• Korean Journal of Microbiology
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• v.21 no.3
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• pp.135-142
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• 1983

The presence of polyphosphate phosphohydrolase (PPPH) and tripolyphosphate phosphohydrolase (TPPH) in Chlorella ellipsoidea were confirmed from the cell-free extract of the algal cells and three forms of PPPH were isolated, purified, and measured Km-Vmax value and inhibitory effect by metal ions, respectively. PPPH was most active at pH7.2, whereas TPPH at pH 7.6. Both enzymes exhibited their maximum activity at $37^{\circ}C$. For the manifestation of catalytic activity, divalent, divalent metal ions are needed, and the best activator for both enzymes was $Co^{++}\;ions\;(10^{-3}M)$. These enzymes were inhibited by $Hg^{++}\;ions\;(10^{-3}M)$ considerably. PPPH from Chlorella ellipsoidea was purified by ammonium sulfate fractionation, ion-exchange chromatography on DEAE-Sephadex A-25, and gel filtration on Sephadex G-100, and some properties of the three different fraction with PPPH activity $(PPPH_1,\;PPPH_2,\;and\;PPPH_3)$ were found, i.e, PPPH has multiple form. The Km values of $PPPH_1,\;PPPH_2,\;and\;PPPH_3$ obstained were $6.25{\times}10^{-4}M,\;10^{-4}M-4/M,\;and\;3.33{times}10^{-4}M$ and Vmax were 3.33 mM/min, 3.33 mM/min, and 2.67 mM/min, respectively. It was shown that the types of inhibition of $Hg^{++} on the activities of three forms of PPPH were competitive inhibition.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.302-310
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• 2012

Bio assay of mercury and cadmium ions were searched using voltammetric analysis using DNA doped carbon nanotube paste electrodes (DCP). The square-wave stripping voltammetryic optimized results indicated working ranges of 1-10.0 $ngL^{-1}$ and 20-100 $ugL^{-1}$, Hg(II) Cd(II) within an accumulation time of 120 seconds, in 0.1-M phosphate buffer solutions of pH 6.3. The relative standard deviations of 5 $ngL^{-1}$ Hg(II) and Cd(II) that observed were 0.14 and 0.22% (n=12), respectively, using optimum conditions. The low detection limit (S/N) was pegged at 0.1 $ngL^{-1}$ ($4.9{\times}10^{-11}M$) Hg(II) and 0.2 $ngL^{-1}$ ($1.77{\times}10^{-10}M$) Cd(II). The developed methods can be applied to assays in biological fish kidneys and water samples.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3707-3710
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• 2010

A chromo/fluorogenic $NO_2S_2$-macrocycle L functionalized with nitrobenzofurazan unit as a dual-signaling probe was synthesized and structurally characterized by single crystal X-ray analysis. In a cation-induced color change experiment, L exhibited excellent $Hg^{2+}$ ion selectivity by showing the color change from orange-red to yellow. However, this hypochromic shift by $Hg^{2+}$ was observed for the weaker coordinating anion system such as ${NO_3}^-$ and ${ClO_4}^-$ ions. The observed anion effect is due to the strong coordination of anions inhibits the bond formation between $Hg^{2+}$ and the macrocyclic tert-N atom, which is sensitive to induce the color change. In the fluorometric experiment, L showed chelate-enhanced fluorescence change effect only with $Hg^{2+}$ ion, together with a change from yellow to green emission. The sensing ability for $Hg^{2+}$ with the proposed chemosensor L is due to the stable complexation with 1:1 stoichiometry (metal-to-ligand).

• Journal of Microbiology and Biotechnology
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• v.20 no.5
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• pp.917-924
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• 2010

The practicability of transgenic tobacco engineered to express bacterial native mercuric reductase (MerA), responsible for the transport of $Hg^{2+}$ ions into the cell and their reduction to elemental mercury ($Hg^0$), without any codon modification, for phytoremediation of mercury pollution was evaluated. Transgenic tobacco plants reduce mercury ions to the metallic form; take up metallic mercury through their roots; and evolve the less toxic elemental mercury. Transformed tobacco produced a large amount of merA protein in leaves and showed a relatively higher resistance phenotype to $HgCl_2$ than wild type. Results suggest that the integrated merA gene, encoding mercuric reductase, a key enzyme of the bacterial mer operon, was stably integrated into the tobacco genome and translated to active MerA, which catalyzes the bioconversion of toxic $Hg^{2+}$ to the least toxic elemental $Hg^0$, and suggest that MerA is capable of reducing the $Hg^{2+}$, probably via NADPH as an electron donor. The transgenic tobacco expressing merA volatilized significantly more mercury than wild-type plants. This is first time we are reporting the expression of a bacterial native merA gene via the nuclear genome of Nicotiana tabacum, and enhanced mercury volatilization from tobacco transgenics. The study clearly indicates that transgenic tobacco plants are reasonable candidates for the remediation of mercurycontaminated areas.

• Journal of Environmental Science International
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• v.2 no.1
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• pp.61-72
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• 1993

Result of this study indicate that two criteria must be met in order to have effective macrocycle-mediated transport in these emulsionsystem. First, one must effective extraction of the post transition metals, $Cd^{2+}$. $Pb^{2+}$ and $Hg^{2+}$ , into toluene membrane. The effectiveness of this extraction is greatest if log K values for the metal-macrocycle interaction is large. Second, the ratio of the log K values for the metal ion-receiving phase to the metal ion-macrocycle interaction must be large enough to ensure quantitative stripping of the metal ion at the toluene phase interface. Control of the first step can be obtained by appropriate selection of macrocycle donor atom, substituents, and cavity radius. The second step can be controlled by selecting the proper complexing agent for inclusion in the receiving phase. The order of the transport, when using the several $A^-$ species such as $SCN^-$, $1^-$, $Br^-$ and $Cl^-$ is the order of the changing degree of solvation for $A^-$ and the transport of the metals is also affected by the control of concentration for receiving species because of solubility-differences. In this study, we can seperate each single metal ion from the mixture of $Cd^{2+}$, $Pb^{2+}$, and $Hg^{2+}$ ions by using the toluene membranes controlled by optimized conditions. Transport of the single metal is also very good, and alkaline and alkaline earth metals as interferences ions did not affect the seperation of the metals in this macrocycle-liquid membrances but transition metal ions were partially affected as interferences for the post transition metal ions.

• Bulletin of the Korean Chemical Society
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• v.21 no.10
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• pp.1011-1014
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• 2000

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.2031-2035
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• 2010

A triple-probe channel type chemosensor based on an $NO_2S_2$-macrocycle functionalized with phenyltricyanovinyl group was synthesized and its sensing characteristics were examined. The pink-red solution of L changed selectively to pale yellow upon addition of $Hg^{2+}$. The selective fluorometric response of L to all the tested metal ions was studied. The results showed that a large enhancement of the fluorescence of L was observed only in the case of $Hg^{2+}$. In addition, L showed large anodic shift (~ 0.3 V) for the addition of excess $Hg^{2+}$. Through above three observed results by the different techniques, we confirmed that the proposed chemosensor acts as the multiple-probe channel sensing material. The crystal structure of mercury(II) nitrate complexs of L which shows a 1-D polymer network with a formula $[Hg_2(L)_2(NO_3)_2({\mu}-NO_3)_2]_n$ was also reported.

• Bulletin of the Korean Chemical Society
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• v.28 no.1
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• pp.68-72
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• 2007

A new PVC membrane potentiometric sensor that is highly selective to Hg2+ ions was prepared, using bis(2-hydroxybenzophenone) butane-2,3-dihydrazone (HBBD) as an excellent hexadendates neutral carrier. The sensor works satisfactorily in the concentration range of 1.0 × 10-6 to 1.0 × 10-1 mol L-1 (detection limit 4 × 10-7 mol L-1) with a Nernstian slope of 29.7 mV per decade. This electrode showed a fast response time (~8 s) and was used for at least 12 weeks without any divergence. The sensor exhibits good Hg2+ selectivity for a broad range of common alkali, alkaline earth, transition and heavy metal ions (lithium, sodium, potassium, magnesium, calcium, copper, nickel, cobalt, zinc, cadmium, lead and lanthanum). The electrode response is pH independent in the range of 1.5-4.0. Furthermore, the developed sensor was successfully used as an indicator electrode in the potentiometric titration of mercury ions with potassium iodide and the direct determination of mercury in some binary and ternary mixtures.

• Toxicological Research
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• v.24 no.1
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• pp.23-28
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• 2008

Voltammetric analysis of mercury ions was developed using paste electrodes (PEs) with DNA and carbon nanotube mixed electrodes. The optimized analytical results of the cyclic voltammetry (CV) of the $1{\sim}14ng\;L^{-1}Hg(II)$ concentration and the square wave (SW) stripping voltammetry of the $1{\sim}12ng\;L^{-1}Hg(II)$ working range within an accumulation time of 400 seconds were obtained in 0.1 M $NH_4H_2PO_4$ electrolyte solutions of pH 4.0. For the relative standard deviations of the $1ng\;L^{-1}Hg(II)$, which were observed at 0.078% (n = 15) at the optimum conditions, the low detection limit (S/N) was pegged at $0.2ng\;L^{-1}(7.37{\times}10^{-13}M)$ for Hg(II). The results can be applied to assays in biological fish kidneys and wastewater samples.

• Textile Coloration and Finishing
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• v.15 no.3
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• pp.146-153
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• 2003

This article describes the metal ions adsorption of chitosan fibers. The chitosan fibers were manufactured by wet spinning using 2% acetic acid as solvent, 10% aqueous sodium hydroxide as non solvent, and 4%chitosan solution as a solvent. The adsorption characteristics of chitosan fibers towards 100ppm solutions of various metal ions such as Cu(II), Cd(II), Cr(III), Hg(II) were examined at different pH value by ICP-Atomic Emission Spectrometer. The adhesiveness of metallic ions to the chitosan fiber were increased with the increase of pH and the decrease of denier. On the other hand, from pH4, chitosan fiber that is immersed in metal ion aqueous solution of Cu(II) and Cd(II) became homogeneous solution because is dissolved. The adhesiveness of metallic ions to chitosan fiber were found to increased in a sequence of Hg(II)> Cr(III)> Cu(II)> Cd(II). The antimicrobial characteristics of the chitosan fiber by adhered metal ions, virgin chitosan fiber, and cotton fiber were evaluated. The antimicrobial activity of the fibers were increased with the decrease of denier.