• Bulletin of the Korean Chemical Society
• /
• 제31권5호
• /
• pp.1262-1266
• /
• 2010

In this study, we investigated the use of liquid crystals to selectively detect the activity of enzymes at interfaces decorated with oligopeptide-based membranes. We prepared a mixed monolayer of tetra(ethylene glycol)-terminated lipids and carboxylic acid-terminated lipids at the aqueous-liquid crystal (LC) interface. The 17 amino-acid oligopeptide SNFKTIYDEANQFATYK was then immobilized onto this mixed monolayer through N-hydroxysuccinimide-activation of the carboxylic acid groups. We examined the orientational behavior of nematic 4-cyano-4'-pentylbiphenyl (5CB) after conjugation of the 17 amino-acid oligopeptide with the mixed monolayer assembled at the interface. Immobilization of the oligopeptide caused orientational transitions in 5CB, with a change from homeotropic (perpendicular) to tilted alignment, which was primarily due to the reorganization of the monolayer. The orientation of the 5CB molecules returned to its homeotropic state after contacting the interface containing ${\alpha}$-chymotrypsin, which can cleave the immobilized oligopeptide. Control experiments confirmed that the enzymatic activity of ${\alpha}$-chymotrypsin triggered the ordering transitions in the LC. These results suggest that the LC can provide a facile method for selective detection of enzymatic activity.

• 약학회지
• /
• 제37권3호
• /
• pp.295-305
• /
• 1993

In order to develop oral cephalosporin having a new substituent at 3 position, the synthesis of cephalosporins modified at C-3 and the effect of the substituents on the oral absorption is studied. 7-[(Z)-2-(2-Aminothiazole- 4-yl)-2-methoxyiminoacetamidol-3-[4-(2-pyridyl )piperazinyl] thiocarbonylthiomethyl-3-cephem-4-carboxylic acid (CEN1) and 7-[(Z)-2-(2-aminothiazole-4-yl)-2-methoxyiminoacetamido]-3-[4-(2-pyrimid yl)piperazinylthiocarbonylthiomethyl-3-cephem-4-carboxylic acid (CEN2) were synthesized from 4-(2-piridyl)piperazinyl dithiocarbamate potassium salt or 4-(2-pirimidyl)piperazinyl dithiocarbamate potassium salt and cefotaxime. Also pivaloyloxymethyl esters of CEN1 and CEN2, pivaloyloxymethyl 7-[(Z)-2-(2-aminothiazole-4-yl)-2-methoxyiminoacetamido]-3-[4-(2-pyridyl )piperazinyllthiocarbonylthiomethyl-3-cephem-4-carboxylate (CENIP) and pivaloyloxymethyl 7-[(Z)-2-(2-aminothiazole-4-yl)-2-methoxyiminoacetamidol-3- [4-(2-pyrimid yl)piperazinyllthiocarbonylthiomethyl-3-cephem-4-carboxylate (CEN2P) were synthesized. The in vitro activities of two new oral cephalosporins, CEN1 and CEN2, were compared with the in vitro activities of cefaclor and cefotaxime against a variety of bacterial species. CEN2 has a broad antibacterial spectrum covering Gram-positive and Gram-negative bacteria, similar to that exhibited by CEN1 and cefotaxime. CEN1 and CEN2 were more active in vitro than cefaclor against Streptococcus pyogenes, Klebsiella aerogenes and Enterobacter cloacae.

• Journal of Microbiology and Biotechnology
• /
• 제20권3호
• /
• pp.587-593
• /
• 2010

Three hundred and seventy-four rhizobacteria were isolated from the rhizosphere soil (RS) or rhizoplane (RP) of Echinochloa crus-galli, Carex leiorhyncha, Commelina communis, Persicaria lapathifolia, Carex kobomugi, and Equisetum arvense, grown in contaminated soil with petroleum and heavy metals. The isolates were screened for plant growth-promoting trait (PGPT), including indole acetic acid (IAA) productivity, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and siderophore(s) synthesis ability. IAA production was detected in 86 isolates (23.0%), ACC deaminase activity in 168 isolates (44.9%), and siderophore(s) synthesis in 213 isolates (57.0%). Among the rhizobacteria showing PGPT, 162 isolates had multiple traits showing more than two types of PGPT. The PGPT-possesing rhizobacteria were more abundant in the RP (82%) samples than the RS (75%). There was a negative correlation (-0.656, p<0.05) between the IAA producers and the ACC deaminase producers. Clustering analysis by principal component analysis showed that RP was the most important factor influencing the ecological distribution and physiological characterization of PGPT-possesing rhizobacteria.

• Elastomers and Composites
• /
• 제49권3호
• /
• pp.191-198
• /
• 2014

산성기를 도입한 폴리우레탄에 나노산화아연을 첨가하여 열가소성 폴리우레탄 탄성체를 합성하였으며, 합성된 폴리우레탄 탄성체의 기계적물성, 열적특성, 접촉각, 그립특성을 평가하였다. 그리고 산화아연의 함량과 입자 크기가 폴리우레탄 탄성체에 미치는 영향에 대해서 연구하였다. 나노산화아연을 도입한 경우 이온결합이 형성되어 산성기에 의한 수소결합과 동시에 작용하기 때문에 인장강도, 마모 등 기계적 물성 및 그립특성이 향상되는 것이 확인되었다. 폴리우레탄내의 산화아연 함량에 따른 물성평가 결과 나노산화아연 함량이 증가할수록 이온결합 도입에 의한 친수성이 커져서 wet slip이 지속적으로 상승되었으며, 기계적 물성은 산화아연에 의한 이온화율 50%까지 향상되다가 그 이후에는 감소되는 현상을 나타내었다.

• Bulletin of the Korean Chemical Society
• /
• 제25권12호
• /
• pp.1898-1906
• /
• 2004

Nonclassical quinazolinone analogs I, II, and III, in which the glutamic acid moiety of the classical antifolates is substituted by phenylglycine, phenylalanine or aminobenzoic acid and their methyl esters, were synthesized and evaluated as lipophilic inhibitors of thymidylate synthase (TS). The target compounds were generally potent inhibitors of L. casei and human TS with $IC_{50}$ values within the narrow range of 0.2-10 ${\mu}$M and 0.003-0.03 ${\mu}$M, respectively. Further, most of the target compounds showed cytotoxicity against tumor cell lines of murine and human origin with $IC_{50}$ values of as low as 0.050 ${\mu}$M. Substitution of another hydroxyl or carboxylic acid/ester group at the phenyl ring further increased the potency of TS inhibition and cell growth inhibition. Most effective were compounds If and Ic in which extra carboxylic acid/ester was present at the phenyl ring with nanomolar $IC_{50}$ values of 0.0044 and 0.0093 ${\mu}$M against human TS and submicromolar cytotoxic growth inhibition against all four tumor cell lines.

• 한국분말재료학회지
• /
• 제14권4호
• /
• pp.256-260
• /
• 2007

The surface of magnetite ($Fe_{3}O_{4}$) nanoparticles prepared by coprecipitation method was modified by carboxylic acid group of poly(3-thiophenacetic acid (3TA)) and meso-2,3-dimercaptosuccinic acid (DMSA). Then the lysozyme protein was immobilized on the carboxylic acid group of the modification of the magnetite nanoparticles. The magnetite nanoparticles are spherical and the particle size is approximately 10 nm. We measured quantitative dispersion state by dispersion stability analyzer for each $Fe_{3}O_{4}$ nanoparticles with and without surface modification. The concentration of lysozyme on the modified magnetite nanoparticles was also investigated by a UV-Vis spectrometer and compared to that of magnetite nanoparticles without surface modification. The functionalized magnetite particles had higher enzymatic capacity and dispersion stability than non-functionalized magnetite nanoparticles.

• Korean Membrane Journal
• /
• 제3권1호
• /
• pp.9-16
• /
• 2001

The diamide-diamine having carboxylic acid was prepared by direct condensation of 1,2,4-benzenetricarboxylic acid with bits[4- (3-aminophenoxy ) phenyl] sulfone and bits(4-aminouhenyl)-1,4- diisopropylbenzene in medium consisting of triphenylphosphite, LiCl, and N-methyl-2-pyrrolidone. Copoly (amide-imide) derivatives with high molecular weight could be synthesized by one-step polycondensation of prepared diamide-diamine having carboxylic acid and various dianhydride compounds. Depending on the chemical structure and composition of polymer backbones, the viscosities of polymers were found to range between 0.87∼ 1.57 dL/B. All the polymers showed good thermal stability up to 320$\^{C}$ and the 10% weight loss temperature was observed in the range of 450∼540$\^{C}$ in a thermogravimetric traces. The glass transition was recorded in the temperature range of 200 ∼ 270$\^{C}$. All the polymers showed an amorphous nature on a differential scanning calorimetric thermograms. These polymers generally had good mechanical properties and readily soluble in various polar solvents. Further, it was proved that their properties could be determined from the composition.

• 한국작물학회지
• /
• 제30권2호
• /
• pp.184-189
• /
• 1985

질소수준이 높아짐에 따라서 벼 엽신에서 에칠렌 생성량이 감소하는 원인에 대하여 에칠렌생합성계에 존재하는 전구물질 메치오닌 및 직접전구물질 ACC등을 벼에 처리하여 에칠렌생성량에 미치는 영향을 검토한 결과를 요약하면 다음과 같다. 1. 벼 유묘 및 엽에 메치오닌을 처리하면 처리농도가 높을수록 에칠렌생성량은 증가하였다. 2. 직접전구물질인 ACC를 엽신에 처리하면 처리농도가 높을수록 에칠렌생성량은 직선적으로 증가하였다. 3. 질소수준이 다를 벼의 유묘 및 엽신에 메치오닌 및 ACC를 처리하면 에칠렌생성량은 증가하나 질소수준이 높아질수록 에칠렌생성량은 현저히 억제 되어진다.

• Carbon letters
• /
• 제2권3_4호
• /
• pp.170-175
• /
• 2001

A petroleum-based isotropic pitch fiber spun by melt-blown method was oxidized in air flow at various conditions. The oxidized pitch fiber obtained was tested for its infusibility and its elemental composition during the process of stabilization. The structural changes were traced by using solvent solubility, FT-IR spectroscopy, and elemental analysis. The samples showed a gradual increase in weight with increasing the oxidization temperature. The weight gain of sample oxidized at $320^{\circ}C$ for 10 min was about 4.5%. The concentration of the pyridine and toluene soluble fraction decreased with an increase in stabilization temperatures. The oxygen uptaken in the stabilization process converted aliphatic side chains into the carbonyl groups. As stabilization proceeded, the more ether and carboxylic acid groups were formed through the oxidations of aldehyde and primary alcohol, and then the carboxylic acid was dehydrated to be aromatic anhydride.

• 한국미생물·생명공학회지
• /
• 제23권1호
• /
• pp.98-103
• /
• 1995

During the screening of antifungal antibiotics from microbial metabolites, we selected Pseudomonas aeruginosa KGM-100 showing powerful antagonistic activity against various phytopathogenic fungi. Antibiotics KGM-100A and KGM-100B were purified from the culture broth of Pseudomonas aeruginosa KGM-100 by diaion HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, preparative TLC and recrystallization. KGM-100A which was recrystallized in MeOH showed antimicrobial activities against a broad spectrum of fungi and bacteria. Physico-chemical properties of KGM-100A were determined and identified to be phenazine-l-carboxylic acid by UV, IR, $^{1}$H-NMR, $^{13}$C-NMR, mass spectrum, and elemental analyses.