• 한국자기공명학회논문지
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• 제8권2호
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• pp.96-107
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• 2004

We prepared two oligonucleotides containing same base pairing, but different base sequence in the middle region, d(CGAATTCG) and d(CGTATACG). NMR and UV absorbance data represented that such variation in base sequence could cause a significant difference in melting temperature and dynamics between d(CGAATTCG)$_2$ and d(CGTATACG)$_2$ duplexes, which are regarded to be associated with the stacked structure and the width of the minor groove of them. The latter showed poor stability compared to the former, because of poor stacking of bases. And berenil could bind to the minor groove of d(CGAATTCG)$_2$ which is relatively narrow, more strongly than d(CGTATACG)$_2$ and this gave rise to large improvement in thermal stability of the d(CGAATTCG)$_2$ duplex, compared to d(CGTATACG)$_2$.

• Bulletin of the Korean Chemical Society
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• 제7권2호
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• pp.89-96
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• 1986

The NMR chemical shift arising from 4d electron angular momentum and 4d electron spin dipolar-nuclear spin angular momentum interaction for a $4d^1$ system in a strong crystal field of octahedral symmetry, when the threefold axis is chosen as the quantization axis, has been investigated. A general expression using a nonmultipole expansion method is derived for the NMR chemical shift. From this expression all the multipolar terms are determined. We find that the nonmultipolar results for the NMR chemical shift ${\Delta}B$, is exactly in agreement with the multipolar results when $R {\ge} 0.20$ nm. It is also found that the 1/$R^7$ term contributes to the NMR chemical shift almost the same as the 1/$R^5$ in magnitude. The temperature dependence analysis of ${\Delta}B$/B(ppm) at various values of R shows that the 1/$T^2$ term has the dominant contribution to the NMR chemical shift but the contributions of other two terms are certainly significant for a $4d^1$ system in a strong crystal field of octahedral symmetry when the threefold axis is chosen to be the axis of quantization.

• Applied Biological Chemistry
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• 제38권2호
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• pp.184-189
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• 1995

인삼의 다이올계 조사포닌 분획으로 부터 및 단계의 화학반응을 이용하여 (20S)-ginsenoside $Rh_2$ 및 그 입체이성체인 (20R)-ginsenoside $Rh_2$를 제조하였다. 또한 DEPT, $^1H-^1H$ COSY, HMQC, HMBC 및 NOESY와 같은 NMR 기법을 이용하여 두 화합물의 $^1H-NMR$과 $^{13}C-NMR$의 signal들을 완전히 동정하였다.

• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.961-965
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• 1997

1H NMR spectra of 3,3-dimethylpiperidine (1) at -70 to 30 ℃ exhibit gradual change from slow to rapid exchange between two alternate chair forms. The exchange rate constant was determined as a function of temperature by simulating the line shape of the signal from the two methyl groups using the modified Bloch equations. The resulting free energy of activation is ΔG* = 44.4±1.9 kJ mol-1 at 298 K. The 1H NMR spectrum of a D2O or dimethylsulfoxide-d6 (DMSO-d6) solution containing 1 and [SiW11CoⅡO39]6- exhibits separate signals for the free ligand and the complex, indicating that the ligand exchange is slow on the NMR time scale. In D2O the piperidine ring is frozen as a chair form even at room temperature with the cobalt ion bonded to the axial position of the nitrogen atom. When DMSO-d6 is added to the D2O solution, the NMR spectral change suggests that a rapid exchange occurs between the chair form and another conformer. It is proposed that the conformation of ^b1^b coordinated to [SiW11CoⅡO39]6- in DMSO-d6 is close to a twist form.

• 한국자기공명학회논문지
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• 제25권2호
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• pp.12-16
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• 2021

Daphnia magna is used as target organism for environmental metabolomics. The metabolome of D. magna was studied with NMR spectroscopy. Most studies used the extract of D. magna, but the reproducibility cannot be obtained using extracted sample. In this study, lyophilized D. magna samples were analyzed with two different ¹H NMR techniques, HR-MAS on intact tissues and solution NMR on extracted tissues. Samples were measured three times using 600 MHz NMR spectrometer. Metabolite extraction required more than twice as many D. magna, but the metabolite intensity was lower in solution NMR. In the spectra of HR-MAS NMR, the lipid signal was observed, but they did not interfere with metabolite profiling. We also confirmed the effect of swelling time on signal intensities of metabolites in HR-MAS NMR, and the results suggest that appropriate swelling should be used in lyophilized D. magna to improve the accuracy of metabolite profiles.

• 한국자기공명학회논문지
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• 제8권2호
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• pp.115-126
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• 2004

Four secondary metabolites from an unidentified tunicate were isolated by treatment with trichloroethyl chloroformate(TECF) or acetic anhydride in pyridine. Their structures were determined by an extensive NMR analysis and the configuration of diacetyl derivatives(3a, 4a) was assigned by comparing with NMR data of a similar compound. Three new naturally occurring compounds (1, 3, 4) showed potent brine shrimp lethality and antifungal effect against Candia albicans.

• Bulletin of the Korean Chemical Society
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• 제30권1호
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• pp.149-152
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• 2009

Hydrotalcites are anionic clays that are quite prevalent in nature and their importance is growing more and more because of their very wide range of potential applications and uses. Understanding the structural and compositional changes that occur on the molecular scale during the thermal decomposition of hydrotalcite compounds is essential for the basic prediction and comprehensive understanding of the behavior and technical application of these materials. In this study, several hydrotalcite compounds calcined at different temperatures for applications in a chlorine resistant textile were prepared and 27-Aluminm solid-state nuclear magnetic resonance (NMR) spectroscopy was used as a tool to study their local structure and behavior. The changes in the Al coordination of the hydrotalcite compounds were investigated with one dimensional (1D) solid-state magic angle spinning (MAS) NMR spectroscopy. The two broad resonances arising from the structurally different Al coordinations of these compounds were clearly resolved by two dimensional (2D) triple quantum magic angle spinning (3QMAS) NMR spectroscopy.

• Journal of the Korean Wood Science and Technology
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• 제37권1호
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• pp.114-120
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• 2009

현사시나무 수피를 채취하여 기건 시킨 후 70% 아세톤 용액으로 추출하고 농축한 후 헥산, 디클로로메탄, 에틸아세테이트 및 수용성으로 순차 추출하여 동결건조하였다. 에틸아세테이트 분획에 대하여 Sephadex LH-20 컬럼크로마토그래피와 분취 TLC를 반복적으로 수행하여 화합물을 분리하였다. 화합물의 구조는 산 가수분해와 $^1H$-NMR, $^{13}C$-NMR, 2D-NMR 및 MALDI TOF-MS 스펙트럼을 분석하여, grandidentatin A(cis-2-hydroxycyclohexyl 6-O-p-coumaroyl-${\beta}$-D-glucopyranoside)로 동정하였다. Grandidentatin A는 현사시나무 수피에서 처음 분리되었으며, 문헌에 보고되지 않은 신규화합물이다.

• 분석과학
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• 제7권2호
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• pp.213-224
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• 1994

선택적으로 중수소를 치환시킨 싸이클로옥타논의 여러 동위원소 이성질체들을 합성하였다. 고유동위원소 효과에 의해 영향을 받는 $^{13}C$ NMR 화학적 이동값들을 각 이성질체에 대해 저온에서 계통적으로 관찰하였다. 특히 싸이클로옥타논이 선호하는 안정한 형태 이성질체인 클 boat-chair 형과 연관시켜 이 효과들을 논의하였다.

• 약학회지
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• 제40권4호
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• pp.422-427
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• 1996

The anti-Ex-A IgG was specifically labeled with stable isotopes, DL-His-2,4-$d_2$, L-Phe-$d_5$, L-Trp-$d_5$, L-Tyr-2,6-$d_2$ and L-[1-$^{13}C$]Trp, by growing hybridoma cell in serum-free medium. By use of NMR spectroscopy with selectively labeled Fab fragment, we applied a paratope mapping on antigen-antibody complex. Assignments of the observed carbonyl carbon resonances have been determined by using $^{13}C$-$^{15}N$ double labeling method in order to assign the Trp resonances. Photo CIDNP was also applied to investigate the antigen-binding site(s) on the surface residues of antibody. We found that Trp 36, which is located at the $V_H$ domain, is an important residue to bind to Ex-A, however, two Tyr on the surface of anti-Ex-A IgG plays no crucial role to bind to antigen. On the basis of these results, we demonstrate that stable isotope-aided NMR strategy can be extended to molecular structural analyses of the complex of an Fab fragment and a protein antigen.