• 대한화학회지
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• 제51권6호
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• pp.520-525
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• 2007

Thiourea/urea, 다양한 aromatic aldehydes, ammonium acetate의 세가지 요소를 가지고 마이크로파의 조 사하에서 무수조건의 활성화된 비산화재를 촉매로 사용하여 높은 수율의 6-aryl-1,2,4,5-tetrazinan-3-thiones/ones를 얻었 다. 6-aryl-1,2,4,5-tetrazinan-3-thiones/ones의 구조는 녹는점, MS, IR, 1H NMR, D2O 교환, 13C NMR, 이차원의 NMR 스펙트럼(HOMOCOR, HSQC)을 바탕으로 증명되었다.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.649-653
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• 1995

Solution-state structure of native F430 was determined by using NMR methods and NMR-based distance geometry (DG) computations. Structures were generated with loose NOE-derived interproton distance restraints (2.0-2.5 Å, 2.0-3.5 Å and 2.0-4.5 Å for strong, medium, and weak NOE cross-peak intensities, respectively). 2D NOESY back-calculations of structures were subsequently carried out for establishing the consistence between experimental data and DG-model structures. The back-calculated 2D NOESY spectra of resulting DG structures were well consistent with experimental 2D NOESY spectra. Superposition of 20 independent structures with macrocyclic ring atoms and all atoms of F430 afforded pairwise root mean square deviations (RMSD) of 0.025-0.125 Å and 0.64-1.3 Å, respectively. The macrocyclic rings of structures are well converged to a unique conformation with saddle-shaped deformation whereas most of side chains are not converged. The average dihedral angle (N1-N2-N3-N4, 27.78±1.50°) of 20 DG-structures exhibits that the macrocyclic ring conformation is puckered as much as 12,13-diepimeric F430 (28.75±4.07°).

• Bulletin of the Korean Chemical Society
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• 제7권3호
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• pp.170-178
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• 1986

The NMR chemical shift arising from 4d electron angular momentum and 4d electron angular momentum and 4d electron spin dipolar-nuclear spin angular momentum interactions for a $4d^1$ system in a strong crystal field environment of trigonal symmetry, when the threefold axis is chosen to be the axis of quantization axis, has been examined. A general expression using the nonmultipole expansion method (exact method) is derived for the NMR chemical shift. From this expression all the multipolar terms are determined. We observe that along the (100), (010), (110), and (111) axes the NMR chemical shifts are positive while along the (001) axis, it is negative. We observe that the dipolar term (1/R3) is the dominant contribution to the NMR chemical shift except for along the (111) axis. A comparison of the multipolar terms with the exact values shows also that the multipolar results are exactly in agreement with the exact values around $R{\geqslant}0.2$ nm. The temperature dependence analysis on the NMR chemical shifts may imply that along the (111) axis the contribution to the NMR chemical shift is dominantly pseudo contact interaction. Separation of the contributions of the Fermi and the pseudo contact interactions would correctly imply that the dipolar interaction is the dominant contribution to the NMR chemical shifts along the (100), (010), (001), and (110) axes, but along the (111) axis the Fermi contact interaction is incorrectly the dominant contribution to the NMR chemical shift.

• Bulletin of the Korean Chemical Society
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• 제18권10호
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• pp.1090-1093
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• 1997

The solvent effects on the isotropic NMR shifts in conformationally rigid ligands such as quinuclidine, pyridine, and 4-aminopyridine coordinated to the paramagnetic polyoxometalate, [SiW11CoⅡO39]6- (SiW11Co), are reported. For these complexes the ligand exchange is slow on the NMR time scale and pure 1H NMR signals have been observed at room temperature. The signals for the SiW11Co complexes are shifted upfield whe dimethyl sulfoxide-d6 (DMSO) is added to a D2O solution. The isotropic shifts are separated into contact and pseudocontact contributions by assuming that the contact shifts are proportional to the isotropic shifts of the same ligands coordinated to [SiW11NiⅡO39]6-. It is shown that both the contact and pseudocontact shifts decrease (the absolute values of the pseudocontact shifts increase), when D2O is replaced by DMSO. It is suggested that D2O, a strong hydrogen bond donor, withdraws electron density from [SiW11CoⅡO39]6-, increasing the acidity of the cobalt ion toward the axial ligand. When D2O is replaced by DMSO, the acidity of the cobalt ion in SiW11Co decreases, weakening the Co-N bond. Then both the contact and pseudocontact shifts are expected to decrease in agreement with the observed solvent effects.

• Journal of the Korean Wood Science and Technology
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• 제41권6호
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• pp.566-575
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• 2013

주목열매에서 분리한 과육과 씨를 95% EtOH 용액을 사용하여 각각 1.15 kg과 0.94 kg을 유리 용기에 침지하여 추출하고, 농축된 추출용액을 용매의 극성에 따라 n-hexane, dichloromethane, ethyl acetate 및 수용성으로 순차 분획한 후, 동결건조하였다. 혼합물로부터 순수한 화합물을 분리하기 위하여 ethyl acetate 및 수용성 분획에 대하여 Sephadex-LH 20 칼럼크로마토그래피를 실시하였다. 단리된 화합물들의 구조는 flavan 화합물의 경우 $^1H$-NMR, $^{13}C$-NMR 및 EI-MS 스펙트럼을 측정하였으며, 탄수화물은 보다 정확한 구조를 결정하기 위해 COSY, HSQC와 같은 2-D NMR과 LC/MS 스펙트럼을 이용하여 구조를 결정하였다. 또한 구성당 분석을 위해 acid hydrolysis, permethylation을 실시하여 구성당의 성분과 결합위치를 확인하였다. 위의 실험을 통하여 (+)-catechin (1), (-)-epicatechin (2), (+)-gallocatechin (3), (-)-epigallocatechin(4) 및 ${\beta}$-D-fructofuranose-($2{\rightarrow}4$)-O-${\beta}$-D-glucopyranose($1{\rightarrow}4$)-O-${\alpha}$-D-glucopyranose-($1{\rightarrow}2$)-O-${\beta}$-D-fructofuranose (5)의 구조를 결정하였다.

• 약학회지
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• 제39권3호
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• pp.268-275
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• 1995

A novel polyacetylene was isolated from Cirsium spp., as well as five known ones, and its chemical structure was determined as heptadeca-1-en-11.13-diyne-8R, 9S, 10R-triol(1) on the basis of spectral data and chemical reactions. $^{1}$H-and $^{13}$C-NMR data of these polyacetylenes were completely assigned by the appfication of 2D-NMR techniques.

• 한국축산식품학회지
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• 제39권1호
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• pp.1-12
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• 2019

The objective of this study was to establish an optimized 1D $^1H$ quantitative nuclear magnetic resonance (qNMR) analytical method for analyzing polar metabolites in meat. Three extraction solutions [0.6 M perchloric acid, 10 mM phosphate buffer, water/methanol (1:1)], three reconstitution buffers [20 mM 3-morpholinopropane-1-sulfonic acid, 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid, phosphate buffer], and two pulse programs (zg30, noesypr1d) were evaluated. Extraction with 0.6 M perchloric acid and 20 mM phosphate resulted in a stable baseline and no additional overlap for quantifying polar metabolites in chicken breast. In qNMR analysis, zg30 pulse program (without water-suppression) showed smaller relative standard deviation (RSD) and faster running time than noesypr1d (water-suppression). High-performance liquid chromatography was compared with qNMR analyses to validate accuracy. The zg30 pulse program showed good accuracy and lower RSD. The optimized qNMR method was able to apply for beef and pork samples. Thus, an optimized 1D $^1H$ qNMR method for meat metabolomics was established.

• 한국자기공명학회논문지
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• 제17권1호
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• pp.59-66
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• 2013

BldD, a developmental transcription factor from Streptomyces coelicolor, is a homodimeric, DNA-binding protein with 167 amino acids in each subunit. Each monomer consists of two structurally distinct domains, the N-terminal domain (BldD-NTD) responsible for DNA-binding and dimerization and the C-terminal domain (BldD-CTD). In contrast to the BldD-NTD, of which crystal structure has been solved, the BldD-CTD has been characterized neither in structure nor in function. Thus, in terms of structural genomics, structural study of the BldD-CTD has been conducted in solution, and in the present work, mainchain NMR assignments of the recombinant BldD-CTD (residues 80-167 of BldD) could be achieved by a series of heteronuclear multidimensional NMR experiments on a [$^{13}C/^{15}N$]-enriched protein sample. Finally, the secondary structure prediction by CSI and TALOS+ analysis using the assigned chemical shifts data identified a ${\beta}-{\alpha}-{\alpha}-{\beta}-{\alpha}-{\alpha}-{\alpha}$ topology of the domain. The results will provide the most fundamental data for more detailed approach to the atomic structure of the BldD-CTD, which would be essential for entire understanding of the molecular function of BldD.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.263-263
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• 1994

Annexin I is a member of the in family of calcium dependent phospholipid banding proteins and is an in vitro phospholipase $A_2$ (PLA$_2$) inhibitor. The mechanism of PLA$_2$ inhibition by annexin I is still ambiguous. The structure of annexin I was studied at the atomic level by using nuclear magnetic resonance (NMR), circular dichrotsm (CD) and fluorescence spectroscopy. Recombinant human annexin I and N-terminally truncated annexin I (1-31 deleted: d-annexin I) were purified and their NMR spectra were compared. The NMR spectra of the two were similar. When $Ca^{2+}$ ion added to annexin I ad d-annexin I, peak broadening occurred, but no significant spectroscopic change was observed. When porcine pancreatic PLA$_2$ was added to deuterium labeled annexin I, an interaction of annexin I with PLA$_2$ was observed as indicated by the disappearance and shift of several peaks in the NMR spectrum. This result supports a protein-protein interaction mechanism for PLA$_2$ inhibition by annexin I.I.

• 한국자기공명학회논문지
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• 제3권1호
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• pp.12-26
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• 1999

The 1H NMR signals of the heme methyl, propionate and related chemical groups of cytochrome C3 from Desulfovibrio vulgaris Miyazaki F (D.v. MF) were assigned by means of 1D NOE, 2D DQFCOSY and 2D TOCSY spectra. They were consistent with the assignments of the hemes with the highest and second-lowest redox potentials reported by Gayda et al. [Reference: 15]. The heme assignments were also supported by NOE between the methyl groups of these hemes and the side chain of Val-18, All the results contradicted the heme assignments for D.v. MF cytochrome C3 made on the basis of NMR [Reference: 11]. Based on these assignments, the interaction of cytochrome C3 with ferredoxin I was investigated by NMR. The major interaction site of cytochrome C3 was identified as the heme with the highest redox potential, which is surrounded by the highest density of positive charges. The stoichiometry and association constant were two cytochrome C3 molecules per monomer of ferredoxin I and 108 M-2 (at 53 mM ionic strength and $25^{\circ}C$), respectively.