• Natural Product Sciences
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• 제16권1호
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• pp.6-9
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• 2010

In continuing our search for biologically active compounds from Korean Compositae medicinal plants, we investigated the constituents of the aerial parts of Lactuca indica L. and isolated a phenylpropanoid derivative from its MeOH extract. The chemical structure was characterized by spectroscopic methods, including 1D and 2D NMR to be di-E-caffeoyl-meso-tartaric acid (1). Compound 1 was isolated for the first time from this plant. In this paper, we suggest that the NMR assignment at C-2 of (+)-taraxafolin-B should be corrected. In the human HBV-transfected liver cell line HepG2.2.15, the compound 1 effectively reduced HBV DNA level in the release of mature HBV particles from HepG2.2.15 cultivation.

• Bulletin of the Korean Chemical Society
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• 제10권6호
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• pp.551-554
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• 1989

Quadrupole coupling constants of $^{63}$CU in the high $T_c$ superconductor $YBa_2Cu_3O_7_{-x}$, as determined by NQR or NMR studies, are compared with the values for representative Cu(Ⅱ) complexes determined by analyzing the forbidden lines in their EPR spectra. It is shown that the two NQR lines at 22 and 31 MHz correpsond to the quadrupole coupling constants of a square planar Cu(Ⅱ) complex and a square pyramidal Cu(Ⅱ) complex, respectively.t This result is in agreement with the assignment of these lines to Cu(1) and Cu(2) sites in YBCO based on the NMR spectra of oriented single crystals.

• Bulletin of the Korean Chemical Society
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• 제14권5호
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• pp.588-592
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• 1993

The $^1H-NMR$ signals of the heme methyl, propionate and related chemical groups of cytochrome $c_3$ from Desulfovibrio vulgaris Miyazaki F (D.v. MF) were site-specifically assigned by means of 1D-NOE, 2D-DQFCOSY and 2D-TOCSY spectra. They were consistent with the site-specific assignments of the hemes with the highest and second-lowest redox potentials reported by Fan et al. (Biochemistry, 29, 2257-2263 1990). The site-specific heme assignments were also supported by NOE between the methyl groups of these hemes and the side chain of Val-18.

• Natural Product Sciences
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• 제9권2호
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• pp.52-55
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• 2003

The aerial parts of Ephedra aphylla afforded two alkaloids belonging to two different classes. The first alkaloid, ephedradine C, belonging to the spermine alkaloid, a group characterized by its hypotensive effect. The other alkaloid, hordenine is a phenylalkylamine alkaloid isolated for the first time from Ephedra Species. The structures were elucidated by spectroscopic methods and the assignment of some carbons in ephedradine C was achieved based on 2 D-NMR experiments.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1996년도 정기총회 및 학술발표회
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• pp.18-18
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• 1996

Bacteriophage T4 endonuclease V initiates the repair of ultraviolet (UV)-induced pyrimidine dimer photoproducts in duplex DNA. The mechanism of DNA strand cleavage involves four sequential steps: linear diffusion along dsDNA, pyrimidine dimer-specific binding, pyrimidine dimer-DNA glycosylase activity, and AP lyase activity. (omitted)

• BMB Reports
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• 제36권5호
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• pp.505-507
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• 2003

One of the small proteins from Helicobacter pylori, acyl carrier protein (ACP), was investigated by NMR. ACP is related to various cellular processes, especially with the biosynthesis of fatty acid. The basic NMR resonance assignment is a prerequisite for the validation of a heterologuous protein interaction with ACP in H.pylori. Here, the results of the backbone $^1H$, $^{15}N$, and $^{l3}C$ resonance assignments of the H. pylori ACP are reported using double- and triple-resonance techniques. About 97% of all of the $^1HN$, $^{15}N$, $^{13}CO$, $^{13}C{\alpha}$, and $^{13}C{\beta}$ resonances that cover 76 of the 78 non-proline residues are clarified through sequential- and specific-assignments. In addition, four helical regions were clearly identified on the basis of the resonance assignments.

• 한국자기공명학회논문지
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• 제6권1호
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• pp.78-83
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• 2002

A new fluoroquinolone (DW-116) with a broad antibacterial spectrum was synthesized by introducing functional fluoropyridyl and methylpyrazine groups on N1, C7 position of quinolone moiety, respectively. $^{1}$H and $^{13}$ C NMR signal assignments and structure were completely elucidated by 2D-NMR methods. Physicochemical properties of products were also investigated. DW-116 is decomposed at 306.9$^{\circ}C$ and the decomposition starts at around 285$^{\circ}C$. The free base form is melt at 280.7$^{\circ}C$ and started to be decomposed immediately. DW-116 has two kinds of polymorphism which is important in drug action but these two plate and rod types have the same solubility in water. However the solubility is quite different in less or polar solvent. The plate type is more soluble in less polar solvent except in dichloromethane.

• 한국자기공명학회논문지
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• 제17권2호
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• pp.105-110
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• 2013

HP1492 is a NifU-like protein of Helicobacter pylori (H. pylori) and plays a role as a scaffold which transfer Fe-S cluster to Fe-S proteins like Ferredoxin. To understand how to bind to iron ion or iron-sulfur cluster, HP1492 was expressed and purified in Escherichia coli (E. coli). From the NMR measurement, we could carry out the sequence specific backbone resonance assignment of HP1492. Approximately 91% of all resonances could be assigned unambiguously. By analyzing results of CSI and TALOS from NMR data, we could predict the secondary structure of HP1492, which consists of three ${\alpha}$-helices and three ${\beta}$-sheets. This study is an essential step towards the structural characterization of HP1492.

• Archives of Pharmacal Research
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• 제20권6호
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• pp.633-636
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• 1997

In the course of searching for PAF receptor antagonists, pregomisin (1) and chamigrenal (2) were isolated from the fruits of Schizandra chinensis Baill by the bioactivity-guided isolation. Both compounds showed PAF antagonistic activity and the $IC_{50}$ values were $4.8{\times}10^{-5} M and 1.2{\times}10^{-4}M,$ respectively. In addition, the $^{13}C$ NMR assignments of 1 and 2 using DEPT, HMQC, COLOC and HMBC were reported for the first time.

• 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.