• Toxicological Research
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• 제3권2호
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• pp.97-110
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• 1987

The effects of 5 novel hepatotrophic agents, dithiol malonate derivatives (DMDs; DMD1-DMD5), on the liver microsomal lipid peroxidation induced by carbon tetrachloride $(CCl_4)$ and the correlations with the changes of microsomal electron transport system were investigated. All DMDs were found to inhibit the lipid peroxidation induced by $CCl_4$ in mice and rats as well in vitro liver microsomal system. Therefore, each DMD seemed to have direct mode of action on liver microsomes to inhibit the lipid peroxidation. As an ex vivo study, the induced lipid peroxidation by $CCl_4$ and the changes in electron transport system were determined with liver microsomes obtained from rats chronically treated with DMDs for 7 days. The induced lipid peroxide contents in liver microsomal system were lower in DMD1, DMD2 and DMD3 treated group, but higher in DMD4 and DMD5 group when compared to the control group. Cyt. p.450 contents in the microsomes were decreased by the treatment with DMD1, DMD2 and DMD3, but increased significantly by DMD4 with great extent and by DMD5 with less extent. The cyt. p-450 isozymes induced by treatment of DMD4 and DMD5 were identified as 3-methylcholanthrene (MC) type. The NADPH cyt. -C reductase activities of the microsomes treated with DMD1, DMD2, DMD4 and DMD5 were increased in the range of around 20% to 50%, but decreased with DMD3, All DMDs increased dyt. $-b_5$ content and did not alter NAdH-cyt, $-b_5$ reductase activities in the microsomes. In summary, the 5 novel hepatotrophic agents (DMDs) markedly protected against lipid peroxidation induced by $CCl_4$ in vivo and in vitro possibly through the mechanism of direct action on the liver microsomes. The degree of inhibition produced by DMDs on lipid peroxidation induced by $CCl_4$ seemed to coincide rather with cyt. p-450 contents than with other components of liver microsomal electron transport system including NADPH-cyt, -C reductase.

• BMB Reports
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• 제29권4호
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• pp.277-285
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• 1996

In Pseudomonas fluorescens grown on malonate as sole carbon source, acetyl-CoA synthetase was induced, suggesting that malonate is metabolized through acetate and then acetyl-CoA. Acetyl-CoA synthetase was purified 18.6-fold in 4 steps to apparent homogeneity. The native molecular mass of the enzyme estimated by a native acrylamide gel electrophoresis was 130 kDa. The enzyme was composed of two identical subunits with a molecular mass of 67 kDa. Optimum pH was 70. The acetyl-CoA synthetase showed typical Michaelis-Menten kinetics for the substrates, acetate, ATP and CoA, whose $K_m$ values were calculated to be 33.4, 74.8, and 40.7 mM respectively. Propionate. butyrate and pentanoate were also used as substrates by the enzyme, but the rate of the formation of the CoA derivatives was decreased in the order of the increase in carbon number. The enzyme was inhibited by the group-specific reagents diethylpyro-carbonate, 2,3-butanedione, pyridoxal-5'-phosphate and N-bromosuccinimide. In the presence of substrates the inactivation rate of the enzyme, by all of the group-specific reagents mentioned above decreased, indicating the presence of catalytically essential histidine, arginine, lysine and tryptophan residues at or near the active site. Preincubation of the enzyme with ATP, $Mg^{2+}$ resulted in the increase of its susceptibility to diethylpyrocarbonate, suggesting that ATP, $Mg^{2+}$ may induce a conformational change in the active site exposing the essential histidine residue to diethylpyrocarbonate. The enzyme was acetylated in the presence of acetyl-CoA, indicating that this is one of acyl-enzyme.

• 한국해양생명과학회지
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• 제6권1호
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• pp.1-8
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• 2021

In marine ecosystems, the biosynthesis and catabolism of dimethylsulfoniopropionate (DMSP) by marine bacteria is critical to microbial survival and the ocean food chain. Furthermore, these processes also influence sulfur recycling and climate change. Recent studies using emerging genome sequencing data and extensive bioinformatics analysis have enabled us to identify new DMSP-related genes. Currently, seven bacterial DMSP lyases (DddD, DddP, DddY, DddK, DddL, DddQ and DddW), two acrylate degrading enzymes (DddA and DddC), and four demethylases (DmdA, DmdB, DmdC, and DmdD) have been identified and characterized in diverse marine bacteria. In this review, we focus on the biochemical properties of DMSP cleavage enzymes with special attention to DddD, DddA, and DddC pathways. These three enzymes function in the production of acetyl coenzyme A (CoA) and CO₂ from DMSP. DddD is a DMSP lyase that converts DMSP to 3-hydroxypropionate with the release of dimethylsulfide. 3-Hydroxypropionate is then converted to malonate semialdehyde by DddA, an alcohol dehydrogenase. Then, DddC transforms malonate semialdehyde to acetyl-CoA and CO₂ gas. DddC is a putative methylmalonate semialdehyde dehydrogenase that requires nicotinamide adenine dinucleotide and CoA cofactors. Here we review recent insights into the structural characteristics of these enzymes and the molecular events of DMSP degradation.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1155-1158
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• 2010

Microwave-assisted Michael reaction between EMME and various amines such as diphenylamine, 4-methyl-N-phenylbenzenamine, N-phenylnaphthalen-1-amine, dihexylamine, diisopropylamine, and 4-nitrobenzenamine were described. Solvent-free conditions on alumina as solid support in the presence of $K_2CO_3$ catalysts gave moderate to good yields (55 - 93%) of diethylmalonate analogues having enamine moieties under focused microwave irradiation.

• Bulletin of the Korean Chemical Society
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• 제24권4호
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• pp.467-472
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• 2003

Optically pure α-mono- and α, α-disubstituted β-amino acids were conveniently prepared in four steps and in 27-40% overall yields from the correspondingly substituted racemic β-hydroxy acids that can be readily obtained from diethyl malonate. In the synthesis, (S)-phenylethylamine has been used as a resolving agent and as a source of the amino group in the β-amino acids.

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.857-862
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• 2006

The catalytic enantioselective Michael reaction promoted by quaternary ammonium salts from Cinchona alkaloids as a phase-transfer catalyst is described. Treatment of malonates with $\alpha$,$\beta$-unsaturated ketones under mild reaction conditions afforded the corresponding Michael adducts in good yields with good to moderate enantiomeric excesses.

• 약학회지
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• 제34권2호
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• pp.80-87
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• 1990

3-Substituted 5-aminoisoxazole-4-carboxylates were prepared by the reaction of corresponding bormoaldoximes with cyanoacetate. The 3-trifluoromethylisoxazole derivatives were acylated to amides with various aminopyridine derivatives to afford diamides. The ester group was hydrolyzed and decarboxylated easily to give 3-trifluoromethyl-5-aminoisoxazole. The aminoisoxazole was also converted to amides. 5-Amino-3-trifluoromethylisoxazole-5-one-4-carboxylate was prepared by the reaction of trifluoroacetoaldoximoyl bromide and malonate. 5-Amino-3-methylisoxazole-5-one-4-acetate was prepared by the reaction of hydroxylamine and acetylmalonate. The synthesized compounds were tested for antiinflammatory activities.

• Archives of Pharmacal Research
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• 제13권1호
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• pp.24-27
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• 1990

Reaction of 2-formyl-4H-thieno [2, 3-b] benzothiopyran-4-one (1) with different heterocyclic amines afforded the corresponding Schiff's bases (2-4). Diethyl malonate, ethyl cyanoacetate and malononitrile were reached with 1 to afford compounds 5, 7 and 8, respectively. Compound 5 was cyclized to the pyrazolidin-3, 4-dione (6) by the action of hydrazine hydrate, whereas compound 7 was utilized for the synthesis of the thiazolin-4 one derivatives (9-13).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.571-574
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• 2003

Three ring type liquid crystalline compounds having 4-alklycyclohexyl group, 1,2-difluorobenzene and phenylisothiocyanate moieties as main skeleton were designed to have negative dielectricity. However, the compounds with 2,3,2'-trifluoro-3'-isothiocyanated biphenylcyclohexane core did not exhibit the nematic liquid crystalline phase because of two conformers by interaction of isothiocyanate and adjacent fluorine atoms. Also, 4-alkyl-2,2',3'-trifluoro-3-isothiocyanated biphenylcyclohexane core was designed expecting to have uniform conformers of isothiocyanate group. In the course of developing polyimides for VA mode LCD, we synthesized alkyl-3,5-diaminobenzene efficiently with various length of alkyl chains from commercially available di-t-butyl malonate and 3,5-dinitrobenzoyl chloride as starting material.

• 대한수의학회지
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• 제30권4호
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• pp.421-425
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• 1990

The present study was conducted to investigate the biochemical and cultural characteristics of Escherichia coli isolates from clinically affected chickens during the period from May 1988 to June 1989. A total of 82 E coli cultures were isolated from lesions of 75 chickens with colisepticemia. Biochemical properties of E coli isolates tested were in accordance with the general classification standard; all the isolates showed positive reaction in Catalase, Indol, and Methyl-Red tests, but negative reaction in Oxidase, Urease, $V{\ddot{o}ges$-Proskauer, Citrate utility, $H_2S$, Phenylalanine diaminase, and malonate tests. And the carbohydrate fermentation rates of them were shown to be variable. of the 82 isolates, 48(58.5%) cultures produced colicin to inhibit the indicator strain of E coli.