• Journal of Ginseng Research
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• 제38권2호
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• pp.116-122
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• 2014

Ginseng roots were extracted with aqueous methanol, and extracts were suspended in water and extracted successively with ethyl acetate and n-butanol. Column chromatography using the n-butanol fraction yielded four purified triol ginseng saponins: the ginsenosides Re, Rf, Rg2, and 20-gluco-Rf. The physicochemical, spectroscopic, and chromatographic characteristics of the ginsenosides were measured and compared with reports from the literature. For spectroscopic analysis, two-dimensional nuclear magnetic resonance (NMR) methods such as $^1H$-$^1H$ correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond connectivity were employed to identify exact peak assignments. Some peak assignments for previously published $^1H$-and $^{13}C$-NMR spectra were found to be inaccurate. This study reports the complete NMR assignment of 20-gluco-Rf for the first time.

• 분석과학
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• 제12권3호
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• pp.184-189
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• 1999

수용액에서 vanadate와 N-benzyliminodiacetate (Bz-IDA) 리간드의 상호작용을 $^{51}V$ 핵자기공명분광법과 순환전압-전류법을 이용하여 조사하였다. $^{51}V$ 핵자기공명분광법 결과 바나듐(V)-Bz-IDA착물생성에 의한 두 개의 특정 피크(-515.5 ppm 및 -500.1 ppm)를 관찰할 수 있었다. 순환전압-전류법을 이용하여 얻어진 결과 바나듐(V)-Bz-IDA착물의 산화-환원파의 전위값은 각각 -0.05 V 및 -0.13 V에서 관찰하였다. 이로써 산화-환원반응은 가역적 일전자반응으로 추정되었다.

• Bulletin of the Korean Chemical Society
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• 제7권5호
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• pp.334-337
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• 1986

The preparation of the metal-metal bonded complex $Cp_2ZrClFeCp(CO)_2$ has been achieved by the reaction of $Cp_2ZrCl_2$ and strong nucleophile $NaFeCp(CO)_2$. The more soluble metal-metal bonded complexes $Cp_2ZrRFeCp(CO)_2(R=CH_3,\;n-C_8H_{17}$) have also been prepared through the reaction of Cp$_{2}$ZrRCl and NaCpFe(CO)$_{2}$. The complexes were characterized by IR, Raman, $^{1}$H NMR and Mass spectra. The complete absorption (100-3800 cm$^{-1}$) spectra for the three metal-metal bonded molecules are reported and the bands of each vibration were assigned.

• 한국식품영양과학회지
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• 제45권11호
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• pp.1580-1588
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• 2016

잔대의 70% 에탄올 추출물은 강한 항산화 효과 및 산화적 스트레스 조건에서 뇌신경세포 사멸 억제 효과가 있었다. 6개의 분획물 중에 잔대 추출물의 클로로포름 분획물(AT-CH)은 높은 DPPH 라디칼 소거작용 및 세포 내 활성산소종(ROS) 소거작용을 가지고 있었고 $H_2O_2$에 대항하여 뇌신경 세포(SK-N-SH) 보호 효과가 가장 뛰어났다. 활성이 가장 우수한 클로로포름 분획물을 대상으로 주요 물질을 순수분리한 후 $^1H-NMR$, $^{13}C-NMR$ 그리고 EI mass spectra를 이용하여 화학구조를 분석한 결과 phytosterols(${\beta}$-sitosterol과 daucosterol)이라는 것을 알 수 있었다. ${\beta}$-Sitosterol과 daucosterol 역시 산화적 스트레스에 대항하여 SK-N-SH 세포를 보호하는 작용이 있었다. AT-CH 그리고 이것으로부터 분리된 화합물은 p38 경로를 저해하였다. 이들 결과는 AT-CH는 p38 경로를 저해하고 세포 내 ROS 소거작용에 의해 산화적 스트레스로부터 뇌신경세포 보호 효과를 가질 것이라 제안하였다.

• 한국자기공명학회논문지
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• 제14권2호
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• pp.127-133
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• 2010

Redox-dependent conformational change of human 8-kDa Dynein light chain (LC8) plays important role in regulating NF-${\kappa}B$ signaling pathway. In this study we characterized the structural states of the oxidized and reduced forms of LC8 by using NMR spectroscopy. The $^1H-^{15}N$ 2D HSQC spectra of oxidized LC8 indicated that no significant change in tertiary structure of LC8 occurred upon oxidation. The chemical shift perturbations of LC8 upon oxidation suggest a redox-dependent quaternary structural change.

• 한국자기공명학회논문지
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• 제14권2호
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• pp.117-126
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• 2010

Hsp33 is a molecular chaperone achieving a holdase activity upon response to a dual stress by heat and oxidation. Despite several crystal structures available, the activation process is not clearly understood, because the structure inactive Hsp33 as its reduced, zinc-bound, monomeric form has not been solved yet. Thus, we initiated structural investigation of the reduced Hsp33 monomer by NMR. In this study, to overcome the high molecular weight (33 kDa), the protein was triply isotope-[$^{13}C$, $^{15}N$, $^2H$]-labeled and its inactive, monomeric state was ensured. 2D-[$^1H$, $^{15}N$]-TROSY and a series of triple resonance spectra could be successfully obtained on a high-field (900 MHz) NMR machine with a cryoprobe. However, under all of the different conditions tested, the number of resonances observed was significantly less than that expected from the amino acid sequence. Thus, a possible contribution of dynamic conformational exchange leading to a line broadening is suggested that might be important for activation process of Hsp33.

• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.2959-2962
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• 2013

As the concentration of aqueous $CD_3OH$ solutions was decreased, the OD peaks in $^2H$ NMR spectra grew relative to the $CD_3$ peaks. Isotope impurity for OH groups of $CD_3OH$ and deuterium naturally present in water contributed to the OD peaks. Using these peak area data, the site-specific isotope populations of isotope enriched chemicals were measured. In addition, the method using both $^1H$ and $^2H$ NMR spectroscopy was demonstrated with neat $CD_3OH$ to measure the site-specific isotope populations. The results indicate that although it represents only ~0.015% of hydrogen isotopes, the deuterium naturally present in solvents cannot be ignored, especially when the concentration of deuterium-enriched solutes is varied. Proton/deuteron exchange between methyl and methyl/hydroxyl groups was confirmed to be negligible, while that among hydroxyl groups was detectable.

• 한국자기공명학회논문지
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• 제11권2호
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• pp.85-94
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• 2007

Vanilloid receptor I [transient receptor potential vanilloid subfamily member 1 (TRPV1), also known as VR1] is a non-selective cationic channel activated by noxious heat, vanilloids, and acid, thereby causing pain. VR1 possesses six transmembrane domain and N-and C-terminus cytosolic domains, and appears to be a homotetramer. We studied the structural properties of Cterminus of VR1 (VR1C) using CD and NMR spectroscopy. DPC micelles, with a zwitterionic surface, and SDS micelles, with a negatively charged surface, were used as a membrane mimetic model system. Both SDS and DPC micelles could increase the stability of helical structures and/or reduce the aggregation form of the VR1C. However, the structural changing mode of the VR1C induced by the SDS and DPC micelles was different. The changes according to the various pHs were also different in two micelles conditions. Because the net charges of the SDS and DPC micelles are negative and neutral, respectively, we anticipate that this difference might affect the structure of the VR1C by electrostatic interaction between the surface of the VR1C and phospholipids of the detergent micelles. Based on these similarity and dissimilarity of changing aspects of the VR1C, it is supposed that the VR1C probably has the real pI value near the pH 7. Generally, mild extracellular acidic pH ($6.5{\sim}6.8$) potentiates VRI channel activation by noxious heat and vanilloids, whereas acidic conditions directly activate the channel. The channel activation of the VRI might be related to the structural change of VR1C caused by pH (electrostatic interactions), especially near the pH 7. By measuring the $^1-^{15}N$ TROSY spectra of the VR1C, we could get more resolved and dispersed spectra at the low pH and/or detergent micelles conditions. We will try to do further NMR experiments in low pH with micelles conditions in order to get more information about the structure of VR1C.

• 미생물학회지
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• 제50권4호
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• pp.381-383
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• 2014

미생물 기원의 ${\alpha}$-glucosidase 저해제를 탐색하는 과정에서 토양에서 분리한 균주인 Bacillus sp. SKU31-1 배양액에서 강력한 저해제 compound K을 일련의 크로마토그래피 방법에 의해 분리 정제하였고 $^1H$ NMR, $^{13}C$ NMR, $^1H-^1H$ COSY spectra 분석과 문헌조사를 통해 5-amino-1-hydroxymethyl-1,2,3,4-cyclohexanetetrol로 동정되었다. Compound K의 ${\alpha}$-glucosidase 저해 활성은 $IC_{50}$값이 maltose 기질에서는 $1.9{\mu}M$이고, sucrose 기질 사용시 4.9 mM이었다. Lineweaver Burk plot에 의해 $K_i$값이 0.15 mM 로 강력한 경쟁적 저해제 임이 밝혀졌다.

• 한국초전도저온공학회지:초전도와저온공학
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• 제20권2호
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• pp.15-22
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• 2018

The present article briefly overviews the plan for a new project on joint technology for HTS wires/cables and describes the development plan for the world's highest field NMR magnet, which is a major development item in the project. For full-fledged social implementation of superconducting devices, high temperature superconducting (HTS) wire is a key technology since they can be cooled by liquid nitrogen and they can generate a super-high magnetic field of >>24 T at liquid helium temperatures. However, one of the major drawbacks of the HTS wires is their availability only in short lengths of a single piece of wire. This necessitates a number of joints being installed in superconducting devices, resulting in a difficult manufacturing process and a large joint resistance. In Japan, a large-scale project has commenced, including two technical demonstration items: (i) Development of superconducting joints between HTS wires, which are used in the world's highest field 1.3 GHz (30.5 T) NMR magnet in persistent current mode; the joints performance is evaluated based on NMR spectra for proteins. (ii) Development of ultra-low resistive joints between DC superconducting feeder cables for railway systems. The project starts a new initiative of next generation super-high field NMR development as well as that of realization of better superconducting power cables.