• Title/Summary/Keyword: }NMR$

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$^1/H-NMR$ and NOE Studies of 2-Cephems and 3-Cephems

  • Im, Chae-Uk;Yim, Chul-Bu;Micetich, Ronald-G.;Mohsen, Daneshtalab
    • Archives of Pharmacal Research
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    • v.20 no.6
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    • pp.652-655
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    • 1997
  • $^{1}H-NMR$ signals of 2-cephems and 3-cephems have been assigned and the Nuclear Overhauser Effect (NOE) study of these compounds was undertaken.

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Determination of Isoprenyl and Lavandulyl Positions of Flavonoids from Sophora flavescens by NMR Experiment

  • Ryu, Shi-Yong;Lee, Hyun-Sun;Kim, Young-Kyoon;Kim, Sung-Hoon
    • Archives of Pharmacal Research
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    • v.20 no.5
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    • pp.491-495
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    • 1997
  • All fifteen flavonoids (1-15) have been isolated from the roots of Sophora flavescens (Leguminosae) as active principles of the cytotoxic property toward human tumor cell lines such as A549, SK-OV-3, SK-Mel-2, XF498 and HCT15, in vitro. By means of spectral analyses, particularlyby the aid of various two dimensional NMR experiments, all $^1H-NMR$ ad $^{13}C$ -NMR signals of 1-15 were completely assigned, and thus the structures of 1-15 were established unambiguously.

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Construction of 1H-15N Double Resonance Solid-State NMR Probe for Membrane Proteins in Aligned Bicelles

  • Park, Tae-Joon;Kim, Ji-Sun;Um, Seung-Hoon;Kim, Yong-Ae
    • Bulletin of the Korean Chemical Society
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    • v.31 no.5
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    • pp.1187-1191
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    • 2010
  • $^1H-^{15}N$ heteronuclear dipolar coupling solid-state NMR experiments on lipid bilayer or bicelle samples are very useful for the structural studies of membrane proteins. However, to study these biological samples using solid-state NMR, a specific probe with high efficiency and high capability is required. In this paper, we describe the optimized design, construction, and efficiency of a 400 MHz wide-bore $^1H-^{15}N$ solid-state NMR probe with 5-mm solenoidal rf coil for high power, multi-pulse sequence experiments, such as 2D PISEMA or 2D SAMMY.

NMR Studies of Metal-binding Luteinizing Hormone Releasing Hormone

  • Won, Ho-Shik
    • Bulletin of the Korean Chemical Society
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    • v.32 no.11
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    • pp.4021-4026
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    • 2011
  • Functions of the luteinizing hormone releasing hormone (LHRH) and its induced release by divalent metal ions have received great attention because this neurotransmitter subsequently regulates the secretion of luteinizing hormone (LH). Metal-LHRH complexes were synthesized by addition of various Cu(II),Ni(II),Zn(II) ions into LHRH in order to understand how the induced release of LHRH is possible. The degree of complexation was monitored by $^1H$, $^{13}C$-NMR chemical shifts, and final products were identified by Mass spectrometry. Solutionstate structure determination of Zn(II)-LHRH out of metal-complexes was accomplished by using NMR and NMR-based distance geometry (DG). Interproton distance information from nuclear Overhauser effect spectroscopy was utilized for structure determination. Structure obtained in this study has a cyclic conformation exhibiting a specific ${\alpha}$-helical turn with residue numbers His[2]-Leu[7] out of 10 amino acids. Comparison of chemical shifts and EPR studies of Ni(II),Cu(II)-LHRH complexes exhibit that these metal complexes have 4-coordination geometry.

Characterization of Metakaolinite with Multiple Quantum MAS NMR

  • Han, Oc-Hee;Stefan Steuernagel
    • Journal of the Korean Magnetic Resonance Society
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    • v.4 no.1
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    • pp.12-18
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    • 2000
  • Metakaolinite produced by thermal transformation from kaolinite was studied by 27Al multiple quantum magic angel spinning (MQMAS) NMR technique in addition to 1-dimensional 27Al and 29Si MAS NMR. Our results confirm that 4-, 5-, 6- coordinated aluminum sites co-exit with some distribution of isotropic chemical shifts. This is consistent with amorphous character of metakaolinite observed with X-ray diffraction. In addition, characterization with MQMAS is briefly discussed in comparison with other NMR techniques to identify different aluminum sites especially when peaks are severely overlapped in 1-dimensional 27Al MAS NMR spectra.

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A Comparison of Three Dimensional Structures of Biosynthesized Preproinsulin and Insulin Using NMR

  • Oh, Mi-Na;Mok, K.-Hun;Lim, Yoong-Ho
    • Applied Biological Chemistry
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    • v.41 no.8
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    • pp.572-577
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    • 1998
  • The solution conformation of the human insulin precursor, preproinsulin, is described in terms of NMR spectral data. NMR experiments were performed on preproinsulin, whose structure was compared with the NMR structure of native human insulin. Despite the presence of the C-peptide and/or the signal peptide, secondary structure analyses indicate that the native structures of the A and B chains are well conserved even in preproinsulin. The observed relative robustness of the native structure in precursor forms permits further protein engineering experiments where the C-peptide or N-terminal signal sequence can be altered for the purpose of increasing expression or purification yields when producing recombinant human insulin.

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Structural Studies of Hydrotalcite Compounds Calcined with Different Temperatures by $^{27}Al$ Solid-state NMR Spectroscopy

  • Park, Tae-Joon;Kim, Yong-Ae
    • Journal of the Korean Magnetic Resonance Society
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    • v.11 no.1
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    • pp.42-47
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    • 2007
  • Several hydrotalcite compounds calcined with different temperature for applications in a chlorine resistant textile were prepared, and its structural changes in dependence on the temperature were studied by using $^{27}Al$ solid-state nuclear magnetic resonance(NMR) spectroscopy. We found that the Al coordination was partly lowered from octahedral to tetrahedral site as the calcined temperature goes up. And we also investigated the hydrotalcite-treated textile for chlorine resistance by using $^{27}Al$ solid-state NMR spectroscopy.

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Revision of $^{13}C$ NMR Assignments of ${\beta}-Sitosterol$ and ${\beta}-Sitosteryl-3-O-{\beta}-D-glucopyranoside$ Isolated from Plantago asiatica Seed (질경이씨로 부터 분리한 ${\beta}-Sitosteryl-3-O-{\beta}-D-glucopyranoside$${\beta}-Sitosterol$$^{13}C$ NMR)

  • Chang, Il-Moo;YunChoi, Hye-Sook;Yamasaki, Kazuo
    • Korean Journal of Pharmacognosy
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    • v.12 no.1
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    • pp.12-14
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    • 1981
  • ${\beta}-Sitosteryl-3-O-{\beta}-D-glucopyranoside$ was isolated from the seeds of Plantago asiatica (Plantaginaceae). The assignments of $^{13}C$ NMR spectra of ${\beta}-sitosterol$ and ${\beta}-sitosteryl-3-O-{\beta}-D-glucopyranoside$ were made by comparing with $^{13}C$ NMR spectra of cholesterol and $cholesteryl-3-O-{\beta}-D-glucopyranoside$. Our data indicate that the revision of previous $^{13}C$ NMR spectral assignment is needed.

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Synthesis and Analysis of 6,6-dichlorobicyclo[3, 1, 0]hexane-3-carboxylic acid (6,6-Dichlorobicyclo[3, 1, 0]hexane-3-carboxylic acid의 합성과 분석)

  • Lee, Kwang-Soo;Yang, Jae-Kun
    • Analytical Science and Technology
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    • v.14 no.1
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    • pp.1-7
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    • 2001
  • 6,6-Dichlorobicyclo[3, 1, 0]hexane-3carboxylic acid was synthesized by dichlorocarbene addition into 3-cyclopentenecarboxylic acid using BTEA.Cl as phase transfer catalyst. $^1H$ NMR $^{13}C$ NMR data analyst showed that this compound had boat-like conformation and carboxyl group existed as trans form.

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Applications of NMR spectroscopy based metabolomics: a review

  • Yoon, Dahye;Lee, Minji;Kim, Siwon;Kim, Suhkmann
    • Journal of the Korean Magnetic Resonance Society
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    • v.17 no.1
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    • pp.1-10
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    • 2013
  • Metabolomics is the study which detects the changes of metabolites level. Metabolomics is a terminal view of the biological system. The end products of the metabolism, metabolites, reflect the responses to external environment. Therefore metabolomics gives the additional information about understanding the metabolic pathways. These metabolites can be used as biomarkers that indicate the disease or external stresses such as exposure to toxicant. Many kinds of biological samples are used in metabolomics, for example, cell, tissue, and bio fluids. NMR spectroscopy is one of the tools of metabolomics. NMR data are analyzed by multivariate statistical analysis and target profiling technique. Recently, NMR-based metabolomics is a growing field in various studies such as disease diagnosis, forensic science, and toxicity assessment.