• Archives of Pharmacal Research
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• v.18 no.6
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• pp.381-384
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• 1995

Covalent binding of the reactive metabolites of SC_42867 to microsomal proteins has been examined. In the absence of inhibitor of cytochrome oxydase (.alpha.-naphtyl-isothiocyanate) or a radical scavenger (3-terthiobuty-4-hydroxyanisol), up to 4.0% of total redioactivity used in the assay could irreversibly bind to proteins. In the presence of an inhibitor, the highest percentage of covalent binding observed is 0.7% a significant decrease of the metabolism of SC42876 was observed. These results suggest in a cytochrome P-450 dependent generation of SC_42867 metabolites significantly take part in the covalent binding process.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.104-111
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• 2001

There are some evidence that active enzymatic proteins, e.g. fungal laccase, exist in the naturally occured soil humus. This study was performed to investigate the covalent binding of fungal laccase to the humic acid-iron complex, and to measure laccase activity of immobilized ones. Seven methods were adopted to form the covalent binding of fungal laccase with soil humic acids complexed with iron. Using these seven methods it was possible to change the dimension of spacer arm between laccase and support, and also to regulate the mode of covalent binding of this enzyme. The spacer arm was regulated from 2C to 11C. There was not observed any straight relationship between the spacer arm longitude and the laccase activity after immobilization, but the binding mode more effective than the former. Three out of the seven methods gave the high activity of immobilized laccase, and which active products of laccase immobilization was stable up to 10 days after the process. It is indicated that natural soil condition might be prevented the laccase activation by the toxic influence of some phenolic humic compounds. It was shown, for the first time, the possibilities to obtain the high activity of fungal laccase by binding to humic acids, and especially in complex with iron.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.248-254
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• 2012

During the monolayer assembly of zeolite microcrystals using sonication with stacking (SS) method, the factors that govern the degree of close packing (DCP) between the microcrystals, the rate of attachment (rA) of microcrystals onto the substrate, the degree of coverage (DOC), and the binding strength (BS) between each crystal and the substrate were investigated for each mode of binding linkage (MBL). The tested MBLs were covalent linkage (CL), ionic linkage (IL), and polyelectrolyte-mediated ionic linkage (p-IL). Unlike the monolayers of zeolite crystals assembled on glass with a covalent linkage, the strong BS, very high DOC, and very high DCP do not decrease during monolayer assembly on glass through ionic linkages. This results indicate that the surface migration of crystals undergo linkage-nondestructively when crystals were attached to the substrates through ionic linkages.

• Toxicological Research
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• v.16 no.3
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• pp.221-227
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• 2000

A 6-sulfooxymethylbenzo[a]pyrene (SMBP), the ultimate metabolite of methyl-substituted benzo[a]pyrene (BP), has been found to be carcinogenic in mice. These properties may be attributable to its strong reactivity with cellular macromolecules such as DNA. However, serum and its major constituent albumin attenuated significantly the cytotoxicity and mutagenicity of 5MBP in bacterial and mammalian cell systems. This inhibitory activity of serum against 5MBP-induced cytotoxicity and mutagenicity in Chinese hamster V79 cells appears to be caused by the reduced macromolecular adducts such as DNA and proteins, but serum failed to reduce 5MBP binding to naked calf thymus DNA. A number of proteins in the serum could act as nucleophiles that are able to intercept reactive chemicals through covalent binding. Albumin present in the plasma seems to be one of major components responsible for direct binding with 5MBp, thereby reducing its reactivity to genetic materials. We here determined which fraction is preferential for 5MBP binding through fractionation of 5MBP-treated serum with ammonium sulfate. The albumin-containing fraction had slightly more affinity for 5MBP than the immunoglobulin-containing fraction. Our results indicate that the covalent modification of plasma proteins may reduce 5MBP-induced damage.

• Toxicological Research
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• v.13 no.3
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• pp.257-263
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• 1997

Pentachlorophenol(PCP) which ks widely used in wood preservation, pulp and paper mills, has led to a substantial envirortmental contamination. To get the reliable data for the effective health risk assessment with PCP, covalent binding potential of PCP to cellular macromolecules and glutathione(GSH) was investigated after intraperitoneal administration of $^{14}C-PCP$ to rats. PCP metabolites were able to bind covalently to serum albumin and hepatic protein in a dose- and time-dependent manner. Hepatic protein adducts of PCP metabolites were increased as a function of cytochrome P-450 activities, whereas, albumin adducts significantly decreased. Covalent binding of PCP metabolites with DNA or hemoglobin was not observed. GSH levels in liver tissue decreased over 12hrs, however, the level was recovered after 48hrs. Tetrachloro-1,4-benzoquinone (1,4-TCBQ), one of the most reactive PCP metabolites, conjugated with GSH very rapidly. Base on our results, we could conclude that PCP metabolized to reactive electrophilic metabolites by cytochrome P-450 isoenzymes and conjugated rapidly with neighboring protein or nonprotein sulfhydryl before reacting with DNA or hemoglobin. We propose that albumin adducts and mercapturic acids of PCP metabolites can be used good biomarker of recent PCP exposure.

• Archives of Pharmacal Research
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• v.16 no.2
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• pp.89-93
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• 1993

Incubation of $S(-)-^3H$-nicotine with rabbit lung microsomes in the presence of dioxygen and NADPH results in the formation of metabolities that bind covalently to microsomal macro-molecules. The addition of cytochrome P-450 monooxygenase inhibitors, $\alpha$-methylbenzyl ami-nobenzotriazole and aroclor 1260, inhibited both (S)-nicotine metabolism and covalent binding. The relative rates of oxidation of nicotine $\Delta^{1',5'}$ iminium ion to continine indicates that lung $100,000\times{g}$ supematant catalyzed this oxidation approximately 18 times slower than that of liver system based on mg of protein, and increased covalent interactions. Since than that of liver system based on mg of protein, nd increased covalent interactions. Since the activity of lung iminium oxidase appears much lowr than the liver, it is tempting to speculate that localized concentrations of nicotine $\Delta^{1',5'}$ iminium ion in the lung will survive for a longer period of time. These results support that cytochrome P-450 catalyzed oxidation of nicotine leads to the formation of reactive nad electrophilic intemediates capable of chemical interactions with biomacromolecules.

• KSBB Journal
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• v.20 no.3
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• pp.133-141
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• 2005

This review presents the preparation, transport mechanism and application of molecularly imprinted membranes (MIM). Molecular imprinting has now been established as a technique which allows the creation of tailor-made binding sites for many classes of compounds. MIM have some advantages; a high capacity due to a large surface area, faster transport of substrate molecules and faster equilibrium of binding cavities compared to molecularly imprinted particles. MIM were prepared by covalent and non-covalent chemical bonding systems, by interactions between functional monomer and template. MIM can be prepared by in-situ polymerization, wet phase inversion, dry phase inversion, and surface imprinting method. MIM can continuously separate mixtures based on facilitated or retarded diffusion of the template. MIM can change their permeability in the presence of templates. MIM have a potential to be used to separate chiral compounds and materials with similar structures. However the application of MIM by the chemical industries is still in its infancy stages.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.2
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• pp.16-21
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• 2011

Immobilization of biosorbent is very important for application to real wastewater treatment process because biosorbent itself does not have enough tough structure. Therefore, resent research on heavy metal biosorption using biomass has been focused on its efficient immobilization method. To improve the mechanical strength of freely biosorbent, many immobilization methods have been suggested for applications to the biosorbent such as microorganisms or polysaccharides. In this study, various immobilization methods such as adsorption, covalent binding, entrapment, encapsulation, and crosslinking will be introduced.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.320-325
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• 1997

Transglucosidase (TG) from Aspergillus niger was immobilized on various carriers by several immobilization methods such as ionic binding, adsorption, entrapment, covalent linkage and metal chelation to improve the process performance. The covalent linkage with CNBr-activated sepharose 4B was found as the best method for immobilization of TG based on the immobilization yield which was 61.3%. The immobilization through ionic binding and adsorption gave 33.1% and 22.5% yield respectively but both methods were not selected due to lower yield than covalent linkage using CNBr-Sepharose 4B. Internal diffusion resistance in beads developed by entrapment were not suitable factor in producing final target products. Covalent linkage of TG on magnesium silicate, silica gel and glass bead and metal chelation method didn't result in higher yield than the selected one, either.

• Journal of Hydrogen and New Energy
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• v.25 no.6
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• pp.602-608
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• 2014

The sequence of bond overlap population of metal hydrogen binding is in Al-H > Fe-H > Zr-H > V-H. This results shows the binding energy of Al-H is the biggest in this metals (Al, Fe, Zr, and V) and hydrogen interaction. The Vanadium-hydrogen binding shows the weakest binding energy compared to other metals and it causes easy hydrogen desorption from the corresponding metals. The net charge of Al-H show the biggest value of 0.2248 and the severe localizations of electrons around aluminum and imply strongest covalent binding nature in these metals. This study is applicable to the purification of hydrogen in other bulk gas.