• The Korean Journal of Physiology
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• v.30 no.1
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• pp.53-62
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• 1996

Transepithelial transport of tetraethylammonium (TEA) was studied in monolayers of opossum kidney cells cultured on permeable membrane filters. $[^{14}C]-TEA$ was transported across the OK cell monolayer from basolateral to apical side by a saturable process which can be stimulated by acidification of the apical medium. The apparent Michaelis-Menten constant $(K_{m})$ and the maximum velocity$(V_{max})$ for the transport were $41\;{\mu}M$ and 147 pmole/ mg protein/ min, respectively. The transport was significantly inhibited by unlabelled TEA, amiloride, cimetidine, choline, and mepiperphenidol added to the basolateral side at 1 mM and was slightly inhibited by 5 mM $N_{1}-methylnicotinamide\;(NMN).$ Unlabelled TEA added to the apical side stimulated the $basolateral-to-apical\;{^{14}C}-TEA$ transport, suggesting that the TEA self-exchange mechanism was involved at the apical membrane. Sulfhydryl reagents such as ${\rho}-chloromercuribenzoic\;acid\;(PCMB)\;and \;{\rho}-chloro-mercuribenzene\;sulfonate \;(PCMBS)$ and carboxyl reagents such as N,N'-dicyclohexylcarbodiimidem (DCCD) and N-ethoxy-carbonyl-2-ethoxy-1,2-dihydro-quinoline(EEDQ) inhibited the TEA transport at both the basolateral and apical membranes of the OK cell monolayer. These results suggest that OK cell monolayers possess a vectorial transport system for organic cations which is similar to that for organic cation secretion in the renal proximal tubule.

• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.107-111
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• 1989

Glucoamylase was inactivated with 1-ethyl-2-(dimethylaminopropyl)carbodiimide (EDC) at pH 5.0. Time course of inactivation of glucoamylase was at least biphasic. From the results of the titration of SH groups with Ellman's reagent and hydroxylamine treatment at pH 7.0, it was concluded that the crucial sites of modification were carboxyl groups of glucoamylase. The CD spectrum of EDC-modified glucoamylase suggested that the gross conformation of the native enzyme was retained. The inactivation of glucoamylase was reduced remarkably in the presence of maltose. The logarithm of the half-life of the inactivation of glucoamylase by EDC was a linear function of log[EDC] in each stage indicating that one carboxyl group among the modified ones was crucial for inactivation of glucoamylase. The change in the binding affinity due to modification was determined by using an affinity column. It indicates that the carboxyl group of glucoamylase seems to play a role in both, the catalysis and substrate binding in the first stage, but in the second stage the binding affinity is recovered almost up to that of native enzyme.

• YAKHAK HOEJI
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• v.31 no.5
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• pp.315-321
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• 1987

A high performance liquid chromatographic method was developed for the determination of glycyrrhetinic acid contained in licorice powder. Glycyrrhetinic acid which is hydrolysate of glycyrrhizin extracted from licorice powder, was determined with good result by HPLC using 2-bromoacetyltriphenylene labeling reagent. The glycyrrhetinic acids were labeled with 2-bromoacetyltriphenylene in acetonitrile using 18-crown-6-ether and KOH as a catalyst. Derivatized glycyrrhetinic acids were separated from the extracted licorice powder on a reversed-phase column (chemopak $C_{18}$) using 100% acetonitrile as a mobile phase and monitored by an UV-detector at 268nm. Linearity of calibration curve was obtained between 5 ng and 20 ng, and the lower limit of detection was 2 ng. The recovery of glycyrrhetinic acid to licorice powder was about 99.3%. This method was sensitive, reliable and useful for, determination of glycyrrhetinic acid.

• Journal of Microbiology and Biotechnology
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• v.26 no.5
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• pp.837-845
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• 2016

A novel endodextranase isolated from Paenibacillus sp. was found to produce isomaltotetraose and small amounts of cycloisomaltooligosaccharides with a degree of polymerization of 7-14 from dextran. To determine the active site, the enzyme was modified with 1-ethyl-3-[3-(dimethylamino)-propyl]-carbodiimide (EDC) and α-epoxyalkyl α-glucosides (EAGs), an affinity labeling reagent. The inactivation followed pseudo first-order kinetics. Kinetic analysis and chemical modification using EDC and EAGs indicated that carboxyl groups are essential for the enzymatic activity. Three Asp and one Glu residues were identified as candidate catalytic amino acids, since these residues are completely conserved across the GH family of 66 enzymes. Replacement of Asp189, Asp340, or Glu412 completely abolished the enzyme activity, indicating that these residues are essential for catalytic activity.

• Journal of Fashion Business
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• v.13 no.1
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• pp.102-114
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• 2009

Chitosan is a polysaccharide with cationic amino groups in its structure and has useful properties as functional materials. Various end-use developments of chitosan are in progress. When the cotton fabric is pretreated with chitosan, the hand property of cotton fabric may be improved expecially for the summer apparel. In this study, as a cross-linking agent to introduce chitosan into cotton, BTCA(butane-1,2,3,4-tetracarboxylic acid) or CA(citric acid) was added in order to prevent detachment of chitosan by the cross-linking. During the cross-linking procedure, via the padding-drying-heat setting, amino groups of chitosan and hydroxyl groups of cotton, carboxyl groups of BTCA/CA are cross-linked by forming anhydrous cyclic rings. Since BTCA has four carboxyl groups, cross-linking by thermal treatment is easy, leading to the trials in wrinkle-recovery treatment of cotton fabrics. However, the high price of the BTCA reagent has been a shortcoming in the actual application for industrial use. Therefore, in this study, we tried the application of CA having three carboxyl groups, which is relatively low priced, as the substituting cross-linking agent. The hand of the treated fabrics were evaluated by measuring physical properties. In addition, based on the physical properties, three-dimensional images were introduced by using 3D CAD systems and results were compared.

• YAKHAK HOEJI
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• v.31 no.2
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• pp.105-111
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• 1987

A high performance liquid chromatographic method was developed for the simultaneous determination of free and glycine conjugated bile acids. Free and glycine conjugated bile acids were extracted from bear gall bladder by methanol and from serum using a Sep-pak $C_{18}$ catridge. The extracted bile acids were labeled with 2-bromoacetyltriphenylene in acetonitrite using 18-crown-6-ether as a catalyst. Derivatized bile acids were separated from the individual bile acids on a reversedphase column (Chemcosorb 5-ODS-H) using acetonitrile-methanol-water(10:50:30) as a mobile phase and monitored by an UV-detector at 254nm. Linearities of calibration curve were obtained between 4 ng and 24 ng, and recoveries from bear gall bladder sample were higher than 94%.

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.86-91
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• 2008

Dicamba(3,6-dichloro-2-methoxybenzoic acid) is used to control for pre and post-emergence of annual and perennial broad-leaf weeds. It is very soluble in water and highly mobile, acidic herbicide. So it is easily moved and detected in groundwater. Zerovalent iron(ZVI) has been used for the reductive degradation of certain compounds through amination of nitro-substituted compounds and dechlorination of chloro-substituted compounds. In this study, we investigated the potential of ZVI for the oxidative degradation of dicamba in water. The degradation rate of dicamba by ZVI was more rapidly increased in pH 3.0 than pH 5.0 solution. The degradation percentage of dicamba was increased with increasing amount of ZVI from 0.05% to 1.0%(w/v) and reached above 90% within 3 hours of reaction. As a result of identification by GC-MS after derivatization with diazomethane, we obtained three degradation products of dicamba by ZVI. They were identified 4-hydroxy dicamba or 5-hydroxy dicamba, 4,5-dihydroxy dicamba and 3,6-dichloro-2-methoxyphenol. 4-Hydroxy dicamba or 5-hydroxy dicamba and 4,5-dihydroxy dicamba are hydroxylation products of dicamba. 3,6-dichloro-2-methoxyphenol is hydroxyl group substituted compound instead of carboxyl group in dicamba. We also confirmed the same degradation products of dicamba in the Fenton reaction which is one of oxidation processes using ferric sulfate and hydrogen peroxide. But we could not find out the dechlorinated degradation products of dicamba by ZVI.

• Journal of Microbiology and Biotechnology
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• v.11 no.1
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• pp.29-34
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• 2001

The mutant enzymes of N-carbamyl-D-amino aicd amidohydrolase (N-carbamylase) from Agrobacterium radiobacter NRRL B11291, showing a negligible activity, were selected from the library generated by random mutagenesis. From the sequence analysis, these mutants were found to contain the amino acids substitutions at Cys172, Glu47, and Glu146. Previously, Cys172 was reported to be necessary for the enzyme catalysis. The chemical modification of the N-carbamylase by carboxyl group specific chemical reagent, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide(EDC), resulted in a loss of activity. The replacement of glutamic acids with glutamines by site-directed mutagenesis led to aggregation of the enzymes. Mutant enzymes fused with maltose binding protein (MBP) were expressed in soluble form, but were inactive. These results indicate that two glutamic acid residues play an important role in structure and function of the N-carbamylase. Multiple sequence alignment of the related enzymes revealed that Glu47 and Glu146 are rigidly conserved, which suggests that tese residues are crucial for the structure and function of the functionally related C-N hydrolases.

• Journal of the Korean Wood Science and Technology
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• v.23 no.2
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• pp.37-46
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• 1995

The substitution of carboxymethylated hydroxyl group in pulp revealed more hydrophilic than hydroxyl group. And then fibers were more flexible, swell more which leads to better conformation between fibers in turn this raise paper strength. In this paper, we tried to chemical modifyings of recycled fiber, OCCs(old corrugated containers). Many researchers have examined chemical modification of papermaking fiber by partial carboxymethylation(PCM) using a organic solvent processes. We made modified PCM processes adapted waters m replace of the organic solvent. Our testings for the optimum conditions on the new method, conditions as reaction time, temperature, liquor ratios were designed likely plant system. Freenesses(SR$^{\circ}$) were increased following on carboxyl content of the samples. Handsheets of untreated samples and partial carboxymethylated OCCs were made by optimum conditions on different concentrations of the reagent. As results, maximum 25% strength increasing effects were obtained by the new method.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.2
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• pp.39-45
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• 2003

This study was performed to develop the new type enzyme immobilization sheet from carboxymethylated refiner mechanical pulp (CRMP) substrate. Enzyme immobilization was attempted to couple carboxyl groups of CRMP with amino groups of the enzyme, trypsin, through the reaction of carbodiimide reagent, 1-ethyl-3-(3-dimethyl aminopropyl)-carbodimide (EDC ). Immobilization carrier, water insoluble CRMP fraction (CRMP-IS), was successfully reacted with the enzyme, formed peptide linkage like -CONH- at 1680$cm^{-1}$ / and new ester linkage like -COO$CH_3$, methylester at 1735$cm^{-1}$ /, and produced enzyme immobilized substrate (CRMP-IST). The enzyme immobilized handsheet was prepared by mixing the above chelated enzyme immobilized substrate(CRMP-IST) with kraft pulp by paper sheet machine like papermaking process. The sheet weight and strength were increased with increasing dosage of CRMP-IST, and decreased at more than 10％ mixing of CRMP-IST, but higher than the controls. Concerning activities of immobilized trypsin(CRMP-IST) sheet by caseinolysis, the teared-off sheet with shaking was shown higher enzyme activities than sheet shape without shaking. In conclusion, this enzyme immobilized sheet would be expected easy handling for practical application and reutilization.