nm. Electro-thermal atomic absorption spectroscopy was used to investigate metal ion release from Ag-modified products, showing a maximum release around 60 ppb, which ensures an efficient antimicrobial activity, being much lower than what recommended by health institutions. Analytical spectroscopy results were matched with bioactivity tests carried out on target microorganisms of food spoilage.

Metal Ion Catalysis in the Hydrolysis of Potassium Ethyl Oxalate

Nature ◽  
1964 ◽  
Vol 204 (4964) ◽  
pp. 1189-1190
Author(s):  
ROBERT W. HAY ◽  
NEIL J. WALKER
Keyword(s):  
Metal Ion ◽  
Metal Ion Catalysis ◽  
Hydrolysis Of

scholarly journals Metal Ion Implanted Compliant Electrodes in Dielectric Electroactive Polymer (EAP) Membranes

2008 ◽  
Vol 61 ◽  
pp. 18-25 ◽  
Author(s):  
Philippe Dubois ◽  
Samuel Rosset ◽  
Muhamed Niklaus ◽  
Massoud Dadras ◽  
Herbert Shea
Keyword(s):  
Metal Ion ◽  
High Efficiency ◽  
Relative Displacement ◽  
Electroactive Polymer ◽  
Metallic Films ◽  
Key Factors ◽  
Nano Composite ◽  
Transmission Electron ◽  
Macro Scale ◽  
Compliant Electrodes

One of the key factors to obtain large displacements and high efficiency with dielectric electroactive polymer (DEAPs) actuators is to have compliant electrodes. Attempts to scale DEAPs down to the mm or micrometer range have encountered major difficulties, mostly due to the challenge of micropatterning sufficiently compliant electrodes. Simply evaporating or sputtering thin metallic films on elastomer membranes produces DEAPs whose stiffness is dominated by the metallic film. Low energy metal ion implantation for fabricating compliant electrodes in DEAPs presents several advantages: a) it is clean to work with, b) it does not add thick passive layers, and c) it can be easily patterned. We use this technology to fabricate DEAPs micro-actuators whose relative displacement is the same as for macro-scale DEAPs. With transmission electron microscope (TEM) we observed the formation of metallic clusters within the elastomer (PDMS) matrix, forming a nano-composite. We focus our studies on relating the properties of this nano-composite to the implantation parameters. We identified the optimal implantation parameters for which an implanted electrode presents an exceptional combination of high electrical conductivity and low compliance.

Direct-Writing of Cu Nano-Patterns with an Electron Beam

2015 ◽  
Vol 21 (6) ◽  
pp. 1639-1643 ◽  
Author(s):  
Shih-En Lai ◽  
Ying-Jhan Hong ◽  
Yu-Ting Chen ◽  
Yu-Ting Kang ◽  
Pin Chang ◽  
...  
Keyword(s):  
Electron Beam ◽  
Exposure Time ◽  
Metal Ion ◽  
Reduction Rate ◽  
Industrial Applications ◽  
Growth Stages ◽  
Sample Holder ◽  
Direct Writing ◽  
Transmission Electron ◽  
Aqueous Layer

AbstractWe demonstrate direct electron beam writing of a nano-scale Cu pattern on a surface with a thin aqueous layer of CuSO4 solution. Electron beams are highly maneuverable down to nano-scales. Aqueous solutions facilitate a plentiful metal ion supply for practical industrial applications, which may require continued reliable writing of sophisticated patterns. A thin aqueous layer on a surface helps to confine the writing on the surface. For this demonstration, liquid sample holder (K-kit) for transmission electron microscope (TEM) was employed to form a sealed space in a TEM. The aqueous CuSO4 solution inside the sample holder was allowed to partially dry until a uniform thin layer was left on the surface. The electron beam thus reduced Cu ions in the solution to form the desired patterns. Furthermore, the influence of e-beam exposure time and CuSO4(aq) concentration on the Cu reduction was studied in this work. Two growth stages of Cu were shown in the plot of Cu thickness versus e-beam exposure time. The measured Cu reduction rate was found to be proportional to the CuSO4(aq) concentration.

Sign in / Sign up

Export Citation Format

Share Document