• Journal of the Korean institute of surface engineering
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• v.44 no.3
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• pp.117-123
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• 2011

We investigated the spectroscopic and electrochemical properties of the citrate-based CuNi solution at different solution pH and analyzed various surface properties of CuNi codeposition layer. By combining UV-Visible spectroscopic data with potentiodynamic polarization curves, it could be found that the complexation of $Ni^{2+}$-citrate pair was completed at lower solution pH than $Cu^{2+}$-citrate pair and was affected by the coexistent $Cu^{2+}$ ions, while the complexation between $Cu^{2+}$ ions and citrate was not sensitive to the presence of $Ni^{2+}$ ions. Also, the electron transfer from cathode to $Cu^{2+}$-citrate and$Ni^{2+}$-citrate was hindered by strong complexation between $Cu^{2+}/Ni^{2+}$ ions and citrate and so apparent codeposition current densities were reduced as the solution pH increases. CuNi codeposited layers had a higher Cu content when they were prepared at high pH solution due to the suppression of Ni deposition, and when codeposition was executed in an agitated condition due to the acceleration of mass transfer of $Cu^{2+}$ ions in the solution. Actually, solution pH had little effect on the surface morphology and deposits orientation, but greatly influenced the corrosion resistance in 3.5% NaCl solution by modifying the chemical composition of CuNi layers and so pH 3 was expected as the most suitable solution pH in the viewpoint of corrosion coatings.

• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.18-21
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• 1996

A continuous production of fructooligosaccharides from sucrose was investigated by fructosyltransferase immobilized on a high porous resin, Diaion HPA25. The optimum pH(5.5) and temperature(55$^{\circ}C$) of the enzyme for activity was unaltered by immobilization, and the immobilized enzyme became less sensitive to the pH change. The optimal operation conditions of the immobilized enzyme column for maximizing the productivity were as follows: 600g/L of sucrose feed concentration, flow rate of superficial space velocity 2.7h-1. When the enzyme column was run at 50$^{\circ}C$, about 8% loss of the initial activity of immobilized enzyme was observed after 30 days of continuous operation, during which high productivity of 1174g/L$.$h was achieved. The kinds of products obtained using the immobilized enzyme were almost the same as those using soluble enzymes or free cells.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.2
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• pp.241-249
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• 2017

Plasma membrane hyperpolarization associated with activation of $Ca^{2+}$-activated $K^+$ channels plays an important role in sperm capacitation during fertilization. Although Slo3 (slowpoke homologue 3), together with the auxiliary ${\gamma}^2$-subunit, LRRC52 (leucine-rich-repeat-containing 52), is known to mediate the pH-sensitive, sperm-specific $K^+$ current KSper in mice, the molecular identity of this channel in human sperm remains controversial. In this study, we tested the classical $BK_{Ca}$ activators, NS1619 and LDD175, on human Slo3, heterologously expressed in HEK293 cells together with its functional interacting ${\gamma}^2$ subunit, hLRRC52. As previously reported, Slo3 $K^+$ current was unaffected by iberiotoxin or 4-aminopyridine, but was inhibited by ~50% by 20 mM TEA. Extracellular alkalinization potentiated hSlo3 $K^+$ current, and internal alkalinization and $Ca^{2+}$ elevation induced a leftward shift its activation voltage. NS1619, which acts intracellularly to modulate hSlo1 gating, attenuated hSlo3 $K^+$ currents, whereas LDD175 increased this current and induced membrane potential hyperpolarization. LDD175-induced potentiation was not associated with a change in the half-activation voltage at different intracellular pHs (pH 7.3 and pH 8.0) in the absence of intracellular $Ca^{2+}$. In contrast, elevation of intracellular $Ca^{2+}$ dramatically enhanced the LDD175-induced leftward shift in the half-activation potential of hSlo3. Therefore, the mechanism of action does not involve pH-dependent modulation of hSlo3 gating; instead, LDD175 may modulate $Ca^{2+}$-dependent activation of hSlo3. Thus, LDD175 potentially activates native KSper and may induce membrane hyperpolarization-associated hyperactivation in human sperm.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.241-246
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• 2002

A gene coding for endo-$\beta$-1,3-1,4-glucanase of Bacillus circulans was subcloned into Escherichia coli Ml5 using pQE30 as an expression vector. Endo-$\beta$-1,3-1,4-glucanase produced by the recombinant expression plas-mid pLQ43 was intactly purified to a single protein through a nickel-nitrilotriacetic acid (Ni-NTA) metal-affinity chromatography method. The molecular mass of the purified enzyme was estimated to be 28 kDa by SDS-PAGE. The optimum pH and temperature of the enzyme activity were pH 6.8 and $60^{\circ}C$, respectively. This enzyme was fairly stable in the pH ranging 5.5~7.5 and at the temperatures lower than $55^{\circ}C$. The enzyme appeared to be sensitive to most of the metal ions, especially to $Hg^{2＋$, and also to methanol, ethanol, isopropanol or 1-butanol at a concentration of 10%(v/v).

• Bulletin of the Korean Chemical Society
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• v.23 no.12
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• pp.1769-1772
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• 2002

Previous $^{19}F\;and\;^{1,2}H$ electron-nuclear double resonance (ENDOR) study of fluorometmyoglobin (MbF) in frozen-solution state provided sensitive tools sensing subtle structural changes of the heme that are not obtainable from X-ray. [Fann et al., J. Am. Chem. Soc. 1995, 117, 6019] Because of the intrinsic inhomogeneouse EPR line broadening effect of MbF in frozen-solution state, detection of the intrinsic inhomogeneouse EPR line broadening effect of MbF in frozen-solution state, detection of the electronic and geometrical changes of the heme ring itself and the proximal histidine by using $^{14}N$ CW ENDOR was interfered. In the present study, hyperfine-sensitive $^{14}N$ Mims ENDOR technique of pulsed-EPR was employed to probe the changes. With two different $\tau$ values of 128 and 196 ns, $^{14}N$ ENDOR signals of the heme and proximal histidine were completely resolved at $g'_{II}(=g_e=2)$. This study present that X-band $^{14}N$ Mims ENDOR sequence can sensitively detect the small changes of the spin densities and p orbital populations of the proximal and the heme nitrogens, caused by ligand and pH variation of the distal site.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1179-1180
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• 2005

To immobilize the pollutants from wastewater in situ, two phosphatic clays collected from different areas in Egypt (eastern and western Sebaia, Aswan-Isna, Upper Egypt) used to remove contaminant ions from industrial wastewater. Obtained results confirmed the strong relationship between phosphatic clay and Pb elimination from wastewater. The sensitivity classification of phosphatic clay toward ions retained as described in three categories: highly sensitive to retain Pb , Al and Cr ; moderately sensitive for Mn; and weakly sensitive for Band Zn. Data suggested that large fraction of Pb removed by phosphatic clays stayed intact under a wide variation in extracting solution pH (3-11). In situ immobilization is considered a promising technique that has the potential to remove contaminant ions from wastewater. Two important factors need to be considered when applying this technique: The first, is the clay must be effective and selective under different composition of wastewater. The second, is the immobilized ions should be stable and non-leacheable under varying water conditions. Phosphatic clays with $Pb^{2+}$ were suitable to achieve these two factors. Possible mechanism for removal $Pb^{2+}$ by phosphatic clays is the formation of fluoropyromorphite through the dissolution of fluoro and hydroxyl apatite by its precipitation from solution, beside, Pb complexation at phosphatic clay surface at P-OH sites.

• Transactions on Electrical and Electronic Materials
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• v.9 no.6
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• pp.231-236
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• 2008

B, P, and Cs ions were implanted with various parameters into silicon nitride layers prepared by LPCVD. In order to get the maximum impurity concentration at the silicon nitride surface, a high temperature oxide (HTO) buffer layers was deposited prior to the implantation. Alkali ion and pH sensing properties of the layers were investigated with an electrolyte-insulator-silicon (EIS) structure using high frequency capacitance-voltage (HF-CV) measurements. The ion sensing properties of implanted silicon nitrides were compared to those of as-deposited silicon nitride. Band Cs co-implanted silicon nitrides showed a pronounced difference in pH and alkali ion sensing properties compared to those of as-deposited silicon nitride. B or P implanted silicon nitrides in contrast showed similar ion sensitivities like those of as-deposited silicon nitride.

• Journal of Microbiology and Biotechnology
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• v.21 no.5
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• pp.483-493
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• 2011

An acid phosphatase (HppA) activated by $NH_4Cl$ was purified 192- and 34-fold from the periplasmic and membrane fractions of Helicobacter pylori, respectively. SDS-polyacrylamide gel electrophoresis revealed that HppA from the latter appears to be several kilodaltons larger in molecular mass than from the former by about 24 kDa. Under acidic conditions (pH${\leq}$4.5), the enzyme activity was entirely dependent on the presence of certain mono- and/or divalent metal cations (e.g., $K^+$,$ NH_4{^+}$, and/or $Ni^{2+}$). In particular, $Ni^{2+}$ appeared to lower the enzyme's $K_m$ for the substrates, without changing $V_{max}$. The purified enzyme showed differential specificity against nucleotide substrates with pH; for example, the enzyme hydrolyzed adenosine nucleotides more rapidly at pH 5.5 than at pH 6.0, and vice versa for CTP or TTP. Analyses of the enzyme's N-terminal sequence and of an $HppA^-$ H. pylori mutant revealed that the purified enzyme is identical to rHppA, a cloned H. pylori class C acid phosphatase, and shown to be the sole bacterial 5'-nucleotidase uniquely activated by $NH_4Cl$. In contrast to wild type, $HppA^-$ H. pylori cells grew more slowly. Strikingly, they imported $Mg^{2+}$ at a markedly lowered rate, but assimilated urea rapidly, with a subsequent increase in extracellular pH. Moreover, mutant cells were much more sensitive to extracellular potassium ions, as well as to metronidazole, omeprazole, or thiophenol, with considerably lowered MIC values, than wild-type cells. From these data, we suggest that the role of the acid phosphatase HppA in H. pylori may extend beyond 5'-nucleotidase function to include cation-flux as well as pH regulation on the cell envelope.

• Korean Journal of Agricultural Science
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• v.5 no.2
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• pp.80-86
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• 1978

This study was carried out in order to know the effect of T. T. C. reaction on antibiotics, cleanser, disinfectants, pH, acidity and station of culture a bacterial Streptococcus thermophilus was used to 2.3.5-triphenyl tetrazolium chloride reduction test for the detection of residual antibiotics in milk were tested. The results obtained were summarized as follows. 1. The T. T. C. reaction was most sensitive in the group of penicillin as 0.02~0.05 IU and also it was less sensitive in Streptomycin and various broad antibiotics except Vibramycin, Synthomycin and Teramycin but it was least sensitive in Streptomycin group. 2. For ther T. T. C. reaction test on cleanser, the positive reaction was appeared above 0.7% of Hi-Ti and 0.1% of NaOH solution respectively. 3. For the T. T. C. test reaction on disinfectants, the positive reaction was occured on 200~500 ppm solution of sodium-hypochlorite and chloride-lime, 0.15~0.35% solution of phenol, cresol and Iode-K. 4. The optimum temperature was $35{\sim}37^{\circ}C$ and proper culturing time was 12 to 18 hours for propagation culturing. 5. The suspect positive reaction was tested above pH 5.0 and the positive reaction was appeared above 0.21% of acidity.

• Journal of Plant Biotechnology
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• v.6 no.4
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• pp.205-212
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• 2004

The objectives were to compare the salt tolerance levels in the parental rice cultivar, Dongjinbyeo, and induced mutagenesis derived its lines for plant height, MDA, ATPase, POD, and 2-dimensional protein electrophoresis pattern in NaCl-containing hydroponic nutrient solutions. Rice plants isolated from a population of rice (Oryza sativa L. cv. Dongjinbyeo) mutation lines, which were generated in combination with in vitro selection and gamma-ray, exhibited salt tolerance. Line No. 18 had the longest plant, whereas NaCl-sensitive line (No. 25) had the shortest plant. The parent, and the sensitive line showed severe damage from salt stress. Tolerant lines (No. 18, 50) had a lower malonaldehyde (MDA) content than the sensitive one (Dongjinbyeo, No. 25) during salt stress. Several proteins showed significant quantitative variation through 2DE; phosphoribulokinase, peroxidase, oxygen evolving enhancer 1 and the $H^+-ATPase$, which are known to be involved in salt tolerance. The effect of salt on peroxidase and $H^+-ATPase$ activity in the seedlings of two groups with contrasting genotypes of rice was studied. A greater activity was recorded in the tolerant lines as compared to the sensitive ones (P<0.05, Duncan's test). The results indicate that salt tolerant lines expressed more salt stress-inducible proteins associated with salt tolerance than the sensitive lines during salt stress.