• Bulletin of the Korean Chemical Society
• /
• v.34 no.10
• /
• pp.2959-2962
• /
• 2013

As the concentration of aqueous $CD_3OH$ solutions was decreased, the OD peaks in $^2H$ NMR spectra grew relative to the $CD_3$ peaks. Isotope impurity for OH groups of $CD_3OH$ and deuterium naturally present in water contributed to the OD peaks. Using these peak area data, the site-specific isotope populations of isotope enriched chemicals were measured. In addition, the method using both $^1H$ and $^2H$ NMR spectroscopy was demonstrated with neat $CD_3OH$ to measure the site-specific isotope populations. The results indicate that although it represents only ~0.015% of hydrogen isotopes, the deuterium naturally present in solvents cannot be ignored, especially when the concentration of deuterium-enriched solutes is varied. Proton/deuteron exchange between methyl and methyl/hydroxyl groups was confirmed to be negligible, while that among hydroxyl groups was detectable.

• Journal of Plant Biotechnology
• /
• v.34 no.3
• /
• pp.207-212
• /
• 2007

This study describes a simple and rapid method for quantitative determination of $\gamma$-aminobutyric acid (GABA) using $^1H$ NMR spectroscopy from whole cell extracts of plant suspension cultures. When 9 cell lines derived from 8 species of higher plants maintained in liquid Marashige and Skoog (MS) medium supplemented with 1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) were subjected to $^1H$ NMR, a cell line of Coriandrum sativum L. exhibited the highest level of GABA. The level reached up to 16.9 mg/dry wt when cells were cultured in MS medium supplemented with 0.5 mg/L 2,4-D after 3 weeks of incubation. The method for quantitative determination of GABA using $^1H$ NMR established in this study could be applied to high-throughput screening of various plant resources for GABA production and the cell suspension culture system of C. sativum could be further developed for commercial production of GABA.

• Journal of the Korean Magnetic Resonance Society
• /
• v.11 no.2
• /
• pp.73-84
• /
• 2007

MTH1821 (UniProtKB/TrEMBL ID O27849) is a 96-residue hypothetical protein from the open reading frame of Methanobacterium thermoautotrophicum H one of the target organisms of structural genomics pilot project. Proteins which contain conserved sequence compared with MTH1821 have not been discovered yet and the functional and structural information for MTH1821 is not available. Here, we present the sequence-specific backbone resonance using multidimensional heteronuc1ear NMR spectroscopy and propose the secondary structure using GetSBY software. The backbone resonances of N, HN, $C_{\alpha}$, $C_{\beta}$, CO and $H_{\alpha}$ which are necessary for a prediction of secondary structure by GetSBY were assigned about 98% (557/568). The secondary structure of MTH1821 confirmed that it is comprised of four strand regions and two helical regions. This report will provide a valuable resource for the calculation solution structure of MTH1821 and for the other hypothetical protein that is targeted for structural-based functional discovery.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.6
• /
• pp.829-832
• /
• 2004

The pure product of 2,3-diaminophenazine was prepared by the enzyme-catalyzed reaction of ophenylenediamine-$H_2O_2$-horseradish peroxidase and characterized by UV/Vis spectroscopy, IR spectroscopy and NMR spectroscopy. The electrochemical behaviour of 2,3-diaminophenazine on the glassy carbon electrode was studied. The interaction between 2,3-diaminophenazine and deoxyribonucleic acid was studied by cyclic voltammetry method and UV/Vis spectroscopy, which indicated that the interaction between them is intercalation. The influence of reacting time was also studied. The binding ratio of the 2,3-diaminophenazine-DNA complex is calculated to be 1 : 2 and the binding constant is to be $5.07{\times} 10^3L{\cdot}mol^{-1}$ at room temperature.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.11
• /
• pp.2651-2654
• /
• 2009

In borohydride-protected nanosilvers in laponite sol, the silver particles aggregate to form short chains and a dumbbell shape. The $^{1}H$ NMR measurements in this study represent, to our knowledge, the first observation of proton resonances of borohydride-protected nanosilvers in aqueous solution. Borohydride on nanosilver can be exchanged with 11-mercaptoundecanoic acid (MUA) or trioctylphosphine (TOP). Transmission electron microscopy and UV-Vis spectroscopy data show that the number of aggregated silver nanoparticles decreases upon addition of aforementioned ligands due to the formation of silver MPCs (monolayer-protected clusters). Adsorption of MUA or TOP on nanosilver is confirmed through the observation of broad proton resonances of MPCs in $^{1}H$ NMR spectra.

• Natural Product Sciences
• /
• v.22 no.1
• /
• pp.30-34
• /
• 2016

A simple and rapid method based on proton nuclear magnetic resonance spectroscopy was developed for determination of trans-anethole content in fennel essential oil. Spectra of pure trans-anethole, of the pure essential oil of fennel, and of the pure oil of fennel with thymol internal standard were recorded. The signal of $H-1^/$ was used for quantification of trans-anethole. This proton signal is well separated in the proton magnetic resonance spectrum of the compound. No reference compound is needed and cheap internal standard was used. The results obtained from spectroscopic analysis were compared with those obtained by gas chromatography. Additionally, the developed method was used for determination of the type of vegetable oil used as a carrier in commercial products, which cannot be quantified as such by gas chromatography. This study demonstrates the application of proton nuclear magnetic resonance spectroscopy as a quality control method for estimation of essential oil components.

• YAKHAK HOEJI
• /
• v.38 no.3
• /
• pp.300-310
• /
• 1994

Physicochemical properties for the inclusion complex of chenodeoxycholic acid(CDCA) and it's $7{\beta}-hydroxy$ epimer ursodeoxycholic acid(UDCA) with ${\beta}-cyclodextrin({\beta}-CyD)$ were studied. The formation of the complex in the solid state were confimed by polarized microscopy and differential scanning calorimetry(DSC). Proton nuclear magnetic resonance$(^1H-NMR)$spectroscopy showed that CDCA and UDCA form an inclusion complex with ${\beta}-CyD$ in aqueous solution. The 1 : 1 stoichiometry of the complex was dextermined by the continuous variation method. From DSC and $^1H-NMR$ studies, there were not any differences between CDCA and UDCA. Complex of CDCA and UDCA showed increase in solubility and dissolution compared with CDCA and UDCA alone, respectively. Solubility pattern of UDCA complex was pH independent but, CDCA complex was like that of CDCA. Dissolution rate increased markedly in case of UDCA complex compared with CDCA complex, especially in acidic pH value.

• Journal of radiological science and technology
• /
• v.44 no.4
• /
• pp.335-342
• /
• 2021

Studies on the side effects of contrast agents are being discussed based on various cases, but studies analyzing the chemical structure of the underlying contrast agents are difficult to understand as the manufacturers have not disclosed them. Therefore, in this study, the chemical structure of the contrast medium was analyzed using ¹H-NMR spectrometer for Omnipaque contrast medium prepared from Iohexol, which is a nonionic iodide contrast medium, Xenetix contrast medium from Iobitridol, and Iomeron contrast medium from Iomeprol. As a result, it was found that the Omnipaque contrast medium of Iohexol had 6 carboxyl groups, 3 carbonyl groups, 4 amine groups, 1 methyl group, and 2 cyano groups. It was found that the Xenetix contrast medium of the iobitridol formulation had 6 carboxyl groups, 3 carbonyl groups, 2 amine groups, and 4 cyano groups. It was found that the Iomeron contrast agent of the Iomeprol formulation had 5 carboxyl groups, 3 carbonyl groups, 4 amine groups, 1 methyl group, and 2 cyano groups. As shown in this study, the chemical structure of the non-ionic monomer contrast agent increases its affinity with water by binding a number of hydroxyl groups (OH) to the carboxyl group. It is necessary to accurately identify each of these factors and analyze the physical and chemical changes of the contrast medium according to various environmental factors.

• Bulletin of the Korean Chemical Society
• /
• v.16 no.9
• /
• pp.864-869
• /
• 1995

Investigation of the structures of the gangliosides has proven to be very important in the understanding of their biological roles such as regulation of differentiation and growth of cells. We used nuclear magnetic resonance spectros-copy in order to investigate the structure of GA1. In order to do this, the assignment of spectra is a prerequisite. Since GA1 does not have polar sialic acid, the spectral overlap is severe. In order to solve this problem, we use 2D NMR spectroscopy and heteronuclear 1H/13C correlated spectroscopy in this study. Here, we report the complete assignment of the proton and the carbon spectra of the GA1 in DMSO-d6-D20 (98:2, v/v). These assignments will be useful for interpreting 1H and 13C NMR data from uncharacterized oligosaccharides and for determining the linkage position, the number of sugar rings, and the sequence of new ganglioside. Amide proton in ring Ⅲ shows many interring nOes and has intramolecular hydrogen bonding. This appears to be an important factor in tertiary folding of GA1. Based on this assignment, determination of three dimensional structure of GA1 will be carried out. Studies on the conformational properties of GA1 may lead to a better understanding of the molecular basis of its functions.

• Macromolecular Research
• /
• v.13 no.6
• /
• pp.467-476
• /
• 2005

The main objective of this study was to develop and characterize pH-sensitive biodegradable polymeric materials. For pH-sensitivity, we employed three kinds of moieties: 2-amino-3-(lH-imidazol-4-yl)-propionic acid (H), N-[4-( 4,6-dimethyl-pyrimidin-2ylsulfamoyl)-phenyl]succinamic acid (SM), and 2- {3-[ 4-( 4,6-dimethyl-pyrim­idin- 2-ylsulfamoyl)-phenylcarbamoyl]-propionylamino} -3-(3 H - imidazol-4-yl)-propionic acid (SH). The pH -sensitive diblock copolymers were synthesized by ring opening polymerization and coupling reaction from poly(ethylene glycol) (MPEG), $\varepsilon$-caprolactone (CL), D,L-lactide (LA) and pH-sensitive moieties. The pH-sensitive SH molecule was synthesized in a two-step reaction. The first step involved the synthesis of SHM, a methyl ester derivative of SH, by coupling reaction of SM and L-histidine methyl ester dihydrochloride, whereas the second step involved the hydrolysis of the same. The synthesized SM, SHM and SH molecules were characterized by FTIR, $^{1}H$-NMR and $^{13}C$-NMR spectroscopy, whereas diblock copolymers and pH-sensitive diblock copolymer were characterized by $^{1}H$-NMR and GPC analysis. The critical micelle concentrations were determined at various pH conditions by fluorescence technique using pyrene as a probe. The micellization and demicellization studies of pH-sensitive diblock copolymers were also done at different pH conditions. The pH-sensitivity was further established by acid-based titration and DLS analysis.