Identification of the metal center of chlorothalonil hydrolytic dehalogenase and enhancement of catalytic efficiency by directed evolution

2016 ◽  
Vol 1 (1) ◽  
pp. 30 ◽  
Author(s):  
Honghong Chen ◽  
Hui Wang ◽  
Tongtong Wang ◽  
Songren Huang ◽  
Xiaoxia Zang ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Metal Ion ◽  
Divalent Cations ◽  
Catalytic Efficiency ◽  
Fold Increase ◽  
Atomic Emission ◽  
Luria Bertani ◽  
Metal Center ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission Spectrometry

Chlorothalonil hydrolytic dehalogenase (Chd) is one of two reported hydrolytic dehalogenases for halogenated aromatics, and its catalysis is independent of coenzyme A and ATP. Earlier studies have established that the catalytic activity of Chd requires zinc ions. In this study, the metal center of Chd was systematically investigated. The metal content of Chd was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES), and there were 2.14 equivalents of zinc/mol of protein, indicating that Chd contains a binuclear (Zn2+-Zn2+) center. It was found that other divalent cations, such as cobalt (Co2+) and cadmium (Cd2+), could substitute zinc (Zn2+) leading to relative activities of 91.6% and 120.0%, whereas manganese (Mn2+) and calcium (Ca2+) could substitute Zn2+ leading to relative activities of 29.1% and 57.0%, respectively. The enzymatic properties of these different metal ion-substituted Chd variants were also compared. Error-prone PCR and DNA shuffling methods were applied to directly evolve Chd to generate variants with higher catalytic efficiencies of chlorothalonil. Enhanced Chd variants were selected based on the formation of clear haloes on Luria-Bertani plates supplemented with chlorothalonil. One variant, Q146R/N168Y/S303G, exhibited a 4.43-fold increase in catalytic efficiency, showing the potential for application in the dehalogenation and detoxification of chlorothalonil contaminated-sites.

Effect of pH on Nanoparticle Structure in Radiochemical Synthesis of PtCu Alloy Supported on γ-Fe2O3 and Carbon

MRS Advances ◽  
2016 ◽  
Vol 1 (6) ◽  
pp. 427-432 ◽  
Author(s):  
Tomohisa Okazaki ◽  
Satoshi Seino ◽  
Junichiro Kugai ◽  
Yuji Ohkubo ◽  
Takashi Nakagawa ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Metal Ion ◽  
Precursor Solution ◽  
Atomic Emission ◽  
Lattice Parameter ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission Spectrometry ◽  
X Ray ◽  
Nanoparticle Structure ◽  
Ptcu Alloy

ABSTRACTPtCu nanoparticles were synthesized with different pH and support conditions using radiochemical process. The nanoparticle structures were characterized by transmission electron microscopy, inductively coupled plasma atomic emission spectrometry, X-ray absorption spectroscopy, and X-ray diffraction techniques. The nanoparticle structure was relevant to the pH of the precursor solutions. The lattice parameter of PtCu alloy increased in high pH samples, which indicates the critical effect of metal ion adsorption in precursor solution on nanoparticle structure.

Silicate analysis of carbonated rocks using ICP-AES with calibration by the concentration ratio

2020 ◽  
Vol 86 (5) ◽  
pp. 16-21
Author(s):  
T. A. Karimova ◽  
G. L. Buchbinder ◽  
S. V. Kachin
Keyword(s):  
Inductively Coupled Plasma ◽  
Concentration Ratio ◽  
Total Error ◽  
Atomic Emission ◽  
Emission Spectrometry ◽  
Calibration Error ◽  
Plasma Atomic Emission Spectrometry ◽  
Standard Samples ◽  
Inductively Coupled ◽  
Carbonate Materials

Calibration by the concentration ratio provides better metrological characteristics compared to other calibration modes when using the inductively coupled plasma atomic emission spectrometry (ICP-AES) for analysis of geological samples and technical materials on their base. The main reasons for the observed improvement are: i) elimination of the calibration error of measuring vessels and the error of weighing samples of the analyzed materials from the total error of the analysis; ii) high intensity of the lines of base element; and iii) higher accuracy of measuring the ratio of intensities compared to that of measuring the absolute intensities. Calcium oxide is better suited as a base when using calibration by the concentration ratio in analysis of carbonate rocks, technical materials, slags containing less than 20% SiO2 and more than 20% CaO. An equation is derived to calculate the content of components determined in carbonate materials when using calibration by the concentration ratio. A method of ICP-AES with calibration by the concentration ratio is developed for determination of CaO (in the range of contents 20 – 100%), SiO2 (2.0 – 35%), Al2O3 (0.1 – 30%), MgO (0.1 – 20%), Fe2O3 (0.5 – 40%), Na2O (0.1 – 15%), K2O (0.1 – 5%), P2O5 (0.001 – 2%), MnO (0.01 – 2%), TiO2 (0.01 – 2.0%) in various carbonate materials. Acid decomposition of the samples in closed vessels heated in a HotBlock 200 system is proposed. Correctness of the procedure is confirmed in analysis of standard samples of rocks. The developed procedure was used during the interlaboratory analysis of the standard sample of slag SH17 produced by ZAO ISO (Yekaterinburg, Russia).

scholarly journals Distribution and Mode of Occurrence of Co, Ni, Cu, Zn, As, Ag, Cd, Sb, Pb in the Feed Coal, Fly Ash, Slag, in the Topsoil and in the Roots of Trees and Undergrowth Downwind of Three Power Stations in Poland

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 133
Author(s):  
Henryk R. Parzentny ◽  
Leokadia Róg
Keyword(s):  
Inductively Coupled Plasma ◽  
Coal Fly Ash ◽  
Atomic Emission ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission Spectrometry ◽  
X Ray ◽  
Inductively Coupled ◽  
Power Stations ◽  
Mode Of Occurrence ◽  
Feed Coal

It is supposed that the determination of the content and the mode of occurrence of ecotoxic elements (EE) in feed coal play the most significant role in forecasting distribution of EE in the soil and plants in the vicinity of power stations. Hence, the aim of the work was to analyze the properties of the feed coal, the combustion residues, and the topsoil which are reached by EE together with dust from power stations. The mineral and organic phases, which are the main hosts of EE, were identified by microscopy, X-ray powder diffraction, inductively coupled plasma atomic emission spectrometry, and scanning electron microscope with an energy dispersive X-ray methods. The highest content of elements was observed in the Oi and Oe subhorizons of the topsoil. Their hosts are various types of microspheres and char, emitted by power stations. In the areas of long-term industrial activity, there are also sharp-edged grains of magnetite emitted in the past by zinc, lead, and ironworks. The enrichment of the topsoil with these elements resulted in the increase in the content of EE, by between 0.2 times for Co; and 41.0 times for Cd in the roots of Scots pine, common oak and undergrowth, especially in the rhizodermis and the primary cortex and, more seldom, in the axle roller and cortex cells.

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