• Journal of Plant Biology
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• 제34권4호
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• pp.303-309
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• 1991

Limitation of photosynthesis in detached Chinese cabbage (Brassica campestris L.) leaves was induced by feeding of mannose (25 mM) for 12 h in the light, and changes in the basic thylakoid functions under this condition were investigated. The acid soluble phosphate contend and CO2 uptake rate was decreased by 66% and 67%, respectively. However, the starch content was increased by 24% compared to those of controls. From the fast induction curves of chlorophyll fluorescence, dark level fluorescence (Fo) slightly increased while intermediate plateau fluorescence level (FI) to peak level fluorescence (Fp) transient was significantly decreased with a slight decrease in the Fo-to-FI transient. This data means that reduction of secondary electron acceptor of PSII (QB) might be more severely inhibited than that of primary electron acceptor of PSII (QA) by decrease in phosphate level. The strong decline of (Fv)m//Fm ratio suggests that efficiency of excitation energy capture by PSII was decreased markedly. The quenching of Fo (qO), an indicator of state transition, was also occurred over the slow induction kinetics of chlorophyll fluorescence. From quenching analysis, fluorescence was dominantly quenched by nonphotochemical quenchings (qE+qT). These results showed that the capture and transfer efficiency of excitation energy to PSII reaction center in thylakoid was decreased with the decline of leaf phosphate level, and that the state transition was occurred during the induction of photosynthesis under these conditions.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.37-41
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• 2009

Previous studies have demonstrated that Shewanella decolorationis S12 can grow on the azo compound amaranth as the sole electron acceptor. Thus, to explore the mechanism of energy generation in this metabolism, membranous vesicles (MVs) were prepared and the mechanism of energy generation was investigated. The membrane, which was fragmentized during preparation, automatically formed vesicles ranging from 37.5-112.5 nm in diameter under electron micrograph observation. Energy was conserved when coupling the azoreduction by the MVs of an azo compound or Fe(III) as the sole electron acceptor with $H_2$, formate, or lactate as the electron donor. The amaranth reduction by the vesicles was found to be inhibited by specific respiratory inhibitors, including $Cu^{2+}$ ions, dicumarol, stigmatellin, and metyrapone, indicating that the azoreduction was indeed a respiration reaction. This finding was further confirmed by the fact that the ATP synthesis was repressed by the ATPase inhibitor N,N'-dicyclohexylcarbodiimide (DCCD). Therefore, this study offers solid evidence of a mechanism of microbial dissimilatory azoreduction on a subcell level.

• 분석과학
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• 제8권4호
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• pp.481-486
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• 1995

Quenching experiments by photoinduced electron transfer between a charged donor and a neutral acceptor were carried out in acetonitrile, dichloromethane and mixed solvents of acetonitrile and dichloromethane. Tris(2, 2'-bipyridine) ruthenium(II) ($[Ru(bpy)_3]^{2+}$) which has 2+ charge and dicyanobis (2, 2'-bipyridine) ruthenium(II) ($Ru(bpy)_2(CN)_2$) which has no charge were used as electron donors, and a series of tris(${\beta}$-diketonato) ruthenium (III) was used as acceptor. In dichloromethane, $[Ru(bpy)_3]^{2+}$ and its counter ions ($ClO{_4}^-$) form ion pair. In the estimate of ${\Delta}G$ of electron transfer, the electrostatic potential between counter ions and product ion pair produced by electron transfer must be taken into account. A similar effect of counter ions was found in mixed solvents of 10, 30, 50, 70 and 90% acetonitrile ratio in volume. The effect of counter ion on ${\Delta}G$ became smaller with the increase in acetonitrile ratio. The result in mixed solvents suggests that $[Ru(bpy)_3]^{2+}$ and its counter ions form ion pair even in 90% acetonitrile solution.

• 한국식품영양과학회지
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• 제41권10호
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• pp.1417-1422
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• 2012

Alkyl-glucoside의 생산을 위하여 상용화 cellulase인 Celluclast의 당전이 반응을 사용하였다. 5가지 종류의 알코올을 acceptor molecule로 하여 반응을 살펴본 결과 methyl alcohol, ethyl alcohol, isopropanol 그리고 butanol에서 당전이 반응이 일어남을 확인하였다. 반응 수율이 높았던, methyl alcohol과 ethyl alcohol의 반응산물을 MALDI-TOF MS와 효소적인 방법을 사용하여 각각의 산물이 methyl ${\beta}$-D-glucopyranoside와 ethyl ${\beta}$-D-glucopyranoside임을 확인하였다. 시간대별 methyl-glucoside와 ethyl-glucoside의 생산량을 비교하여 본 결과 9시간에서 최대 생산 수율 65% (mol/mol)와 59%(mol/mol)를 각각 보였으며, 이후 반응은 진행되지 않았다. Cellulose의 당전이 반응으로 생성된 부산물인 glucose를 제거하기 위하여 고정화 효모 system을 도입하였고, 그 결과 glucose를 모두 제거할 수 있었다. 이상의 결과에서 Celluclast를 이용한 alkyl-glucoside의 생산을 성공적으로 수행하였고, 고정화 효모 system을 도입하여 친환경적으로 부산물을 제거하여 고순도의 ethyl-glucoside를 생산하였다.

• 생명과학회지
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• 제21권11호
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• pp.1631-1635
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• 2011

재조합 아밀로수크라아제의 폴리페놀 배당체를 합성하는 능력을 검사하였다. 이 효소의 효소작용 특성에 근거하여 설탕을 기질로 사용하였으며 21 종류의 각기 다른 폴리페놀 화합물들이 수용체로 사용되었다. 당 전이 반응은 사용한 폴리페놀에 따라 하나 또는 두 개의 주요 폴리페놀 배당체를 합성하였다. 합성된 폴리페놀 배당체들은 박막 크로마토그래피법을 이용하여 확인되었고, 새로이 합성된 배당체의 구조는 당 전이 작용 특성에 근거하여 예측되었다. 수용체로 가능한 폴리페놀의 구조적 특징들이 평가되었으며, 이러한 결과는 Deinococcus geothermalis 유래 아밀로수크라아제가 식품, 화장품, 및 제약산업에서 높은 잠재성을 갖는 폴리페놀 배당체의 효소적 합성에 매우 효율적인 촉매로 활용될 수 있다는 것을 보여준다.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.465-469
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• 2013

Proton transfer reaction is one of the most fundamental processes in chemistry and life science. Excited state intramolecular proton transfer (ESIPT) has been studied as a model system of the proton transfer, since it can be conveniently initiated by light. We report ESIPT reaction dynamic of 1-hydroxy-anthraquione (1-HAQ) in solution by highly time-resolved fluorescence. ESIPT time of 1-HAQ is determined to be $45{\pm}10$ fs directly from decay of the reactant fluorescence and rise of the product fluorescence. High time resolution allows observation of the coherent vibrational wave packet motion in the excited state of the reaction product tautomer. The coherently excited vibrational mode involves large displacement of the atoms, which shortens the distance between the proton donor and the acceptor. With the theoretical analysis, we propose that the ESIPT of 1-HAQ proceeds barrierlessly with assistance of the skeletal vibration, which in turn becomes excited coherently by the ESIPT reaction.

• Journal of Photoscience
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• 제8권2호
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• pp.43-53
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• 2001

a, a parameter that describes how effectively photoinactivated PS II units protect their functional neighbours; car, carotenoids; ΔpH, transthylakoid pH difference; D1 protein, psbA gene product in the PS II reaction centre; f, functional fraction of PS II: F$\_$v//F$\_$m/, the ratio of variable to maximum chlorophyll a fluorescence; k$\_$d/, rate coefficient for degradation of D1 protein; k$\_$i/ and k$\_$r/, rate coefficient for photoinactivation and repair of PS II, respectively; NADP+, oxidized nicontinamide adenine dinucleotide phosphate; P680, the primary electron donor in the PSII reaction centre; Ph, pheophytin; PS, photosystem; Q$\_$A/, first quinone acceptor of an electron in PS II; R$\_$s/, the gross rate of D1 protein synthesis.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.128-131
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• 2017

We explore the inverse electron demand Diels-Alder reactions of tetrazines with various functional groups employing quantum calculations. In general, the rate of inverse electron demand Diels-Alder reaction depends on molecular orbital levels of electron donor and electron acceptor. Likewise, ${\pi}$ orbital of the dienophile and ${\pi}^*$ orbital of the diene is a key factor. In this work, we discuss the case where the energy of diene's ${\pi}^*$ molecular orbital is not the sole governing factor to determine the reaction rate, rather the rate shows strong correlation with the charge density of dienes.

• 한국미생물·생명공학회지
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• 제26권3호
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• pp.264-268
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• 1998

덱스트란수크라제는 Sucrose를 이용하여 덱스트란의 합성을 촉진하는데 sucrose이외에 다른 탄수화물이 효소 반응기 중에 존재하는 경우에는 Sucrose의 glucose를 이 탄수화물에 전달하는 반응을 촉진하여 새로운 구조의 산물을 생산한다. Leuconostoc mesenteroides B-742CB로 부터 얻은 덱스트란수크라제를 이용하여 플루란을 변형하고 그 조건을 최적화 하고자 했다. 수용성 변형 플루란은 이론적 수율의 57%(<$\pm$5)를 얻었다. 플루란 변형의 최적 조건으로는 pH 5.2, 28$^{\circ}C$ 에서 기질 0.37%(w/v)와 반응한 효소의 농도와 Sucrose농도가 각각 0.1 U/$m\ell$과 48mM일 때였다. 변형 플루란을 pullulanase, endodextranase로 처리하여 변형 전의 플루란과가수분해 상태를 비교 분석한 결과 변형전의 산물에 비해 이들 가수 분해 효소에 대해 더 저항성을 보였다. 변형 플루란을 methylation과 산가수분해 후 TLC한 결과 sucrose의 glucose가 플루란 glucose의 C3, C4, C6 위치의 free-OH group에 수식된 새로운 구조의 변형 플루란임을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3690-3694
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• 2013

The $H_2Ge=Ge:$ and its derivatives ($X_2Ge=Ge:$, X = H, Me, F, Cl, Br, Ph, Ar${\ldots}{\ldots}$) is a new species. Its cycloaddition reactions is a new area for the study of germylene chemistry. The mechanism of the cycloaddition reaction between singlet state Cl2Ge=Ge: and formaldehyde has been investigated with CCSD(T)//MP2/$6-31G^*$ method. From the potential energy profile, it could be predicted that the reaction has only one dominant reaction pathway. The reaction rule presented is that the two reactants first form a fourmembered Ge-heterocyclic ring germylene through the [2+2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge: atom in the four-membered Ge-heterocyclic ring germylene and the ${\pi}$ orbital of formaldehyde forming a ${\pi}{\rightarrow}p$ donor-acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge: atom in intermediate hybridizes to an $sp^3$ hybrid orbital after transition state, then, intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. The research result indicates the laws of cycloaddition reaction between $H_2Ge=Ge:$ and formaldehyde, and laid the theory foundation of the cycloaddition reaction between $H_2Ge=Ge:$ and its derivatives ($X_2Ge=Ge:$, X = H, Me, F, Cl, Br, Ph, Ar${\ldots}{\ldots}$) and asymmetric ${\pi}$-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds. The study extends research area and enriches the research content of germylene chemistry.