• 미생물학회지
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• 제31권4호
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• pp.261-266
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• 1993

유일한 탄소 및 에어지원으로 메탄올만을 이용하여 성장하는 새로운 절대 메탄올 자화세균을 토양으로 부터 분리하였다. 분리균주는 그람음성의 운동성이 없고 포자를 형성하지 않는 간균으로 정대호기성 세균이었다. 이 균주는 catalase 활성과 oxidase 활성을 가지고 있으며, nitrate를 nitrite로 환원시킬 수 있고 성장시 vitamin이나 특이한 생육인자를 요구하지 않았다. 세대시간은 1.6시간으로 메탄올 동화경로로는 ribulose monophosphate pathway(Entner-Doudoroff 변형경로)를 이용하나 α-ketoglutarate dehydrogenase 활성은 없었다. Ammonium ion은 glutamate dehydrogenase를 이용하여 동화하였다. DNA의 guanine plus cytosine 함량은 61.0 mol%이고 세포내 지방산으로는 누고 straight-chain saturated C$^{16:0}$ acids(palmitie acids)와 unsaturated C$^{16:1}$ acids(palmitoleic acids)를 가지고 있으나 이외에도 두 종류의 unidentified C$_{17}$ branched fatty acid도 포함하고 있었다. Major ubiquinone은 Q-8이나 Q-6와 Q-7을 특이하게 소량 가지고 있었다. Phospatidylethanolamine과 Phosphatidylglycerol이 주요한 phospholip의 구성물질이나 diphosphatidylgycerol도 소량 포함하고 있었다. 위와같은 생리적, 생화학적 자료로 부터 분리균주를 새로은 종 즉, Methylohacillus methanolovorus sp. nov.로 명명하였다.

• Corrosion Science and Technology
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• 제7권1호
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• pp.40-44
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• 2008

Passive metal forms an interfacial diffuse layer on the surface of passive film by its reaction with $H^+$ or $OH^-$ ions in solution depending on solution pH. There is a critical pH, called pH point of iso-selectivity ($pH_{pis}$) at which the nature of the diffuse layer is changed from the anion-permeable at pH<$pH_{pis}$ to the cation-permeable at pH>$pH_{pis}$. The $pH_{pis}$ for a passivated Fe was determined by examining the effects of pH on the thickness of passive film and on the dissolution reaction occurring on the passive film under a gavanostatic reduction in borate-phosphate buffer solutions at various pH of 7~11. The steady-state thickness of passive film formed on Fe showed the maximum at pH 8.5~9, and further the nature of film dissolution reaction was changed from a reaction producing $Fe^{3+}$ ion at $pH\leq8.5$ to that producing $FeO_2{^-}$ at $pH\geq9$, suggesting that the $pH_{pis}$ of Fe is about pH 8.5~9. In addition, the passive film formed at pH 8.5~9, $pH_{pis}$, was found to be the most protective with the lowest defect density as confirmed by the Mott-Schottky analysis. Pitting potential was decreased with increasing $Cl^-$ concentration at $pH\leq8.5$ due probably to the formation of anion permeable diffuse layer, but it was almost constant at $pH\geq9$ irrespective of $Cl^-$ concentration due primarily to the formation of cation permeable diffuse layer on the film, confirming again that $pH_{pis}$ of Fe is 8.5~9.

• 미생물학회지
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• 제6권2호
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• pp.54-62
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• 1968

The effect of gamma-ray on yeast cells Sacch. cerevisiae, and the leakage of cellular constituents such as carbohydrates, ribose, amino acids, inorganic phosphates and organic phosphates have been studied. The samples of yeast cells washed throughly and starved intensively, radiation effects were compared with those of control (un-starved), the irradiation dose rates are in the range from 24 Kr. up. to 480, Kr. The loss of 260m$\mu$. absorbing material, are also observed. Mechanisms of membrane damage by gamma-irradiation are discussed corelating to permeability changes and loss of substances, then active and passive transport process are also under considerations in discussion. The experimental results are as follows, 1. Carbohydrates of yeast cell leak out by gamma-irradiation, and amounts of loss increase proportionally as the increasing of radiation dose, curve of carbohydrates loss in starved cells is parallel with those of non-starved cells. 2. Ribose leak out less than that of carbohydrate from irradiated cell, the dose response curve of loss is straight and proportional to the increasing of radiation doses, slope of the curve is much lower than of carbohydrates. 3. Amino acids also leak out and the curve of losses to radiation is not proportional, it is revealed that there are little losses from yeast at lower doses of irradiation. 4. The losses of inorganic phosphates increase unproportionally to the increasing of irradiation doses, there are little leakage at the lower doses of irradiation. The losses of organic phosphates increase proportionally to the increasing of irradiation doses, and the amount of losses are much more than that of inorganic phosphate at lower doses of irradiation. 5. Leakage from irradiated yeast cells was shown to be due to passive transport process not an energy requiring process of ion transport. 6. Loss of 260 m$\mu$. absorbing material is little more than that of control yeast by the gamma-irradiation dose of 120K.r. and 240K.r.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.55-55
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• 2003

P2X$_3$ receptor, a member of P2 purine receptors, is a ligand-gated ion channel activated by extracellular ATP as an endogenous ligand, and highly localized in peripheral and central sensory neurons. The activation of P2X3 receptor by ATP as the pronociceptive effect has been known to initiate the pain signaling involved in chronic inflammatory nociception and neuropathic pain by nerve injury, implicating the possibility of new drug development to control pains. In this study, we have developed a two electrode voltage clamp (TEVC) assay system to evaluate the inhibitory activity of several newly synthesized PPADS and a novel non-ionic antagonist against ATP activation of human P2X3 receptor. PPADS derivatives include several pyridoxine and pyridoxic acid analogs to study the effects of phosphate and aldehyde functional groups in PPADS. All new PPADS analogs were less potent than PPADS at human P2X$_3$ receptors, however, LDD130, a non-ionic analog showed potent antagonistic property with $IC_{50}$/ of 8.34 pM. In order to uncover the structure activity relationships of LDD130, and design new structural analogs, we synthesized and investigated a few structural variants of LDD130, and the results will be discussed in this presentation.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1601-1608
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• 2010

A scandium(III) porphyrin-based fluoride-selective potentiometric sensor and its application in the analysis of hydrofluoric acid is described. Scandium(III) octaethylporphyrin, an ionophore recently developed for the optical fluoride sensor, was employed as a host molecule for the selective binding with fluoride in the plasticized PVC membrane. Nernstian response for $F^-$ between $10^{-4.6}$ to $10^{-1}$ M was observed at a glycine-phosphate buffer (pH 3.0). The selectivity pattern was observed as $F^-$, salicylate $\gg$ $SCN^-$ > $Cl^-$, $Br^-$, $NO_3{^-}$, $ClO_4{^-}$, which is consistent with the binding constant data measured in the plasticized PVC membrane based on a sandwich membrane method. This highly selective and reversible fluoride-sensitive electrode was employed for the analysis of hydrofluoric acid (HF). A disposable differential-type HF sensor was fabricated on the screen-printed electrode and demonstrated its ability to detect the neutral HF in the acidic solution.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.728-734
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• 2011

$LiFePO_4$ is a promising cathode material for secondary lithium batteries due to its high energy density, low cost and safety. $LiFePO_4$ was synthesized by the citrate process under reductive, neutral, and oxidative, atmospheres and the crystal structure was analyzed by X-ray powder diffraction. The samples synthesized under $N_2$ and $H_2$ atmosphere showed a single phase of a olivine structure, where the samples synthesized under $O_2$ atmosphere exhibited second phase of $Fe2O_3$. All the samples synthesized at 400, 600 and $800^{\circ}C$ under $N_2$ atmosphere presented a single phase of olivine. Residual organic material was observed for the sample synthesized at $400^{\circ}C$. There was nearly no intensity difference between the samples synthesized at $600^{\circ}C$ and $800^{\circ}C$. The electrochemical characteristic of the $LiFePO_4$ synthesized at $600^{\circ}C$ in the $N_2$ atmosphere was analyzed. The result exhibited an high discharge capacity of 160 mAh/g at the first cycle, and 155-160 mAh/g after 45 cycles.

• 대한화학회지
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• 제36권3호
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• pp.393-404
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• 1992

새로운 효소반응기를 쓰는 요소 정량용 연속${\cdot}$자동화 장치의 감응성질을 조사하였다. 효소반응기는 지지체인 nylon-6입자(42∼48 mesh)를 teflon관(안지름 2mm, 길이 20cm)에 충전시키고, 이 지지체의 표면에 공유결합제인 glutaraldehyde로 urease를 고정화시켜서 제작하였다. 연속${\cdot}$자동화장치는 효소반응기, 기체투석기 및 지시전극인 관형 PVC-nonactin막 암모늄 이온 선택성 전극을 차례로 연결하여 만들었다. 이 장치를 써서 요소를 정량할 때 감응특성은 다음과 같다. 곧 직선감응 농도범위는 $5.5{\times}10^{-6}$~$2.4{\times}10^{-3}M$, 감응기울기는 57.8 mV/decade, 검출한계는 $1.5{\times}10^{-6}M$, 효소반응기의 전환백분율은 80.8%이었다. 효소반응기의 최적 완충용액은 0.01M Tris-HCl 완충용액(pH 7.0∼7.8)과 0.01M 인산염 완충용액(pH 6.9∼7.5)이었고, 수명은 150일 정도였다. 또한 다른 생리활성물질의 방해는 없었다.

• KSBB Journal
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• 제19권6호
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• pp.451-456
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• 2004

교반배양시 배지에 첨가되는 에탄올의 농도가 증가할수록 $Cel^-$ mutant의 발생율이 증가하므로 $1.5\%$ 에탄올이 첨가된 배지의 경우 500 rpm보다 높은 교반속도를 유지해야 효과적으로 $Cel^-$ mutant의 발생이 억제되고 BC 생산량을 증가시킬 수 있다. 교반 배양과 같은 강한 shear stress의 배양환경 하에서는 진탕배양의 경우와 달리 $1.0\%$ 에탄올을 분할공급하더라도 BC 생산의 효율성을 높일 수 없었다. Phosphate ion이 첨가된 배지보다 첨가되지 않은 배지에서 BC 생산량이 더 높았다. 배지조성 중 아세트산의 농도를 $1.0\%$로 증가시키면 균체의 건조중량은 변화가 없었으나 BC 생산량이 감소되었다. 배양액의 pH 제어는 BC의 생산에는 영향을 미치지 않았으나 균체의 성장과 WSPS의 생산을 향상시켰다.

• Preventive Nutrition and Food Science
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• 제1권1호
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• pp.111-116
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• 1996

Polyphenol oxidase(PPO) isolated from the crude extract of ascidian, Halocynthia roretzi, showed higher affinity for catechol than tyrosine or DL-DOPA. Successful enzyme assay could be performed at $25^{\circ}C$, 10min. by mixing 0.2ml of crude enzyme extract with 2.8ml of 0.13M catechol in 0.1M sodium phosphate buffer(pH 6.4). The specific activity of PPO which had been purified with a combination of ammonium sulfate treatment, ion exchange chromatography on DEAE-cellulose, and gel filtration on Sepharose 6B was 13-fold disc gel electrophoresis. The activity of PPO was stable from pH 5.0 to 8.0 and showed the peak activity at pH 6.4 .The optimum reaction temperature for PPO oxidation on catechol was 35$^{\circ}C$ and those enzyme were heat stable up to 4$0^{\circ}C$. Molecular weigth of the enzyme was estimated about 170kDa. One molecule was found to be composed of gour subunits. Two of them had molecular weigh of 55kDa and the others 30kDa. The {TEX}$K_{m}${/TEX} values, {TEX}$V_{max}${/TEX} and catalytic efficiency({TEX}$V_{max}${/TEX}/{TEX}$K_{m}${/TEX}) for catechol were 0.12mM, 2.5mM/liter/min. and {TEX}$0.18min^{-1}${/TEX} respectively. The substrate affinity and electrophorectic pattern suggested that the enzyme of ascidian was considered to be not tyosine but catechol oxidase.

• The Plant Pathology Journal
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• 제37권6호
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• pp.566-579
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• 2021

Ralstonia syzygii subsp. indonesiensis (Rsi, former name: Ralstonia solanacearum phylotype IV) PW1001, a causal agent of potato wilt disease, induces hypersensitive response (HR) on its non-host eggplant (Solanum melongena cv. Senryo-nigou). The disaccharide trehalose is involved in abiotic and biotic stress tolerance in many organisms. We found that trehalose is required for eliciting HR on eggplant by plant pathogen Rsi PW1001. In R. solanacearum, it is known that the OtsA/OtsB pathway is the dominant trehalose synthesis pathway, and otsA and otsB encode trehalose-6-phosphate (T6P) synthase and T6P phosphatase, respectively. We generated otsA and otsB mutant strains and found that these mutant strains reduced the bacterial trehalose concentration and HR induction on eggplant leaves compared to wild-type. Trehalose functions intracellularly in Rsi PW1001 because addition of exogenous trehalose did not affect the HR level and ion leakage. Requirement of trehalose in HR induction is not common in R. solanacearum species complex because mutation of otsA in Ralstonia pseudosolanacearum (former name: Ralstonia solanacearum phylotype I) RS1002 did not affect HR on the leaves of its non-host tobacco and wild eggplant Solanum torvum. Further, we also found that each otsA and otsB mutant had reduced ability to grow in a medium containing NaCl and sucrose, indicating that trehalose also has an important role in osmotic stress tolerance.