• Journal of Photoscience
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• 제9권2호
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• pp.118-121
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• 2002

A state of bacteriorhodopsin at high temperature was studied by various spectral measurements. The stability measurements indicated that the onset temperature of the denaturation was 70$^{\circ}C$ in the dark and 60$^{\circ}C$ under illumination. The reactivity of hydroxylamine with the Schiff's base also significantly increased in the temperature range between 60 and 70$^{\circ}C$. A spectral band at about 470 nm appeared in the temperature range higher than 60$^{\circ}C$. The circular dichroism spectra in the visible region started to change from a bilobed exiton type to a positive band at about 60$^{\circ}C$, suggesting that the two-dimensional configuration of bacteriorhodopsin molecules changed from crystalline to amorphous. All the measurements suggested a new state between 60 and 70$^{\circ}C$ in which bacteriorhodopsin is stable only in the dark.

• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.719-728
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• 2005

A novel 2-amino-4-(8-quinolinol-5-yl)-1- (p-tolyl)-pyrrole-3-cabonitrile (2) was obtained by the reaction of 2-[2-bromo-1-(8-hydroxyquinolin-5-yl)-ethylidene]-malononitrile (1) with p-toluidene. The new synthon compound (2) could be annelated to the corresponding pyrrolo[2,3-d]pyrimidines (4, 6, 7, 26-28), triazolo[1,5-c]pyrrolo[3,2-e]pyrimidines (10, 29, 30), pyrrolo[2,3-c]pyrazoles (11-15), pyrrolo[1,2-a]pyrrolo[3,2-e] pyrimidine (17) and imidazo[1,2-c]pyrrolo[3,2-e]pyrimidines (18-25) via the reaction with some reagents such as acetic anhydride, formamide, triethyl orthoformate, hydrazine hydrate, hydroxylamine, ethylenediamine, carbon disulfide and phosphorus oxychloride. Chemical and spectroscopic evidences for the structures of these compounds are presented. The antifungal and antibacterial activity of the newly synthesized comounds were evaluated.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.213-215
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• 2004

An indirect, sensitive and accurate method for the determination of trace amounts of hydrazine is described. The method is based on the oxidation of hydrazine by a known excess of iodate in the presence of hydrochloric acid. The unreacted iodate is used in the oxidation of hydroxylamine to nitrite. Sulfanilic acid is diazotized by the nitrite formed. The resulting diazonium ion is coupled with N-(1-naphthyl)ethylenediamine to form a stable azo dye, which shows an absorption maximum at 540 nm. Hydrazine can be determined in the range of 20-400 ng $mL^{-1}$ with a detection limit of 3.1 ng $mL^{-1}$. The relative standard deviation for 50, 200 and 400 ng $mL^{-1}$ of hydrazine is 2, 1.5 and 1.3%, respectively (n = 10). The method was applied to the determination of hydrazine in water samples.

• Environmental Analysis Health and Toxicology
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• 제17권2호
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• pp.117-123
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• 2002

A gas chromatographic method for the determination of airborne formaldehyde was established. In order to be highly detectable with the electron capture detector, formaldehyde was derivatized to its pentafluorobenzyl oxime form by reacting with O- (2,3,4,5,6- pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) at pH of 4.6 and temperature of 50$^{\circ}C$ for 1 hour. Air samples were collected into a Tedlar$\^$(R)/ bag followed by transferring into water contained in two impingers in series. Collection efficiency in the front trap was higher than 90％. Measurement of selected indoor and outdoor air samples showed higher formaldehyde concentrations in indoor air environments and the importance of ventilation for reducing indoor pollution.

• 한국환경과학회지
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• 제8권3호
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• pp.371-377
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• 1999

The effects of benzamidoxime concentration, solvents and temperature on the degree of metal extraction were investigated to apply benzamidoxime to heavy metal extraction as chelating agent. Benzamidoxime was synthesized from benzonitrile with hydroxylamine. The chemical structure of benzamidoxime was identified. The degree of heavy metal extraction was increased with increasing the concentration of benzamidoxime and decreasing the extraction temperature. Benzamidoxime was found to be an concentration of benzamidoxime and decreasing the extraction temperature. Benzamidoxime was found to be an effective extractant for Cu-extraction by benzene or chloroform. The relationship between the thermodynamic overall equilibrium constant and absolute temperature was expressed as log K = -5.56 ＋ $855T^{-1}$. Heat of extraction, $$\Delta$H^0$ were calculated from overall equilibrium constants at various temperature and the extraction reactionby benzamidoxime was found to be exthothermic.

• Journal of Microbiology and Biotechnology
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• 제4권3호
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• pp.176-182
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• 1994

The light-organ symbiont of pine cone fish, Vibrio fischeri, senses its presence in the host and responds to environmental changes by differentially expressing its symbiosis-related luminescence genes. The V. fischeri luminescence genes are activated by LuxR protein in the presence of an autoinducer. In an effort to elucidate the mechanism of regulation of luxR, a plasmid containing luxR was mutagenized in vitro with hydroxylamine and a luxR mutant plasmid was isolated by its ability to activate luminescence genes cloned in E. coli in the absence of the autoinducer. The specific base change identified by DNA sequencing was only single base transition at ＋78 from the transcriptional start of luxR. Based on a Western immunoblot analysis, the nucleotide change directed the synthesis of much higher level of LuxR protein without any amino acid substitutions. The results suggest that the region including the ＋78th base is presumably internal operator required for autorepression of luxR, and the increased cellular level of LuxR results in activation of luminescence genes by autoinducer independent fashion.

• Archives of Pharmacal Research
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• 제27권9호
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• pp.885-892
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• 2004

Due to the rapidly growing number of resistant strains of bacteria, the search for antibacterial agents with new modes of action will always remain an important and challenging task. Thus, the reaction of 2-substituted or. unsubstituted-4-(4-acetylanilino)-5,6,7,8-terahydrobenzo［b］ thieno［2,3-d］pyrimidine derivatives 1-3 with the hydrazine derivatives, semi and / or thiosemi-carbazides, provided the corresponding hydrazones 4-6 and semi and/or thiosemicarbazones 7-9. Claisen-Schmidt condensation of compounds 1 or 2 with the appropriate aldehyde yielded the chalcones 10, 11 which, when treated with hydroxylamine hydrochloride gave rise to the isoxazoline-containing compounds 12, 13. Furthermore, reacting the respective chalcones 10, 11 with different hydrazines, urea and/or thiourea, furnished compounds 14, 15, 16, and 17 respectively. Representative compounds were tested for their antimicrobial activity against Candida Albicans and certain gram-positive and gram-negative bacteria. Their MICs were then determined. Compound 15e, showed a broad spectrum of activity while most of the other com-pounds showed varying antimicrobial activity.

• 대한화학회지
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• 제9권1호
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• pp.41-44
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• 1965

7-Nitroso-8-hydroxyquinoline-5-sulfonate의 Fe(II)錯鹽의 性質을 700$m{\mu}$, $26^{\circ}C$에서 分光光度法으로 調査하였다. 이 錯鹽은 pH6.0에서 가장 큰 吸光度를 나타내며 熱安定度도 대단히 좋다. Ligand나 Fe(III)의 還元에 使用한 hydroxylamine이 過剩으로 存在할때 에도 錯鹽의 生成에 影響을 주지 않는다. 錯鹽의 組成을 몰比法과 連續變化法으로 調査한 結果, 金屬과 ligand의 몰比는 1:3이였다. 檢量線은 實驗한 濃度範圍內에서 Beer의 法則에 따른다.

• 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.

• Toxicological Research
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• 제23권3호
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• pp.189-196
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• 2007

Cytochrome P450 (P450) enzymes are the major catalysts involved in the biotransformation of various drugs, pollutants, carcinogens, and many endogenous compounds. Most of chemical carcinogens are not active by themselves but they require metabolic activation. P450 isozymes playa pivotal role in the metabolic activation. The activation of arylamines and heterocyclic arylamines (HAAs) involves critical N-hydroxylation, usually by P450. CYP1A2 plays an important role in these reactions. Broad exposure to many of these compounds might cause carcinogenicity in animals and humans. On the other hand, P450s can be also involved in the bioactivation of other chemicals including alcohols, aflatoxin B1, acetaminophen, and trichloroethylene, both in humans and in experimental animals. Understanding the P450 metabolic activation of many chemicals is necessary to develop rational strategies for prevention of their toxicities in human health. An important part is the issues of extrapolation between species in predicting risks and variation of P450 enzyme activities in humans.