• 한국연초학회지
• /
• 제24권2호
• /
• pp.94-100
• /
• 2002

Cyclodextrin glucanotransferase from Bacillus stearothemophilus and Bacillus macerans synthesized maltol and ethyl maltol monoglucoside, with a series of its maltooligo-glucosides by transglycosylation with dextrin as a donor, and maltol or ethyl maltol as an acceptor. The monoglucoside formed from reaction mixture of maltol or ethyl maltol by the successive actions of Bacillus stearothemophilus cyclodextrin glucanotransferase and Rhizopus glucoamylase was isolated by Diaion HP-20 column and silica gel column chromatography. The structure of the isolated monoglucoside was identified as maltol-$\alpha$-D-glucoside and ethyl maltol-$\alpha$-D-glucoside, respectively, by FAB-MS, UV, $^1$H-NMR, $^{13}$ C-NMR spectra and products by hydrolysis with acid, $\alpha$ - and $\beta$ -glucosidases.

• Bulletin of the Korean Chemical Society
• /
• 제18권4호
• /
• pp.369-373
• /
• 1997

When 1H NMR spectra of pyridine, 4-amino-, 4-methyl-, and 4-cyanopyridine coordinated to the paramagnetic polyoxometalate, [SiW11CoⅡO39]6- in D2O are compared, both α- and β-proton peaks are shifted upfield as the basicity of the ligand decreases. The isotropic shifts are separated into contact and pseudocontact contributions by assuming that the contact shifts are proportional to the isotropic shifts of the same ligands coordinated to [SiW11NiⅡO39]6-. This separation reveals that the shift variations with the axial ligand basicity are dominated by changes in the magnetic anisotropy (pseudocontact shift) of [SiW11CoⅡ(ptl)O39]6- (ptl=pyridine-type ligand). The magnitude of the magnetic anisotropy in a series of pyridine-type ligands increases linearly as the pKa of their conjugate acids decreases.

• Macromolecular Research
• /
• 제17권5호
• /
• pp.289-295
• /
• 2009

Low viscosity aromatic hyperbranched polyester epoxy resin (HTBE) was synthesized by the reaction between epichlorohydrin (ECH) and carboxyl-end hyperbranched polyester (HTB) which was prepared from inexpensive materials $A_2$ (1,4-butanediol glycol, BEG) and $B_3$ (trimellitic anhydride, TMA) by pseudo one-step method. The molar mass of the HTB was calculated from its acid value by "Recursive Probability Approach". The degree of branching (DB) of the HTB was characterized by model compounds and $^1H$ NMR-minus spectrum technology, and the DB of the HTB was about $0.47{\sim}0.63$. The viscosity and epoxy equivalent weight of the HTBE were $3,600{\sim}5,000\;cp$ and lower than 540 g/mol respectively. The reaction mechanism and structure of the $AB_2$ monomer, HTB and HTBE were investigated by MS, $^1H$ NMR and FTIR spectra technology. The molecular size of HTBE is under 8.65 nm and its shape is ellipsoid-like as determined by molecular simulation.

• Journal of Applied Biological Chemistry
• /
• 제59권1호
• /
• pp.19-23
• /
• 2016

A phenol substance was extracted from Pinus koraiensis Siebold et Zucc leaf extracts and its biological efficacy was measured. The highest content of the phenol substance contained in Pinus koraiensis Siebold et Zucc leaves was 13.5 mg/g, which was obtained when it was extracted with 80% ethanol. At a concentration of 200 mg/mL, the phenolic substances extracted with 80% ethanol and water showed antimicrobial activities against Helicobacter pylori, producing clear zones of 10 and 12 mm diameter, respectively. Pinus koraiensis Siebold et Zucc. leaf extracts were separated using a Sephadex LH-20 column and 4 fractions were obtained (fractions A-D). Fractions C and D showed the greatest inhibitory activity against Helicobacter pylori producing 10.1 and 12.3 mm clear zones, respectively. These two fractions were purified using a Sephadex LH-20 and MCI-gel column ($H_2O{\rightarrow}100%$ ethanol). Purified compounds A and B were identified as syringic acid and compound C was identified as p-coumaric acid based on $^1H$-nuclear magnetic resonance (NMR), $^{13}C$-NMR, and fast atom bombardment mass spectrometry spectra. When two or more purified compounds were mixed, a synergistic effect of anti-Helicobacter pylori activity was evident. This result indicates that extracts of Pinus koraiensis Siebold et Zucc leaves could be considered a functional food because of their high antimicrobial properties.

• Bulletin of the Korean Chemical Society
• /
• 제25권5호
• /
• pp.715-720
• /
• 2004

Amineterminated, ethylenediamine core polyamidoamine starburst dendrimers of generation 2 (G2), generation 4 (G4) and generation 6 (G6) have been successfully surface-modified via an amide coupling reaction with 4-ethyl, 4'-(3-propionic) bipyridinium cation and the electrochemical behavior of the resulting dendrimers were investigated in aqueous potassium chloride electrolyte solutions. The 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide-mediated reaction resulted in 25-39% end-group functionalization. The water-soluble 4-ethyl, 4'-(3-propylamide) bipyridinium dibromide dendrimers (G2-V2+, G4-V2+ and G6-V2+) were characterized by $^1H$ NMR and UV-Vis spectroscopic methods. The cyclic voltammetric and chronoamperometric experiments were performed to determine the diffusion coefficient and the number of electrons transferred in the process of the first reduction of the viologen-functionalized dendrimers. Adsorption of viologen-functionalized dendrimers at electrode surface was evidenced in the voltammograms. Experimentally determined diffusion coefficients were in good agreement with the values expected from the Stokes-Einstein relation, while the number of electrons transferred concurred with the extent of functionalization determined by $^1H$ NMR and UV-Vis spectra.

• 한국자기공명학회논문지
• /
• 제26권4호
• /
• pp.46-50
• /
• 2022

Antifreeze proteins (AFPs) bind to the ice crystals and then are able to inhibit the freezing of body fluid at subzero temperatures. Type III AFPs are categorized into three subgroups, QAE1, QAE2, and SP isoforms, based on differences in their isoelectric points. We prepared the QAE2 (AFP11) and SP (AFP6) isoforms of the notched-fin eelpout AFP and their mutant constructs and determined their temperature gradients of amide proton chemical shifts (𝚫δ/𝚫T) using NMR. The nfeAFP11 (QAE2) has the distinct 𝚫δ/𝚫T pattern of the first 3₁₀ helix compared to the QAE1 isoforms. The nfeAFP6 (SP) has the deviated 𝚫δ/𝚫T values of many residues, indicating its backbone conformational distortion. The study suggests the distortion in the H-bonding interactions and backbone conformation that is important for TH activities.

• 대한화학회지
• /
• 제40권9호
• /
• pp.623-629
• /
• 1996

지의류에 속하는 Umbiliciaria vellea 중 에탄올 분획의 항균활성 물질을 규명하기 위하여 silica겔 컬럼 크로마토그래피 및 재결정법으로 화합물 I과 II를 순수히 분리정제하여 그 구조와 항균활성을 측정하였다. 정제된 화합물I은 Cryptococcus neoformance 등의 균에 대한 항진균활성과, Pseudomonas aeruginosa등의 균에 대한 항세균 활성이 있었다. 이 물질의 녹는점은 129~132$^{\circ}C$였고, 217, 265 및 330 nm의 UV 최대흡광을 보였다. 그리고 EI-mass에서 측정된 분자이온은 m/z 196이었고, 원소분석 결과 분자식은 $C_{10}H_{12}O_4$였으며 IR 및 NMR 스펙트라로부터 이 물질이 ethyl 2,4-dihydroxy-6-methyl benzoate임을 확인하였다. 화합물 II의 녹는점은 58~59$^{\circ}C$였고, 212, 276 및 282 nm의 UV 최대흡광을 보였다. 이 물질의 분자이온은 m/z 124였고, $C_7H_8O_2$의 분자식을 갖는 5-methyl-1,3-benzenediol임을 확인하였다.

• Bulletin of the Korean Chemical Society
• /
• 제33권9호
• /
• pp.2981-2984
• /
• 2012

Active site mapping has been done for ${\Delta}^5$-3-ketosteroid isomerase (KSI) by analyses of paramagnetic effect on $^1H-^{15}N$ HSQC spectra using 4-hydroxyl-2,2,6,6-tetramethylpiperidinyl-1-oxy (HyTEMPO) and an intermediate analog (equilenin). Our result revealed that residues in hydrophobic cavity of KSI, particularly active site region, mainly experienced a high line-broadening effect of NMR signal with HyTEMPO, while they experienced full recovery of a lineshape upon the addition of equilenin. The mapped region was very similar to the active site of KSI as described by the crystal structure. These observations indicate that a combined use of paramagnetic reagent and substrate (or analog) could rapidly identify the residues in potential active site of KSI, and can be applied to the analysis of both active site and function in unknown protein.

• 임산에너지
• /
• 24권2호
• /
• pp.16-23
• /
• 2005

삼지구엽초의 각 부분(잎, 줄기, 뿌리)을 MeOH로 추출한 후 농축하고 핵산, 클로로포름, 부탄올, 에틸아세테이트 및 수용성으로 분획하여 동결건조하였다. 각 추출물은 메탄을 수용액 및 에탄올-핵산 혼합액을 사용하여 Sephadex LH-20 칼럼크로마토그래피로 화합물을 분리 한 후 TBA 및 6% 초산에 전개하는 셀룰로오스 박층 크로마토그래피로 단리물질을 확인하였다. 단리물질의 화학적 구조는 $^1H-NMR,\;^{13}C-NMR$ 및 질량 분석으로 결정하였으며 단일화합물로 정제된 물질은 caffeic acid를 비롯하여 flavonoid와 그 배당체 화합물인 icariin, caffeic acid, hyperoside, Ikarisoside A, (+)-catechin이었다. 또한, 각 부분의 클로로포름 분획을 GC/MS (Libraries search)를 이용하여 정성분석을 실시하였다.

• Archives of Pharmacal Research
• /
• 제19권2호
• /
• pp.153-159
• /
• 1996

A new streptothricin family antibiotic producing Streptomyces spp. SNUS 8810-111 was isolated from a soil sample. Study of its morphological and physiological characters indicated that the antibiotic producing organism was a Streptomyces spp. Taxonomical studies suggested that the organism might belong to the genus streptomyces gougeroti. The organism produced antibiotics most in calcium carbonate-tryptic soy broth. The active principles were recovered from the broth with a cation exchange resin and eluted from the resin with HCI. Cellulose column chromatography gave two active principles.$^1H-^1H$ Homo-COSY study on the first compound revealed four structural components. Total hydrolysis of the antibiotic with HCI allowed isolation of $\beta-lysine$. From these data the antibiotic was found to be streptothricin D. The other compound showed one additional signal in the .$^1H$NMR and the $^{13}C$ NMR spectra. The signal was from a methyl group attached to a nitrogen atom. Comparison of the NMR signals with those of streptothricin D suggested that the compound was N-methyl-streptothricin D which was a new compound in the family of streptothricin antibiotics.