• Corrosion Science and Technology
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• 제9권3호
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• pp.137-141
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• 2010

Sodium nitrite is widely used as one of the popular corrosion inhibitors for the protection of ferrous metal in closed cooling water system, such as a diesel engine and a chiller. The optimum treatment conditions are studied through laboratory tests using linear polarization resistance (LPR) technique. Corrosion rate of the carbon steel electrode could be maintained less than $2.5{\times}10^{-3}$ mmpy in the test condition of 500 ppm as ${NO_2}^-$, 200 ppm as $Cl^-$, $70^{\circ}C$ and pH 6.8. The pH control is confirmed not to be an important factor in the protection of carbon steel by sodium nitrite inhibitor. The addition of tolyltriazole was needed for the protection of the copper alloy in the sodium nitrite treatment system.

• BMB Reports
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• 제35권3호
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• pp.302-305
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• 2002

Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at $27^{\circ}C$ using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to $140\;{\mu}M$ by the microcalorimetry method, which agrees well with the value of $143\;{\mu}M$ for the inhibition constant that was obtained from the spectroscopy method.

• 상하수도학회지
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• 제21권6호
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• pp.727-735
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• 2007

The use of water by cities is increasing owing to industrialization, the concentration of population, and the enhancement of the standard of living. Accordingly, the amount of waste water is also increasing, and the degree of pollution of the water system is rising. In order to solve this problem, it is necessary to remove organisms and suspended particles as well as the products of eutrophication such as nitrates and phosphates. This study developed a high-end treatment engineering solution with maximum efficiency and lower costs by researching and developing a advanced treatment engineering solution with the use of Biosorption. As a result, the study conducted a test with a $50m^3/day$ Pilot Scale Plant by developing treatment engineering so that only the secondary treatment satisfies the standard of water quality and which provided optimal treatment efficiency along with convenient maintenance and management. The removal of organisms, which has to be pursued first for realizing nitrification during the test period, was made in such a way that there would be no oxidation by microorganisms in the reactor while preparing oxygen as an inhibitor for the growth of microorganism in the course of moving toward the primary settling pond. The study introduced microorganisms in the endogeneous respiration stage to perform adhesion, absorption, and filtering by bringing them into contact with the inflowing water with the use of a sludge returning from the secondary settling pond. Also a test was conducted to determine how effective the microorganisms are as an inner source of carbon. The HRT(Hydraulic Retention Time) in the nitrification tank (aerobic tank) could be reduced to two hours or below, and the stable treatment efficiency of the process using the organisms absorbed in the NAR reactor as a source of carbon could be proven. Also, given that the anaerobic condition of the pre-treatment tank becomes basic in the area of phosphate discharge, it was found that there was excellent efficiency for the removal of phosphate when the pre-treatment tank induced the discharge of phosphate and the polishing reactor induced the uptake of phosphate. The removal efficiency was shown to be about 94.4% for $BOD_5$. 90.7% for $COD_{Cr}$ 84.3% for $COD_{Mn}$, 96.0% for SS, 77.3% for TN, and 96.0% for TP.

• Journal of Plant Biotechnology
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• 제32권2호
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• pp.97-103
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• 2005

Superoxide dismutase와 ascorbate peroxidase가 동시에 과대발현된 담배(CA)를 가지고 여러 제초제들에 대한 항산화 반응을 조사하였다. 온실조건 실험에서, CA 담배는 PSI 저해제로 알려진 paraquat처리에 대해서 내성이 인정되었고 그 정도는 40% 내외였다. PS II 저해제 (bromoxynil, diuron, bromacil), 엽록소 생합성 저해제 (oxyfluorfen), 카로티노이드 생합성 저해제 (fluridone)와 EPSP synthase 저해제 (glyphosate) 처리에서는 CA와 wild type간의 반응차이가 관찰되지 않았다. Paraquat와 diuron을 이용한 약광 조건의 실험에서도 온실조건의 실험결과와 유사한 정도로 paraquat처리에 대해서만 내성을 나타내었다. 온실조건에서의 엽위별 반응의 경우, 6 - 9 엽기 식물체에 paraquat를 처리하였을 때, 약제처리 당시 위로부터 3 - 4번째 전개되고 있었던 잎이 상대적으로 내성 정도가 높게 나타났다. 한편 paraquat 처리 시에 여러 농도의 ascorbic acid를 혼합할 경우, CA와 wild type 모두에서 비슷한 정도로 paraquat 활성을 경감시켰다. 결론적으로, CuZnSOD/APX의 과대발현은 photosystem I 에서 발생되는 산화스트레스에 대해서만 주로 작용하며, 다른 제초제들에 의해 발생되는 산화적 스트레스에 대해서는 소거 능력이 부족한 것으로 판단되었다.

• 한국미생물·생명공학회지
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• 제12권4호
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• pp.277-283
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• 1984

제방 효모로 부터 분리 정제한 adenylate kinase 는 한개의 기질에 의해 또 하나의 기질 결합을ADP생성 반응에서는 4배, AMP와 Mg·ATP 생성에서는 2배 촉진되었다. 기질 특이성에 있어서는 nucleotide monophosphale일 경우 dAMP만이 활성을 보여주었으며 nucleotide triphosphate일 경우 ATP이외 UTP, ITP, GTP의 순위로 활성이 높았다. AMP와 Mg·ATP가 기질일 경우 과잉의 AMP는 pH 7.2와 pH8.0에서는 Mg·ATP에 경쟁적으로 저해하였으며 pH가 높을수록 그 Ki정수는 낮았다. Phosphoenolpyruvate는 AMP에 대해 경쟁적 Mg·ATP에 대해서는 비 경쟁적 저해제 이었으며 Adenosine pentaphosphoadenosine은 모든 기질에 대해 경쟁적 저해제로 작용하였다. 제빵 효모로부터의 adenylate kinase는 아미노산 조성에 있어서 동물의 Mitochondria형에 가까우며 Ito등의 결과와 일치하지 않았다. 상기와 같은 효소학적 성질을 종합 고찰한 결과 효모 adenylate kinase는 동물의 Mitochondria형 효소로 분류할 수 있으며 효모 adenylate kinase에 있어 연구자 상호간의 차이점은 사용한 균주의 차이에 기인하는 것으로 생각된다.

• 대한화학회지
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• 제39권6호
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• pp.459-465
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• 1995

효모 acetolactate synthase를 분리 정제하여 기본적인 생화학적 성질에 대한 연구를 수행하였다. 효모를 0.5% glucose, 51 mM $K_2HPO_4$, 22 mM $KH_2PO_4$, 8mM$(NH_4)2SO_4,\;0.4\;m M\;MgSO_4$를 포함하는 최소 배지에서 37$^{\circ}C$로 18시간 동안 배양하였다. 배양된 세포들을 원심분리법으로 수학해 0.1 mM TPP, 0.5 mM DTT, 1${\mu}M$ FAD와 1mM MgCl_2$를 포함하는 20 mM phosphate 완충용액(pH 7.0)에 현탁시켜 하룻밤 동안 방치하였다. 효모를 파쇄한 후 이것의 $10,000{\times}g$ 상충액을 모아 ammonium sulfate 분별 침전법과 DEAE-Se-phacel 그리고 leucine-agarose chromatography법을 이용하여 부분 정제하였다. 단백질의 농도, 시간, 온도, pH, 기질농도 등의 영향을 조사하였으며 측정한 결과 최적온도는 50$^{\circ}C$이고, pH 8.0∼8.5 사이에서 최고 값을 나타냈다. $K_m$과 $V_{max}$값은 각각 8.4 mM과 17.9 nmol/mg/min으로 얻어졌다. 효소의 안정성은 ethylene glycol과 glycerol의 존재하에서 크게 향상됨이 관찰되었다. Feedback inhibition 연구 결과 Val에 의해 가장 많은 영향을 받았고 Leu에는 거의 영향을 받지 않았다.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.65-71
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• 2009

Microbial oxidoreductive systems have been widely used in asymmetric syntheses of optically active alcohols. However, when reused in multi-batch reaction, the catalytic efficiency and sustainability of non-growing cells usually decreased because of continuous consumption of required cofactors during the reaction process. A novel method for NADPH regeneration in cells was proposed by using pentose metabolism in microorganisms. Addition of D-xylose, L-arabinose, or D-ribose to the reaction significantly improved the conversion efficiency of deracemization of racemic 1-phenyl-1,2-ethanediol to (S)-isomer by Candida parapsilosis cells already used once, which afforded the product with high optical purity over 97%e.e. in high yield over 85% under an increased substrate concentration of 15 g/l. Compared with reactions without xylose, xylose added to multi-batch reactions had no influence on the activity of the enzyme catalyzing the key step in deracemization, but performed a promoting effect on the recovery of the metabolic activity of the non-growing cells with its consumption in each batch. The detection of activities of xylose reductase and xylitol dehydrogenase from cell-free extract of C. parapsilosis made xylose metabolism feasible in cells, and the depression of the pentose phosphate pathway inhibitor to this reaction further indicated that xylose facilitated the NADPH-required deracemization through the pentose phosphate pathway in C. parapsilosis. moreover, by investigating the cofactor pool, the xylose addition in reaction batches giving more NADPH, compared with those without xylose, suggested that the higher catalytic efficiency and sustainability of C. parapsilosis non-growing cells had resulted from xylose metabolism recycling NADPH for the deracemization.

• The Korean Journal of Physiology and Pharmacology
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• 제3권5호
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• pp.529-538
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• 1999

This study was undertaken to examine the effect of ethanol on $Na^+ -dependent$ phosphate $(Na^+-P_i)$ uptake in opossum kidney (OK) cells, an established renal proximal tubular cell line. Ethanol inhibited ^Na^+-dependent$ component of phosphate uptake in a dose-dependent manner with $I_{50}$ of 8.4%, but it did not affect $Na^+-independent$ component. Similarly, ethanol inhibited $Na^+-dependent$ uptakes of glucose and amino acids (AIB, glycine, alanine, and leucine). Microsomal $Na^+-K^+-ATPase$ activity was not significantly altered when cells were treated with 8% ethanol. Kinetic analysis showed that ethanol increased $K_m$ without a change in $V_{max}$ of $Na^+-P_i$ uptake. Inhibitory effect of n-alcohols on $Na^+-P_i$ uptake was dependent on the length of the hydrocarbon chain, and it resulted from the binding of one molecule of alcohol, as indicated by the Hill coefficient (n) of 0.8-1.04. Catalase significantly prevented the inhibition, but superoxide dismutase and hydroxyl radical scavengers did not alter the ethanol effect. A potent antioxidant DPPD and iron chelators did not prevent the inhibition. Pyrazole, an inhibitor of alcohol dehydrogenase, did not attenuate ethanol-induced inhibition of $Na^+-P_i$ uptake, but it prevented ethanol-induced cell death. These results suggest that ethanol may inhibit $Na^+-P_i$ uptake through a direct action on the carrier protein, although the transport system is affected by alterations in the lipid environment of the membrane.

• Korean Chemical Engineering Research
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• 제53권4호
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• pp.457-462
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• 2015

헤미셀룰로오스 가수분해액은 당은 물론 카르복시산, 푸란유도체 및 페놀화합물과 같은 여러 종류의 에탄올 발효 저해물질을 포함한다. 본 연구에서는 이런 저해물질들을 제거할 수 있는 분리 기술로서 에멀젼형 액막법이 적용되었다. 기본 모사 헤미셀룰로오스 가수분해액은 당인 자일로스, 용매인 묽은 황산 수용액과 카르복시산인 초산으로 구성되었으며, 필요에 따라 푸란유도체인 푸르푸랄 또는 페놀화합물인 p-hydroxybenzoic acid(HBA)가 그 가수분해액에 추가되었다. 본 연구에서 고려된 모든 에멀젼형 액막계에서 약산인 초산과 HBA는 선택적으로 제거가 가능하였지만, 알데히드인 푸르푸랄은 상당히 제거하기가 어려웠다. 또한, 기본 모사 가수분해액에 HBA가 추가된 에멀젼형 액막계에서 추출제로 tributyl phosphate를 사용하여 원료상에 있는 초산과 HBA를 99%까지 동시에 선택적으로 제거할 수 있었다.

• Archives of Pharmacal Research
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• 제29권11호
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• pp.1049-1054
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• 2006

Activation of Sphingosine kinase (Sphk) increases a bioactive lipid, sphingosine 1-phosphate (S1P) and has been observed in a variety of cancer cells. Therefore, inhibition of Sphk activity was an important target for the development of anticancer drugs. As a searching tool for Sphk inhibitor, we developed fluorescent Sphk activity assay combined with high performance liquid chromatography (HPLC). Previously we established murine teraticarcinoma mutant F9-12 cells which lack S1P lyase and stably express Sphk1. By using F9-12 cells, optimal assay conditions were established as follows; $100\;{\mu}M\;of\;C_{17}-Sph\;and\;30\;{\mu}g$ protein of F9-12 cells lysate in 20 min. Sphingosine analog $C_{17}-Sph$ was efficiently phosphorylated by Sphk activity ($K_{m}:67.08\;{\mu}M,\;V_{max}\;:1507.5\;pmol/min/mg$). New product $C_{17}-S1P$ was separated from S1P in reversed-phase HPLC. In optimized conditions, 300 nM of phorbol 12-myristate 13-acetate (PMA) increased Sphk activity approximately twice while $20\;{\mu}M$ of N,N-dimethylsphingosine (DMS) reduced 70% of Sphk activity in F9-12 cells lysate. In conclusion, we established non-radioactive but convenient Sphk assay system by using HPLC and F9-12 cells.