• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.30-36
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• 1988

The effect of high pressure on the stability of copper(II), cadmium(II) and zinc (II) complex ions with ethylenediamine, propylenediamine, diethylenetriamine has been investigated polarographically. 0.10M KN$O_3$ solution was used as a supporting electrolyte. The concentration of chelating agents was varied from 0.01M to 1.00M. The dissociation constants of metal complex ions were increased with increasing the pressure from 1 atmosphere to 1,500 atmospheres. The increment of the dissociation constant per unit atmosphere varied from 1.1 ${\times} 10^{-3}$% for Cu(dien)$_2^{2+}$ to 5.0 ${\times} 10^{-3}$ % for Zn(en)$_2^{2+}$.

• Journal of Life Science
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• v.6 no.4
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• pp.241-249
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• 1996

A collagenase was isolated from the culture filtrate of Vibrio mimicus (ATCC 33658). The enzyme was purified to homogeneity by ammonium sulfate precipitation and DEAE-Sephadex A-50 chromatography, which an activity recovery of 22%. The molecular weight of the purified enzyme was estimated to be 42 kDa by SDS-polyacrylamide gel electrophoresis and gel filtration, indication a monomer structure. The optimum pH and temperature od the enzyme for insoluble collagen (Type I) were around 7.75 and 28$\circ$C, respectively. Some chelating agents and serine protease inhibitor inactivated the enzyme, but L-cysteine and histidine did not affect the activity. The amino acid composition indicated that the collagenase contained high amounts of amino acid residues of glycine and alanine. The K$_{m}$ and R$_{cat}$/K$_{m}$ values for the collagenase, using insoluble collagen (type I) as substrate, were 2.86 mg/ml and 972.28 U/mg-protein, respectively.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1580-1581
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• 2008

We investigated the effects of intermittent hydrostatic pressure with various duration of resting period on changes in calcium ($Ca^{2+}$) concentration and adhesive forces of cells on substrates. The quantitive adhesive forces of cells were measured under various resting periods. When the pressure applied to the cells, the concentration of $Ca^{2+}$ increased. Under intermittent hydrostatic pressure, the concentration of $Ca^{2+}$ was maintained under a resting period of 15 min, while it was not decreased with other resting periods of less than 15 min. With a resting period of 15 min, the magnitudes of adhesive forces were significantly increase. In addition, the adhesive forces were measured with and without $Ca^{2+}$ chelating agents to evaluate the effect of $Ca^{2+}$ on cell adhesiveness. When $Ca^{2+}$ ions were chelated, the adhesive forces dramatically decreased, even under intermittent hydrostatic pressure. We conclude that $Ca^{2+}$ plays an crucial role in modulating the adhesive forces of cells, and that the concentration of $Ca^{2+}$ can be increased by intermittent hydrostatic stimuli.

• Journal of Microbiology
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• v.43 no.3
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• pp.237-243
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• 2005

The protease purified from Bacillus cereus JH108 has the function of leucine specific endopeptidase. When measured by hydrolysis of synthetic substrate (N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide), the enzyme activity exhibited optimal activity at pH 9.0, $60^{\circ}C$. The endopeptidase activity was stimulated by $Ca^{++},\;Co^{++},\;Mn^{++},\;Mg^{++},\;and\;Ni^{++}$, and was inhibited by metal chelating agents such as EDTA, 1,10-phenanthroline, and EGTA. Addition of serine protease inhibitor, PMSF, resulted in the elimination of the activity. The endopeptidase activity was fully recovered from the inhibition of EDTA by the addition of 1 mM $Ca^{++}$, and was partially restored by $Co^{++}\;and\;Mn^{++}$, indicating that the enzyme was stabilized and activated by divalent cations and has a serine residue at the active site. Addition of $Ca^{++}$ increased the pH and heat stability of endopeptidase activity. These results show that endopeptidase requires calcium ions for activity and/or stability. A Lineweaver-Burk plot analysis indicated that the $K_m$ value of endopeptidase is 0.315 mM and $V_{max}$ is 0.222 ) is $0.222\;{\mu}mol$ of N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide per min. Bestatin was shown to act as a competitive inhibitor to the endopeptidase activity.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.3
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• pp.161-174
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• 1979

A review was made on the effect of organic matter application on the chemical characteristics of soils such as pH, solubilities of minerals, and cation exchange capacity mainly at flooded rice soils. The review can be summarized as follows: 1. Application of organic material such as rice straw and compost in flooded rice soil leads to a temporary lowering of soil pH at the earlier stage of soil reduction, due to the production of various organic acids and carbonic acid. This temporary lowered pH is replaced with the production of alkaline substances such as ammonia as the reduction of soil proceeds. 2. Incorporation of organic materials intensifies the ferrous iron, dissolving various minerals, virtually to the increase in electrical conductivity of soils. 3. Organic materials also play an important role in dissolving soil minerals through the production of various chelating agents. 4. Application of soil organic matter significantly increases cation exchange capacity of soils. 5. Continuous application of rice straw or compost leads to the increase in soil organic matter content to some extent, up to the level of equilibrium. In soils low in organic matter the equilibrium level is attained with five years continuous application of compost. 6. The manner of chemical fertilizer application influences the accumulation of organic matter applied in soils. Low levels of fertilization lowers the accumulation while high levels of fertilization accerelates the accumulation.

• Journal of Applied Biological Chemistry
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• v.43 no.3
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• pp.156-160
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• 2000

The possible mechanism of the DNA strand breaking activity of the hot-water extract of Fructus Chaenomelis (dried fruit of Chaenomeles sinensis) in a closed circular duplex replica form DNA (RFI DNA) was studied through agarose gel electrophresis under various conditions. Induction of DNA strand scission by the hot-water extract of C. sinensis occurred in dose and time-dependent manners. $Cu^{2+}$ was indispensable for the induction of DNA strand breakage. Exogeneous chelating agents inhibited the DNA breaking activity, conforming the catalytic action of $Cu^{2+}$ on generation of free radicals responsible for oxidative damage. Antioxidant enzymes and some radical scavengers were used to investigate the major radical species triggering the DNA strand scission, demonstrating that a highest inhibitory activity was found in the presence of catalase, while less in the presence of tiron (a scavenger for superoxide radical), 2-aminoethyl-isothiuroniumbromide-HBr, cysteamine (scavengers for hydroxyl radical), and 1,4-diazabicyclo [2,2,2] octane (a scavenger for singlet oxygen) in decreasing order. The findings implied that oxygen radical species generated in presence of transition divalent cation during the oxidation of some compounds contained in the hot-water extract of C. sinensis is mainly responsible for inducing genotoxicity.

• The Korean Journal of Zoology
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• v.36 no.4
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• pp.487-495
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• 1993

TRH (Thvrotropin-Releasing Hormone) known to regulate the transcription of the TSH (Thyroid-Stimulating Hormones gene in pituitary cells, but little is understood about the mechanism(sl involved. re present study was attempted to elucidate the role of Ca2+ movement through the voltage-gated channels in the regulation of TSH gene transcription. The c-fos is one of immediate early genes and used as model system for the investigation of signaling pathwavs involved in various stimuli. The changes of c-fos mRNA levels were determined after treatment of various agents using Northern and slot hybridization analysis. The c-fos mRNA was rapidly and transiently induced by TRH (about 3-fold) in GH3 cells and this induction was repressed by calcium chelating agent (EGTA), calcium channel blocker (verapamil) anti protein kinase C inhibitor (aminoacridine). The abilities of forskolin (adenvlate cvclase activators, PMA (protein kinase C activator), and A23187 (calcium ionophore) to affect c-ios gene transcription, either alone or in combination with TRH were tested in the same cells. All of them significantly increased the level of c-fos mRUA. However, no additive relationship was observed in all combined treatments except forskolin. These results suggest that TRH action on the c-fos gene activation is mediated by calcium influx as well as through protein kinase C.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2381-2386
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• 2013

A new series of Mn(II) and Mo(VI) complexes containing the Schiff bases hydrazinecarbothioamide and hydrazinecarboxamide of 5,6-dimethyl-1H-indol-2,3-dione have been synthesized. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, molecular weight determinations and spectral studies viz. electronic IR, ESR, $^1H$ NMR and $^{13}C$ NMR and X-ray diffraction spectral studies. The magnetic moment values of the manganese(II) complexes are in the range of 5.80-6.15 B.M. suggesting a high spin state of manganese in these complexes. The spectral data are consistent with a tetrahedral geometry around Mn(II) and an octahedral geometry for Mo(VI), in which the ligands act as bidentate chelating agents, coordinated through the nitrogen and sulfur/oxygen atoms. The ligands and their metal complexes have been tested against a number of pathogenic fungi and bacteria at different concentrations and were found to possess sufficient fungicidal and bactericidal properties. Further, the complexes were also tested for their antifertility activity in male albino rats and the results were indeed positive.

• Toxicological Research
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• v.33 no.4
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• pp.299-304
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• 2017

Thallium and its compounds are a class of highly toxic chemicals that cause wide-ranging symptoms such as gastrointestinal disturbances; polyneuritis; encephalopathy; tachycardia; skin eruptions; hepatic, renal, cardiac, and neurological toxicities; and have mutagenic and genotoxic effects. The present research aimed to evaluate the efficacy of the chelating agents deferasirox (DFX) and deferiprone (L1) in reducing serum and tissue thallium levels after the administration of thallium (III), according to two different dosing regimens, to several groups of Wistar rats for 60 days. It was hypothesized that the two chelators might be more efficient as a combined therapy than as monotherapies in removing thallium (III) from the rats' organs. The chelators were administered orally as either single or combined therapies for a period of 14 days. Serum and tissue thallium (III) and iron concentrations were determined by flame atomic absorption spectroscopy. Serum and tissue thallium (III) levels were significantly reduced by combined therapy with DFX and L1. Additionally, iron concentrations returned to normal levels and symptoms of toxicity decreased.

• Membrane and Water Treatment
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• v.10 no.3
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• pp.231-237
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• 2019

Peroxymonosulfate (PMS) in combination with Cu(II) was examined to inactivate E. coli and MS2 coliphage in natural water. The combined system (i.e., the Cu(II)/PMS system) caused a synergistic inactivation of E. coli and MS2, in contrast with either Cu(II) or PMS alone. Increasing the concentration of PMS enhanced the inactivation of E. coli and MS2, but after a certain point, it decreased the efficacy of the microbial inactivation. In the Cu(II)/PMS system, adding reactive oxidant scavengers marginally affected the E. coli inactivation, but the inhibitory effects of copper-chelating agents were significant. Fluorescent assays indicated that the Cu(II)/PMS system greatly increased the level of reactive oxidants inside the E. coli cells. The sequential addition of Cu(II) and PMS inactivated more E. coli than did adding the two simultaneously; in particular, the inactivation efficacy was much higher when Cu(II) was added first. The observations from the study collectively showed that the microbial inactivation by the Cu(II)/PMS system could be attributed to the toxicity of Cu(I) as well as the intracellular oxidative stress induced by Cu(III) or radical species.