• 자연과학논문집
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• 제17권1호
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• pp.13-29
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• 2006

산화-환원 활성 단백질중에 하나인 설피레독신과의 결합 단백질을 효모 Two-hybrid 기법을 이용하여 탐색한 결과, 알파-만노시다제가 설피레독신과 특이적으로 결합함을 밝혔다. 알파-만노시다제는 D-만노스 당을 비환원성 말단으로부터 유리시키는 가수분해 효소로서, 세포 원형질에 다량체 형태로 존재한다. 본 연구에서는 설피레독신과 알파-만노시다제간의 단백질결합을 설피레독신의 새로운 생리기능 관점에서 토의했다.

• 대한지하수환경학회지
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• 제4권3호
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• pp.116-121
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• 1997

정화 효율과 운영상의 문제점을 파악하였다. 반응조 유입수 및 방류수에 대하여 현장에서 pH 및 Eh(산화환원전위)를 측정하였고 Cd, Pb, As, Zn, Cu, Fe, Al 및 Mn 등을 실험실에서 분석 하였다. 반응조 방류수에 대한 수질분석 결과 우분 및 석회석이 섞인 볏짚 반응조의 Cu, Zn, Fe, Cd, Al, Mn및 Pb의 정화효율(최대)은 98%, 100%, 99%, 100%, 97%, 61% 및 100%였고 이때 반응조의 수질환경은 pH 6 그리고 Eh 값이 -300 mV부근의 환원환경이었다. 그러나 시간이 경과함에 따라 Eh 값은 상승하였고 Al을 제외한 금속성분의 정화효율도 낮아져 반응조의 혐기환경유지는 금속성분의 정화에 매우 중요하였다. 반응조 시설을 운영한 결과 배관내의 산화물 Scale 및 기질물질의 부피 변화는 광산배수의 흐름을 방해하는 요소로 나타났다.

• Corrosion Science and Technology
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• 제3권5호
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• pp.198-208
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• 2004

Although there has been no general agreement on the mechanism of primary water stress corrosion cracking (PWSCC) as one of major degradation modes of Ni-base alloys in pressurized water reactors (PWR's), common postulation derived from previous studies is that the damage to the alloy substrate can be related to mass transport characteristics and/or repair properties of overlaid oxide film. Recently, it was shown that the oxide film structure and PWSCC initiation time as well as crack growth rate were systematically varied as a function of dissolved hydrogen concentration in high temperature water, supporting the postulation. In order to understand how the oxide film composition can vary with water chemistry, this study was conducted to characterize oxide films on Alloy 600 by an in-situ Raman spectroscopy. Based on both experimental and thermodynamic prediction results, Ni/NiO thermodynamic equilibrium condition was defined as a function of electrochemical potential and temperature. The results agree well with Attanasio et al.'s data by contact electrical resistance measurements. The anomalously high PWSCC growth rate consistently observed in the vicinity of Ni/NiO equilibrium is then attributed to weak thermodynamic stability of NiO. Redox-induced phase transition between Ni metal and NiO may undermine the integrity of NiO and enhance presumably the percolation of oxidizing environment through the oxide film, especially along grain boundaries. The redox-induced grain boundary oxide degradation mechanism has been postulated and will be tested by using the in-situ Raman facility.

• 접착 및 계면
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• 제15권1호
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• pp.1-8
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• 2014

이온 교환막은 전기투석, 확산투석, Redox flow 전지, 연료전지 등 다양하고 넓은 분야에서 사용되고 있다. 초음파를 이용하여 만들어진 PVC 양이온 교환막을 시간을 변화시켜 가면서 술폰화 반응에 의해 제조하였다. 술폰화제로 황산을 사용하였으며, 술폰화 PVC 양이온 교환막의 기본구조와 특성을 FT-IR, EDX, Water uptake, 이온교환용량(IEC), 전기저항(ER), 전도도, 이온수송수 및 표면 morphology를 SEM 분석하였다. FT-IR 스펙트럼 분석결과 술폰화 PVC 양이온 교환막에 술폰산기가 도입되었음을 확인하였으며 멤브레인의 Water uptake, IEC, 전기 저항 및 ion transport number의 최대값은 각각 40.2%, 0.87 meq/g, $35.2{\Omega}{\cdot}cm^2$ 및 0.88이었다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 춘계학술대회
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• pp.81-81
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• 2019

Ginseng seeds are one of short-lived seeds species which loose their viability easily in the condition of conventional storage. Cryopreservation using liquid nitrogen (LN) has been recommended as a alternative storage for this kind of germplasm short lived or dessiccation-sensitive. This study was performed to find out whether cryopreservation could affect physiological change such as enzyme activity induced by reactive oxygen species. In this work, the redox ratio of ascorbate and glutathione were examined onto ginseng seedlings before and after LN storage of seeds for 1 day using spectrophotometer method. Reduced ascorbate (ASA) was increased while oxidized ascorbate (DHA) was decreased slightly for both after 1d-LN storage. And for glutathione also, reduced form (GSH) was increased while oxidized form (GSSG) was decreased slightly for both after 1d-LN storage. Consequently total phenol compound and ion leakage after LN storage showed no significant differences. Additionally root growth from the seeds after LN storage was not affected by ultra low temperature. From the above results, we may suggest that cryopreservation could be recommended for storage tool of ginseng seeds even with low viability also and expected to make slower seed aging process during preservation period through further study.

• Journal of Microbiology and Biotechnology
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• 제33권3호
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• pp.378-386
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• 2023

The CYP707A family genes encoding ABA 8'-hydroxylase catabolize abscisic acid (ABA), a plant stress hormone that plays an important role in stress condition, such as drought, heat, cold and salinity. Phaseic acid (PA) is a catabolic product of ABA. Recent studies have shown that PA is important for the physiological functions in plants. It is also a neuroprotective molecule that protects against ischemic brain injury in mice. To obtain enzymes for the PA production, four CaCYP707A genes (CaCYP707A1, CaCYP707A2, CaCYP707A3 and CaCYP707A4) were isolated from hot pepper. They were heterologously expressed in Escherichia coli. Among them, CaCYP707A2 showed significantly higher expression levels in both the membrane fraction and the soluble fraction. Preferred redox partners were investigated to improve the efficiency of CaCYP707A2's catalytic reaction, and NADPH-cytochrome P450 reductase (CPR) from hot pepper (CaCPR) was preferred over other redox partners (i.e., rat CPR and ferredoxin reductase/ferredoxin). The production of 8'-hydroxy ABA and PA by ABA hydroxylation activity was confirmed in CaCYP707A2 from both membrane and soluble fractions. Therefore, CaCYP707A2 is the first identified plant CYP protein that is expressed a soluble form in cytosolic fraction having stable activity. Taken together, we propose a new CYP707A protein with industrial applications for PA production without additional modifications in E. coli heterologous expression.

• 대한수의학회지
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• 제37권3호
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• pp.547-554
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• 1997

Galectin-3 is known as an animal ${\beta}$-galactoside-binding lectin charicterized with S-type carbohydrate recognition domain. It plays a role in growth, adherence and movement of cells. It is, also, related to the cell transformation and metastasis of tumor cells. In this study, we have expressed and purified recombinant human galectin-3 (rHgalectin-3) using E coli system and asialofetuin affinity chromatography for the future development of monoclonal antibody to Hgalectin-3, which is suggested as the tumor marker for the gastric and thyroid gland cancers. Expressed protein was confirmed as the Hgalectin-3 by immunoblot with cross-reactive murine monoclonal antibody. Lectin activity and specificity of purified protein were, also, confirmed by the competitive inhibition with galectin-3 specific carbohydrate, lactose. Like physiological galectin-3, lectin activity of the molecule was not changed in nonreduced condition. Dimer formation, furthermore, was observed at high concentration of the protein even in the reduced condition, which is well known in physiological galectin-3. These results showed purified rHgalectin-3 has the same activity and molecular nature compared to the physiological galectin-3.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1290-1296
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• 2012

Fenton reaction and iron autoxidation have been debated for the major process in ROS mediated DNA cleavage. We compared both processes on iron oxidation, DNA cleavage, and cyclic voltammetric experiment at different pHs. Both oxidation reactions were preferred at basic pH condition, unlike DNA cleavage. This indicates that iron oxidation and the following steps probably occur separately. The ROS generated from autoxidation seems to be superoxide radical since sod exerted the best inhibition on DNA cleavage when $H_2O_2$ was absent. In comparison of cyclic voltammograms of $Fe^{2+}$ in NaCl solution and phosphate buffer, DNA addition to phosphate buffer induced significant change in the redox cycle of iron, indicating that iron may bind DNA as a complex with phosphate. Different pulse voltammogram in the presence of ctDNA suggest that iron ions are recyclable at acidic pH, whereas they may form an electrically stable complex with DNA at high pH condition.

• Bulletin of the Korean Chemical Society
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• 제16권6호
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• pp.511-515
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• 1995

Since much studies have been performed concerning the electrochemical behaviors and the practical applications of PB based devices, little has yet reported to investigate the best condition for the preparation for PB thin films. As considered some factors(peak shape, peak current, and peak separation) from the i-V curves, the optimal condition in the film growth were investigated under various immersion solutions. An electron-transfer processes of Fe2+/Fe3+ and Fe(CN)63-/4- redox couples were considered by measuring the observed currents as a function of the rotation velocity. The standard heterogeneous electron-transfer rates for these films and bare Au disc electrode in 10-3 M Fe2+/Fe3+ solution, applied at +0.65 V vs. SCE, were 6.14 × 10-3 and 7.78 × 10-3 cm/s, respectively, obtained using a rotating disc electrode. In case of the addition of potassium ion, the rate constants for these Fe2+/Fe3+ system on thin films of PB and bare electrode were given a little high values. The electron transfer rate for 10-3 M Fe(CN)63-/4- were 4.55 × 10-3 and 6.84 × 10-3 cm/s, respectively. The conductivity as directly determined during obtained the voltammogram, was 2.2 × 10-7 (Ω·cm)-1. This value is similar magnitude to that calculated from bulk sample.

• 한국환경농학회지
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• 제28권2호
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• pp.165-170
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• 2009

환원상태가 발달된 담수상태의 토양이나 습지생태계에서 $NO_3^-$는 환원상태의 진전을 지연시키는 완충역할을 할 수 있다. 논토양에서 $NO_3^-$가 Fe의 환원과 그에 따른 P의 가용화에 미치는 영향을 조사하였다. 담수 후 10 cm 깊이 토양의 산화환원전위 변화는 $NO_3^-$를 처리한 토양과 처리하지 않은 토양에서 현저하게 달리 나타났으며, $NO_3^-$의 환원이 일어나는 동안에는 산화환원전위가 330${\sim}$360 mV 범위에서 유지되었다. 그리고 이 기간 동안 Fe의 환원은 현저히 억제되었다. $NO_3^-$를 처리한 토양 용액의 $PO_4^{3-}$ 함량은 담수 이후 0.2${\sim}$0.3 mg/L 수준 또는 그 이하로 유지되었으며, 반면 $NO_3^-$를 처리하지 않은 경우에는 담수 후 9일째부터 Fe의 환원과 함께 토양 용액의 $PO_4^{3-}$ 함량이 급격히 증가하였다. 일반적인 토양에서 무기태 P의 상당부분이 Fe 산화물에 고정된 형태 및 Fe와 결합된 형태로 존재하므로 Fe의 환원에 따라서 $PO_4^{3-}$가 함께 용출되는 것이다. 이상의 결과를 보면 토양중의 $NO_3^-$가 $Fe^{2+}$와 $PO_4^{3-}$의 용출을 조절하는 요인인 것으로 확인할 수 있다. 토양 용액중의 $NO_3^-$ 농도가 1 mg/L 이상으로 유지되는 상태에서는 토양의 산화환원전위가 330 mV 이하로 낮아지지 못하며, 따라서 Fe의 환원과 그에 따른 P의 용출 또한 현저히 억제되는 것으로 판단된다.