• 한국자기공명학회논문지
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• 제27권4호
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• pp.35-41
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• 2023

From a marine sponge Dysidea species, four new furanosesquiterterpenoids were isolated and characterized. Their structural elucidation was achieved through an extensive analysis employing NMR, MS data, and DFT method. Notably, all compounds shared as identical molecular formula. Compound 2 was identified as a derivative of compound 1, while compounds 3 and 4 exhibited an identical planar structure. Determination of the configurations of chiral centers in compounds 1 and 2 involved a comparative analysis between measured and calculated ECD spectra, along with the application of DP4+ probability analysis. Distinctly, the configurations of isomers 3 and 4 were established by scrutinizing proton chemical shifts based on the NOE correlation.

• 분석과학
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• 제11권4호
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• pp.292-296
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• 1998

헤테로 고리 화합물인 isoquinoline과 외부치환체로서 $COOCH_3$, CN 및 $CH_3$ 작용기들이 치환된 화합물들의 혼합물을 정상 및 역상법으로 분리 한 결과, 이동상의 종류에 따라 용리순서에 용매화 효과가 나타났다. 또한, 헤테로 고리 화합물 내부의 방향족성이 없는 2-methylindoline과 방향족성이 있는 2-methylindole, 그리고 헤테로 원자가 질소와 산소인 benzoxazole과 질소와 황인 benzothiazole의 머무름거동은 정상 액체 크로마토그래피의 경우 시료 분자와 충진제의 흡착 표면과의 흡착력으로 설명할 수 있었고, 역상 액체 크로마토그래피의 경우는 시료와 정지상과의 소수성 상호작용 등으로 설명할 수 있었다.

• 대한화학회지
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• 제18권3호
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• pp.215-220
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• 1974

저자들은 tetrahedrane생성의 전구체인 t-butenedial bistosylhydrazone의 입체적인 구조를 연구할 목적으로 이의 유사한 구조인 ${\alpha},{\beta}$위치에 이중결합을 가지고 있는 몇 가지 phenylhydrazone을 합성하고 이들의 형태 및 배위를 nmr spectra의 해석으로부터 구명했다. 벤젠용매와 aliphatic solvent(CC14, DMSO)에서의 chemical shift의 차이로 부터 이들 물질이 syn-configuration을 가지고 있음을 알았으며 spin-spin coupling constant 로부터 이들 물질의 형태를 고찰하였다.

• Bulletin of the Korean Chemical Society
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• 제29권10호
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• pp.1920-1926
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• 2008

We investigated the C-H bond activation mechanism of aldimine by the [RhCl$(PPH_3)_3$] model catalyst using DFT B3LYP//SBKJC/6-31G*/6-31G on GAMESS. Due to their potential utility in organic synthesis, C-H bond activation is one of the most active research fields in organic and organometallic chemistry. C-H bond activation by a transition metal catalyst can be classified into two types of mechanisms: direct C-H bond cleavage by the metal catalyst or a multi-step mechanism via a tetrahedral transition state. There are three structural isomers of [RhCl$(PH_3)_2$] coordinated aldimine that differ in the position of chloride with respect to the molecular plane. By comparing activation energies of the overall reaction pathways that the three isomeric structures follow in each mechanism, we found that the C-H bond activation of aldimine by the [RhCl$(PH_3)_3$] catalyst occurs through the tetrahedral intermediate.

• BMB Reports
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• 제36권2호
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• pp.167-172
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• 2003

The kinetics of thermal inactivation of copper-containing amine oxidase from lentil seedlings were studied in a 100 mM potassium phosphate buffer, pH 7, using putrescine as the substrate. The temperature range was between $47-60^{\circ}C$. The thermal inactivation curves were not linear at 52 and $57^{\circ}C$; three linear phases were shown. The first phase gave some information about the number of dimeric forms of the enzyme that were induced by the higher temperatures using the "conformational lock" pertaining theory to oligomeric enzyme. The "conformational lock" caused two additional dimeric forms of the enzyme when the temperature increased to $57^{\circ}C$. The second and third phases were interpreted according to a dissociative thermal inactivation model. These phases showed that lentil amine oxidase was reversibly-dissociated before the irreversible thermal inactivation. Although lentil amine oxidase is not a thermostable enzyme, its dimeric structure can form "conformational lock," conferring a structural tolerance to the enzyme against heat stress.

• Mass Spectrometry Letters
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• 제6권3호
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• pp.53-58
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• 2015

Recombinant erythropoietins (EPOs) are an important class of biotherapeutics that stimulate red blood cell production. The quality, safety, and potency of EPO variants are determined largely by their glycosylation, which makes up nearly half their mass. Thus, detailed glycomic analyses are important to assess biotherapeutic quality and establish the equivalency of biosimilar EPOs now coming to market. High-resolution mass spectrometry (MS) has recently emerged as the premier tool for glycan analysis in EPOs. Using the accurate mass measurements provided by high-resolution MS, the compositions of even large, complex glycans can easily be determined. When combined with a nano-LC separation, differentiation of structural isomers also becomes a possibility. These components, together, provide a comprehensive picture of biotherapeutic glycosylation. In this review, we provide an overview of MS-based analytical platform for glycomic characterization of EPO biotherapeutics and biosimilars.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.368-372
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• 2009

The trace polymer and additives in used stripper solutions were analyzed by a combination of Py-GC/MS and ESI-MS. In the comparison of the pyrolysates produced by the pyrolysis of the pure stripper and photoresist at $500{^{\circ}C}$, the presence of novolac polymer in the used stripper was confirmed by the presence of the characteristic peaks of its pyrolysates, such as those of the methylphenol, di-methylphenol and methylenebis(methylphenol) isomers. The intact trace polymer was measured by ESI-MS, which showed the distribution of oligomers at intervals of 120 Da, indicating di-methylphenol to be the repeat unit. Additional MS/MS measurements demonstrated that the end group is methylphenol and the repeat groups are di-methylphenol. Some modified oligomers caused by the methylation or di-methylation of the repeat unit were also identified. Although the polymer is only present at a trace level in the used stripper, these combined analytical methods provided the means to qualify the stripper solution through the identification and structural determination of the polymer.

• Biomolecules & Therapeutics
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• 제31권1호
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• pp.108-115
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• 2023

Numerous psychotropic and addictive substances possess structural features similar to those of β-phenethylamine (β-PEA). In this study, we selected 29 β-PEA derivatives and determined their structure-activity relationship (SAR) to their ability to inhibit dopamine (DA) reuptake; conducted docking simulation for two selected compounds; and identified their potential functionals. The compounds were subdivided into arylethylamines, 2-(alkyl amino)-1-arylalkan-1-one derivatives and alkyl 2-phenyl-2-(piperidin-2-yl)acetate derivatives. An aromatic group, alkyl group, and alkylamine derivative were attached to the arylethylamine and 2-(alkyl amino)-1-arylalkan-1-one derivatives. The inhibitory effect of the compounds on dopamine reuptake increased in the order of the compounds substituted with phenyl, thiophenyl, and substituted phenyl groups in the aromatic position; compounds with longer alkyl groups and smaller ring-sized compounds at the alkylamine position showed stronger inhibitory activities. Docking simulation conducted for two compounds, 9 and 28, showed that the (S)-form of compound 9 was more stable than the (R)-form, with a good fit into the binding site covered by helices 1, 3, and 6 of human dopamine transporter (hDAT). In contrast, the (R, S)-configuration of compound 28 was more stable than that of other isomers and was firmly placed in the binding pocket of DAT bound to DA. DA-induced endocytosis of dopamine D₂ receptors was inhibited when they were co-expressed with DAT, which lowered extracellular DA levels, and uninhibited when they were pretreated with compound 9 or 28. In summary, this study revealed critical structural features responsible for the inhibition of DA reuptake and the functional role of DA reuptake inhibitors in regulating D₂ receptor function.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1143-1148
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• 2010

We investigated the separation of nitrogen heterocyclic compound (NHC) contained in a model coal tar fraction comprising four kinds of NHC [indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine (Qu)], three kinds of bicyclic aromatic compound (BAC) [1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN) mixture with ten structural isomers (DMNs; regarded as one component)], biphenyl (Bp) and phenyl ether (Pe) by liquid membrane permeation (LMP). A batch-stirred tank was used as the permeation unit. An aqueous solution of saponin and n-hexane were used as the liquid membrane and the outer oil phase, respectively. Yield and selectivity of individual NHC was much larger than that of BAC, Bp and Pe. Increasing the initial mass fraction of the saponin to the membrane solution ($C_{sap,0}$) and the initial volume fraction of O/W emulsion to total liquid in a stirred tank (${\phi}_{OW,0}$) resulted in deteriorating the yield of individual NHC, but increasing the stirring speed (N) resulted in improving the yield of each NHC. With increasing $C_{sap,0}$, the selectivity of each NHC based on DMNs increased. Increasing ${\phi}_{OW,0}$ and N resulted in decreasing the selectivity of individual NHC based on DMNs. At an experimental condition fixed, the sequence of the yield and selectivity in reference to DMNs for each NHC was Q > Qu = iQ > In. Furthermore, we compared LPM method with methanol extraction method in view of the separation efficiency (yield, selectivity) of NHC.

• The Plant Pathology Journal
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• 제27권4호
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• pp.342-348
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• 2011

Bacillus subtilis EBS05, an endophytic bacteria strain isolated from a medicinal plant Cinnamomum camphor, can produce antagonistic compounds that effectively inhibit plant pathogenic fungi. The greenhouse experiments showed that wheat sharp eyespot disease (WSED) was reduced by 91.2%, 88.2% and 43.0% after the treatment with fermentation broth, bacteria-free filter and a fungicide fludioxonil, respectively. The culture broth of strain EBS05 can more effectively control WSED than can fludioxonil. The fermentation broth and bacteria-free filter ability to suppress WSED was not significantly different, suggesting that an active secreted substance played a major role in controlling WSED. Separation and purification of the active compounds was carried out by serial processes, including hydrochloric acid (pH 2.0) treatment, methanol extraction and Sephadex LH-20 column chromatography, silica gel column chromatography and reverse-phase high-pressure liquid chromatography (HPLC), respectively. The purified compounds, one of active peaks in the HPLC spectrum, were obtained from the collection. Analysis of the chemical structures by time-of-flight mass spectrometry (TOF-MS) and electrospray ionization mass spectrometry/mass spectrometry (ESI-MS/MS) showed that the active substances produced by the endophytic bacteria EBS05 are mixture of the ${\beta}$-hydroxy-C12~C15-$Leu^7$ surfactin A isomers with 1035.65 Da, 1021.64 Da, 1007.63 Da and 993.65 Da molecular weights, respectively.