• Journal of the Korean Magnetic Resonance Society
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• v.25 no.1
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• pp.1-7
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• 2021

Employing of 13C stable-isotopes in NMR metabolomics can give unique splitting patterns and coupling constants information originated from 13C-13C coupling interaction that provide an important structural information regarding the cellular metabolic process. But it has been known that an undesirable signal distortion in 2D heteronuclear correlation study, due to 13C-13C interaction, hampers an analysis of the coupling information. Recently, we proposed J-scaled distortion-free heteronuclear single-quantum coherence (HSQC) sequence which provides a distortion-free 13C-13C coupling information with a selective resolution enhancement of JCC splitting. In this paper, we dicuss theoretical aspect and practical feature of J-scaled HSQC pulse sequence. The conceptual explanation of orgin of the signal distortion by 13C-13C coupling interaction and design of J-scaled HSQC through exemplified results are provided in brief.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.4
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• pp.131-134
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• 2017

Proton detected Heteronuclear Multiple Quantum Coherence (HMQC) and Heteronuclear Single Quantum Coherence (HSQC) essentially provide the same information - correlation of the chemical shift of the proton to J-coupled hetero nuclei such as $^{13}C$ or $^{15}N$ nuclei. This paper is a practical note for the students who ask which one is better and which methods they use routinely. Artifact suppression using phase cycling and gradient pulses are discussed.

• Journal of the Korean Magnetic Resonance Society
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• v.27 no.2
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• pp.10-15
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• 2023

The Strain-Promoted Azide-Alkyne Cycloaddition (SPAAC) is a powerful method for synthesizing triazoles, even under physiological conditions, without a copper catalyst. This technique provides an efficient means for everyone to synthesize complex triazole derivatives rapidly. In order to investigate the configuration of triazole derivatives using bicyclo[6.1.0.]-nonyne (BCN) and chiral azide, it is necessary to employ the 2D NMR. Both 1D and 2D NMR (COSY, HSQC, ¹⁵N HMBC) are used to analyze the complex triazole product containing cyclooctyne, a diastereomeric product. The stereometric difference of the proton bonded to the same carbon is determined through the HSQC assignment. The intriguing splitting pattern of carbon resonances also reveals their diastereomeric configuration and will aid in further research based on physiological knowledge.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.125-131
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• 2018

Chemical shift perturbation (CSP) is a simple NMR technique for studying binding of a protein to various ligands. CSP is the only technique that can directly provide both a value for the dissociation constant and a binding site from the same set of measurements. To accurately analyze the CSP data, the exact binding mode such as multiple binding, should be carefully considered. In this review, we analyzed systematically the CSP data with multiple modes. This analysis might provide insight into the mechanism on how proteins selectively recognize their target ligands to achieve the biological function.

• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.356-360
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• 2007

5,7-Diaryl-3,4,6-trihydronaphthalen-2-ones have been synthesized from 3,5-diaryl-cyclohex-2-en-1- ones and methyl vinyl ketone in the presence of sodium ethoxide. The products were characterized by IR, UV-Visible, 1H-NMR, 13C-NMR and mass spectral techniques. To confirm 1H and 13C signals, HSQC spectrum was recorded and analyzed.

• Journal of the Korean Magnetic Resonance Society
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• v.1 no.2
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• pp.103-111
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• 1997

Proper pulse sequences and experimental optimization for the 3D 15N edited TOCSY and NOESY spectra were described. Using sensitivity enhancement approach with coherent selection by pulsed field gradients described by Kay and co-workers, an considerable gain in sensitivity was achieved. The sensitivity was also improved by minimal water saturation using water flip-back pulse. Among the three types of TOCSY mixing pulse, named MLEV-17, DIPSI-2rc, DIPSI-2rc sequence gave the most sensitive spectrum. These results suggest an appropriate pulse sequence for for those 3D experiments for large proteins.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.144-148
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• 2018

Catalytic enzyme Pyrazinamidase (PncA) from Mycobacterium tuberculosis can hydrolyze substrate pyrazinamide (PZA) to pyrazoic acid (POA) as active form of compound. Using NMR spectroscopy, pH-dependent catalytic properties were monitored including metal binding mode during converting PZA to POA. There seems to be a conformational change through zinc binding in active site from the perturbation of peak intensities in series of 2D HSQC spectra the conformation changes through zinc binding.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.80-80
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• 1995

T4 Endonuclease V (Mw 16,000) acts as a repair enzyme for UV induced pyrimidine dimers in DNA. Many researchers have studied the biochemical characteristics of the enzyme. However the precise action mechanism of T4 endo V has not fully elucidated yet. In our laboratory NMR spectroscopy technique is being used for the structural study of T4 endo V. Because of its low temperature stability and high content of ${\alpha}$-helix, the conventional $^1$H NMR technique was inapplicable. Therefore we utilized stable isotope labeling technique and so far prepared about 10 amino acid specific labeled proteins. The HSQC spectra of amino acid specific labeled proteins will help us to interpret the triple resonance 3D, 4D data which are under processing, We also studied the behaviors of specific amino acid residues whose roles might be critical. When the enzyme labeled by $\^$15/N-Thr was mixed with the substrate oligonucleotide (semispecific -TT- sequence), one crosspeak in its HSQC spectrum was completely desappeared, which means that one of seven Thr residues is in the binding site of the enzyme with DNA, This result is well consistent with previous report that implicated the Thr 2 residue in the activity of the enzyme. Similar studies were carried on the behaviors of Arg and Tyr residues.

• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.520-525
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• 2007

Three-component coupling of thiourea/urea, various structurally diverse aromatic aldehydes and ammonium acetate is catalyzed by activated fly ash in dry media under microwave irradiation to give 6-aryl-1,2,4,5-tetrazinan- 3-thiones/ones in good yields. The structure of 6-aryl-1,2,4,5-tetrazinan-3-thiones/ones have been elucidated on the basis of their melting points, elemental analysis, MS, IR, 1H NMR, D2O exchange, 13C NMR and two dimensional NMR spectral studies including Homonuclear Correlation (HOMOCOR) and Heteronuclear Single Quantum Correlation (HSQC) spectra.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.930-936
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• 2011

Two new cyclic depsipeptides wewakamide A (1) and guineamide G (2) have been isolated from the marine cyanobacterium Lyngbya semiplena and Lyngbya majuscula, respectively, collected from Papua New Guinea. The amino and hydroxy acid partial structures of wewakamide A and guineamide G were elucidated through extensive spectroscopic techniques, including HR-FABMS, 1D $^1H$ and $^{13}C$ NMR, as well as 2D COSY, HSQC, HSQC-TOCSY, and HMBC spectra. The sequence of the residues of wewakamide A was determined through a combination of ESI-MS/MS, HMBC, and ROESY. Wewakamide A possesses a ${\beta}$-amino acid, 3-amino-2-methylbutanoic acid (Maba) residue, which has only been previously identified in two natural products, guineamide B (3) and dolastatin D (4). Although both new compounds (1,2) showed potent brine shrimp toxicity, only guineamide G displayed significant cytotoxicity to a mouse neuroblastoma cell line with $LC_{50}$ values of 2.7 ${\mu}M$.