• Journal of the Korean Chemical Society
• /
• v.50 no.3
• /
• pp.183-189
• /
• 2006

A series of substituted styryl 4-methoxy-1-naphthyl ketones [(2E)-1-(4-methoxy-1-naphthyl)-3-phenyl-2-propen-1-ones] were synthesized using facile method of microwave assisted condensation reaction. The yield of chalcones is more than 90%. They are characterized by their physical constants, micro analysis, infrared (KBr, 4000-400 cm？1) and NMR both 1H and 13C spectral data. From infrared spectra, the s-cis and s-trans stretching vibrations of carbonyl group, from NMR spectra the ethylenic proton and carbon chemical shifts (ppm) are assigned. These spectral data are correlated with various Hammett substituent constants. From the results of statistical analysis the effect of substituents on CO, ？ and ？ proton and carbons are explained.

• Korean Journal of Food Science and Technology
• /
• v.35 no.4
• /
• pp.653-659
• /
• 2003

A 20 MHz pulsed NMR systems was employed to discriminate the geographical origin of soybeans and black beans (yak-kong) from Korea and foreign countries. Crude fat contents measured by soxhlet method were significantly (p<0.05) different between domestic and imported soybeans. Moisture and crude protein contents, measured by AOAC, were significantly different between domestic and imported black beans. In soybeans, values by solid fat content method and Carr-Purcell-Meiboom-Gill (CPMG) method using 20 MHz pulsed NMR showed the significant difference among soybeans from various the geographical origins. In black beans (yak-kong), NMR values measured by NMR except $T_1$ SR pulse sequence revealed the significant difference by the geographical origins. The habitat of soybeans and black beans could be identified by canonical discriminant analysis of chemical composition with $70{\sim}91.7\;%$ accuracy. Low field NMR data followed by discriminant analysis, however, granted the 100% of accuracy for classification of soybeans.

• Analytical Science and Technology
• /
• v.17 no.2
• /
• pp.98-107
• /
• 2004

In this study, $^1H$ NMR spectroscopy and HPLC were used to identify the type and quantity of each component in an acrylic coating materials applied for an automotive part. By the $^1H$ NMR analysis, it was found that this acrylic coating contained about 88.40 wt% of poly methyl methacrylate (PMMA), 7.05 wt% of methyl methacrylate (MMA), and 2.36 wt% of allyl methacrylate. Polymer additives such as a benzotriazole light stabilizer (Hisorb 328), an oxanilide light stabilizer, butylated hydroxy toluene (BHT), and dimethyl phthalate (DMP) were also identified and measured quantitatively from the $^1H$ NMR spectra. However, only two light stabilizers were identified by reverse phase (RP) HPLC analysis using Bondapak C18 column, methanol mobile phase, and a PDA (Photodiode array) detector. The contents of two light stabilizers in the acrylic coating were measured by a quantitative analysis through UV-Vis spectroscopy and compared with the NMR data. The analytical informations from $^1H$ NMR spetra were better than those from HPLC-PDA plot.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.7
• /
• pp.1944-1950
• /
• 2014

Employment of a time consuming, sophisticated calculation using the all-atom force field and generalized-Born implicit solvent model (GBIS) for refinement of NMR structures has become practical through advances in computational methods and capacities. GBIS refinement improves the qualities of the resulting NMR structures with reduced computational times. However, the contribution of GBIS to NMR structures has not been sufficiently studied in a quantitative way. In this paper, we report the effects of GBIS on the refined NMR structures of ubiquitin (UBQ) and GB1 with subsets of distance restraints derived from experimental data. Random omission prepared a series of distance restraints 0.05, 0.1, 0.3, 0.5, and 0.7 times smaller. For each number, we produced five different restraints for statistical analysis. We then recalculated the NMR structures using CYANA software, followed by GBIS refinements using the AMBER package. GBIS improved both the precision and accuracy of all the structures, but to varied levels. The degrees of improvement were significant when the input restraints were insufficient. In particular, GBIS enabled GB1 to form an accurate structure even with distance restraints of 5%, revealing that the root-mean-square deviation was less than 1 ${\AA}$ from the X-ray backbone structure. We also showed that the efficiency of searching the conformational space was more important for finding accurate structures with the calculation of UBQ with 5% distance restraints than the number of conformations generated. Our data will provide a meaningful guideline to judge and compare the structural improvements by GBIS.

• Journal of the Korean Chemical Society
• /
• v.55 no.4
• /
• pp.590-593
• /
• 2011

A novel organotin(IV) complex has been prepared from $Bu_2SnCl_2$ and the N, O and S donor ligand, 5-(p-dimethylaminobenzylidene) rodanine (HL). The ligand is deprotonated in the presence of a base and the complex with the general formula $SnBuCl_2L$ is formed. This complex was fully characterized by IR, $^1H$ NMR and $^{119}Sn$ NMR and elemental analysis. Spectroscopic data indicate the ligand is coordinated through the oxygen atom to the tin and the coordination number of four is supported by $^{119}Sn$ NMR data in solution.

• Proceedings of the Korean Magnetic Resonance Society Conference
• /
• 2002.08a
• /
• pp.90-90
• /
• 2002

Syndecans, transmembrane heparan sulfate proteoglycans, are coreceptors with integrin in cell adhesion process. It forms a ternary signaling complex with protein kinase C and phosphatidylinositol 4,5 bisphosphate (PIP2) for integrin signaling. NMR data indicates that cytoplasmic domain of syndecan-4 (4L) undergoes a conformational transition in the presence of PIP2, forming oligomeric conformation. The structure based on NMR data demonstrated that syndecan-4L itself forms a compact intertwined symmetric dimer with an unusual clamp shape for residues Leu$^{186}$ -Ala$^{195}$ . The molecular surface of the syndecan-4L dimer is highly positively charged. In addition, no inter-subunit NOEs in membrane proximal amino acid resides (Cl region) has been observed, demonstrating that the Cl region is mostly unstructured in syndecan-4L dimmer. However, the complex structure in the presence of PIP2 induced a high order multimeric conformation in solution. In addition, phosphorylation of cytoplasmic domain induces conformational change of syndecan-4, resulting inhibition of PKC signaling. The NMR structural data strongly suggest that PIP2 promotes oligomerization of syndecan-4 cytoplasmic domain for PKC activation and further induces structural reorganization of syndecan for mediating signaling network in cell adhesion procedure.

• Polymer(Korea)
• /
• v.39 no.2
• /
• pp.287-292
• /
• 2015

Characterization of a series of bio-based terpolymers containing various amounts of ethylene glycol, 1,4-cyclohexylene dimethanol, and isosorbide units were studied by $^1H$ NMR and $^{13}C$ NMR. The NMR results revealed that they had all random microstructures and that their sequence distribution was affected by the content of isosorbide. From DSC data for the terpolymer series investigated, it was observed that the glass transition temperature increased mainly as the content of isosorbide increased. The glass transition temperatures of terpolymers were estimated from the composition by extended Fox equation.

• Journal of the Korean Magnetic Resonance Society
• /
• v.26 no.1
• /
• pp.1-9
• /
• 2022

There are two distinct approaches to improving the quality of protein NMR structures during refinement: all-atom force fields and accumulated knowledge-assisted methods that include Rosetta. Mao et al. reported that, for 40 proteins, Rosetta increased the accuracies of their NMR-determined structures with respect to the X-ray crystal structures (Mao et al., J. Am. Chem. Soc. 136, 1893 (2014)). In this study, we calculated 32 structures of those studied by Mao et al. using all-atom force field and implicit solvent model, and we compared the results with those obtained from Rosetta. For a single protein, using only the experimental NOE-derived distances and backbone torsion angle restraints, 20 of the lowest energy structures were extracted as an ensemble from 100 generated structures. Restrained simulated annealing by molecular dynamics simulation searched conformational spaces with a total time step of 1-ns. The use of GPU-accelerated AMBER code allowed the calculations to be completed in hours using a single GPU computer-even for proteins larger than 20 kDa. Remarkably, statistical analyses indicated that the structures determined in this way showed overall higher accuracies to their X-ray structures compared to those refined by Rosetta (p-value < 0.01). Our data demonstrate the capability of sophisticated atomistic force fields in refining NMR structures, particularly when they are coupled with the latest GPU-based calculations. The straightforwardness of the protocol allows its use to be extended to all NMR structures.

• Journal of the Korean Magnetic Resonance Society
• /
• v.3 no.1
• /
• pp.52-59
• /
• 1999

Authors synthesized common intermediates which are applicable for potential antibiotics. Their complete 13C and 1H NMR chemical shift data as well as carbon-and proton-fluorine coupling constants are reported. The knowledge of proton and carbon-fluorine coupling constants may help one assign the NMR data of the fluorinated quinolone derivatives. These results agree with the data published previously.

• Journal of the Korean Magnetic Resonance Society
• /
• v.4 no.2
• /
• pp.116-124
• /
• 2000

Singular value decomposition (SVD) has been used during past few decades in the advanced NMR data processing and in many applicable areas. A new modified SVD, piecewise polynomial truncated SVD (PPTSVD) was developed far the large solvent peak suppression and noise elimination in U signal processing. PPTSVD consists of two algorithms of truncated SVD (TSVD) and L$_1$ problems. In TSVD, some unwanted large solvent peaks and noises are suppressed with a certain son threshold value while signal and noise in raw data are resolved and eliminated out in L$_1$ problem routine. The advantage of the current PPTSVD method compared to many SVD methods is to give the better S/N ratio in spectrum, and less time consuming job that can be applicable to multidimensional NMR data processing.