• Journal of Food Hygiene and Safety
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• v.8 no.3
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• pp.163-169
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• 1993

The acute toxicity of lAS-Na(Linear Alkylbenzene Sulfonate-Na) and MES (ASME, Alpha-Sulfo fatty acid Methyl Ester), surfactans, was eyaluated in ICR mice for 14 days. Mice aging 6 weeks were administered orally with 0, 1,000, 1,320, 1,780, 2,280, 3,000 mg/kg of lASNa or 0, 1,000, 1,560, 2,450, 3,830, 6,000 mg/kg of MES in saline. The body weight of the treated animals was not significantly different from the controls. The main clinical signs of animals treated with lAS-Na or MES were diarrhea, decreased motor acthity and piloerection. The congestion in small intestine was only gross finding in dead animals treated with two sulfactants. In this study, $LD_{50}$ values of lAS-Na and MES were eyaluated 1,319 mg/kg in male and 1,402 mg/kg in female mice, 2,040 mg/kg in male and 2,548 mg in female mice, respectiyely.

• Journal of Microbiology and Biotechnology
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• v.11 no.2
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• pp.317-325
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• 2001

For heuristic purposes, the relative ratio of urease contents inside and outside cells was surveyed using nine ureB+ strains of Helicobacter pylori. the ratio of the enzyme specific activity appeared to vary greatly between the various H. pylori strains, ranging from 0.5 to 2.5. Besides the above compartment, urease was also richly found in the membrane fraction, especially in either peripheral or integral form. The urease distribution across the H. pylori membrane was significantly influenced by the ambient pH; the specific activity of external urease was highest at pH 5.5 with a narrow plateau, whereas the internal specific activity was highest within a pH range of 4.5 to 6.5 with a broad plateau. These finding strongly suggest that H. pylori urease is secretory and responded to the external pH. However, at pH 4.0 or below, no urease activity was detected in either the internal or external compartment, although an increase in the color development with 2,4,6-trinitrobenzene sulfonate (TNBS) was observed. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that these phenomena may be related to a specific proteolysis in certain proteins, including urease or ${\gamma}$-glutamyl transpeptidase. Interestingly, the effect of ammonium ions n alleviating the enzyme inactivation inside the H. pylori cells was remarkably similar to that of D-glucose. In addition, it would appear that the cation acted as a surrogate of not only $Na^+$ but also $K^+$ thereby increasing the H. pylori P-type ATPase activity. This is of great interest, as it implies that the urease action in H. pylori is indispensible at any locus.

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.507-513
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• 2017

Bacillus subtilis spores can be used for protein display to engineer protein properties. This method overcomes viability and protein-folding concerns associated with traditional protein display methods. Spores remain viable under extreme conditions and the genotype/phenotype connection remains intact. In addition, the natural sporulation process eliminates protein-folding concerns that are coupled to the target protein traveling through cell membranes. Furthermore, ATP-dependent chaperones are present to assist in protein folding. CotA was optimized as a whole-cell biocatalyst immobilized in an inert matrix of the spore. In general, proteins that are immobilized have advantages in biocatalysis. For example, the protein can be easily removed from the reaction and it is more stable. The aim is to improve the pH stability using spore display. The maximum activity of CotA is between pH 4 and 5 for the substrate ABTS (ABTS = diammonium 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate). However, the activity dramatically decreases at pH 4. The activity is not significantly altered at pH 5. A library of approximately 3,000 clones was screened. A E498G variant was identified to have a half-life of inactivation ($t_{1/2}$) at pH 4 that was 24.8 times greater compared with wt-CotA. In a previous investigation, a CotA library was screened for organic solvent resistance and a T480A mutant was found. Consequently, T480A/E498G-CotA was constructed and the $t_{1/2}$ was 62.1 times greater than wt-CotA. Finally, E498G-CotA and T480A/E498G-CotA yielded 3.7- and 5.3-fold more product than did wt-CotA after recycling the biocatalyst seven times over 42 h.

• Environmental Analysis Health and Toxicology
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• v.30 no.sup
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• pp.8.1-8.5
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• 2015

Objectives The objective of this study was to evaluate the biodegradation potential of four perfluorooctane sulfonic acid (PFOS) alternatives that were developed at Changwon National University. While PFOS has been used widely in industrial and consumer products, it is known to be a persistent organic pollutant. Therefore, greener alternatives are highly desirable. Methods Biodegradation tests were run for 28 days using standard test protocols. The biochemical oxygen demand was measured daily throughout the experimental period, and the data were used to calculate the biodegradation rates. Microorganisms were isolated from the some of the tests that showed evidence of biodegradation. Results $C_8H_8F_9KO_3S$, which has the same number of carbons as the parent compound PFOS but a reduced number of fluorines, showed the highest biodegradation rate followed by $C_{10}H_8F_{13}KO_3S$. Chemical alternatives with lower number of carbons did not biodegrade readily in the experiments. Conclusions Together, these results suggest that it may be advantageous to develop PFOS alternatives with 8 carbons, the same as PFOS, but a reduced number of fluorines; as such, chemicals are more susceptible to biodegradation than the parent compound.

• Environmental Analysis Health and Toxicology
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• v.22 no.2 s.57
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• pp.119-128
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• 2007

The present study was conducted to find out effect of PFOS on survival, activity, growth and organ structure of the melania snail, Semisulcospira gottschei. Experimental groups were composed of one control condition and four PFOS exposure condition (0.1, 0.5, 1.0 and 5.0 mg/L). After 16 week exposure, survival rate and activity were not significantly influenced at the two lower exposure groups, 0.1 and 0.5 mg/L, but they were significantly reduced in 1.0 and 5.0 mg/L groups. Total weight and meat weight rate (MWR) were reduced in PFOS exposure group in comparison to control group. Also, histological degenerations such as acidification of mucous, necrosis and split of muscular fiber bundle, atrophy of anterior pedal gland were recognized in the foot. Hepatopancreas showed the atrophy and degeneration of the digestive cell, vacuolation of digestive gland and closure of lumen in digestive gland.

• Journal of the Korean Applied Science and Technology
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• v.15 no.2
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• pp.77-81
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• 1998

Surface active properties of these aqueous Gemini surfactant solutions including surface tension, critical micelle concentration(cmc), foaming power, foam stability, emulsifying power and Krafft point were measured at given conditions. They showed excellent properties, being compared with conventional single-chain surfactants such as sodium dodecyl sulfonate(SDS). Their surface tensions in the aqueous solutions were decreased to $30{\sim}38$ mN/m, which is lower than 39 mN/m of SDS, and their cmc values evaluated by surface tension method were $2.8{\times}10^{-5}{\sim}3.3{\times}10^{-4}$ mol/L. These values were also much lower than that of SDS, $9.8{\times}10^{-3}$ mol/L. The foaming power and foam stability, especially decyl and dodecyl compounds, were good and the emulsifying power in benzene or soybean oil was also excellent. All of the synthesized Gemini surfactants possessed good water solubility and their Krafft points were all below $0^{\circ}C$. As results, DDED and DDOD, Gemini surfactants which were synthesized are expected to be applied as foamers, emulsifiers and so on.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.579-586
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• 2018

In this study, surfactants were synthesized using fatty alcohols of 8, 10, 12 and 14 carbon chains length. The structures of the synthesized surfactants was confirmed by FT-IR and $^1H$-NMR analysis. The surface tension of the diluted surfactant was measured as 26~32 mN/m depending on the carbon length and the critical micelle concentration was measured as $10^{-3}{\sim}10^{-5}mol/L$.The minimum value per molecule of the synthesized sulfonic acid surfactant is 1.68 to $1.30nm^2$. The physical properties of the synthesized surfactants were determined by measuring the critical micelle concentration, foaming power, emulsifying stability, and contact angle.

• Journal of Microbiology and Biotechnology
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• v.27 no.6
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• pp.1120-1127
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• 2017

Marasmius scorodonius secretes an extracellular laccase in potato dextrose broth, and this enzyme was purified up to 206-fold using $(NH_4)_2SO_4$ precipitation and a Hi-trap Q Sepharose column. The molecular mass of the purified laccase was estimated to be ~67 kDa by SDS-PAGE. The UV/vis spectrum of the enzyme was nontypical for laccases, and metal content analysis revealed that the enzyme contains 1 mole of Fe and Zn and 2 moles of Cu per mole of protein. The optimal pH for the enzymatic activity was 3.4, 4.0, and 4.6 with 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonate) (ABTS), guaiacol, and 2,6-dimethoxy phenol as the substrate, respectively. The optimal temperature of the enzyme was $75^{\circ}C$ with ABTS as the substrate. The enzyme was stable in the presence of some metal ions such as $Ca^{2+}$, $Cu^{2+}$, $Ni^{2+}$, $Mg^{2+}$, $Mn^{2+}$, $Ba^{2+}$, $Co^{2+}$, and $Zn^{2+}$ at a low concentration (1 mM), whereas $Fe^{2+}$ completely inhibited the enzymatic activity. The enzymatic reaction was strongly inhibited by metal chelators and thiol compounds except for EDTA. This enzyme directly decolorized Congo red, Malachite green, Crystal violet, and Methylene green dyes at various decolorization rates of 63-90%. In the presence of 1-hydroxybenzotriazole as a redox mediator, the decolorization of Reactive orange 16 and Remazol brilliant blue R was also achieved.

• YAKHAK HOEJI
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• v.49 no.4
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• pp.275-283
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• 2005

The purpose of the present study was to kinetically investigate the carrier-mediated uptake in the hepatic transport of organic anions, and to simulate the 'in vivo counter-transport' phenomena, using kinetic model which was developed in this study. The condition that the mobility of carrier-ligand complex is greater than that of free carrier is not essential for the occurrence of 'counter-transport' phenomenon. To examine the inhibitory effects on the initial uptake of organic anions by the liver, it is necessary to judge whether the true counter-transport mechanism (trans-stimulation) is working or not. Effects of bromophenol blue (BPB) or bromosulfophthalein (BSP) on the plasma disappearance curves of a 1-anilino-8-naphthalene sulfonate (ANS) were then kinetically analyzed based on a flow model, in which the ligand is eliminated only from the peripheral compartment (liver compartment). Moreover, 'in vivo counter-transport' phenomena were simulated based on the perfusion model which incorporated the carrier-mediated transport and the saturable intracellular binding. The 'in vivo counter-transport' phenomena in the hepatic transport of a organic anions were well demonstrated by incorporating the carrier-mediated process. However, the 'in vivo counter-transport' phenomena may be also explained by the enhancement of back diffusion due to the displacement of intracellular binding. In conclusion, one should be more cautious in interpreting data obtained from so-called 'in vivo counter-transport' experiments.

• Polymer(Korea)
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• v.36 no.3
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• pp.262-267
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• 2012

2-(1,3,3-Trimethyl-6-azabicyclo [3,2,1]-oct-6-yl)-4,5-dihydro-1,3-oxazoline (TAO) was polymerized at several conditions to clarify the influence of initiators, alkyl halide ($PhCH_2Br$, $PhCH_2Cl$, MeI) and sulfonate (MeOTf). The reactions were conducted at $100^{\circ}C$ for 24 h. The resultant polymer forms several kinds of structures with different combination of initiators. The sole MeOTf initiator caused chain transfer reaction to form the one-order structure for which the resultant polymer exclusively formed pendant structure, while alkyl halide and MeOTf formed two kinds of structures, pendant and main chain, which is caused by partly-proceeded double isomerization polymerization by highly reactive nucleophilic counter anion of halogen. Merrifield polymer was also utilized as an intiator and copolymerized with TAO, which produced a graft structure.