• Toxicological Research
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• 제22권1호
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• pp.39-45
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• 2006

As the antioxidant and free radical scavenger, glutathione (GSH) participates in the preservation of cellular redox status and defense against reactive oxygen species and xenobiotics. Glutamate-cysteine ligase (GCL; also known as ${\gamma}$-glutamylcysteine synthetase, EC 6.3.2.2) is the rate limiting enzyme in GSH synthesis. In the present study, the accurate method for determination of GCL activity in crude liver extracts was developed by measuring both ${\gamma}$-glutamylcysteine and GSH from cysteine in the presence of glutamate, glycine and an ATP-generating system. We added glycine to promote the conversion of ${\gamma}$-glutamylcysteine to GSH, and to minimize the possibility of ${\gamma}$-glutamylcysteine metabolism to cysteine and oxoproline by ${\gamma}$-glutamylcyclotransferase. We established optimal conditions and substrate concentrations for the enzyme assay, and verified that inhibition of GCL by GSH did not interfere with this assay. Therefore, this assay of hepatic GCL under optimal conditions could provide a more accurate measurement of this enzyme activity in the crude liver extracts.

• 한국식품과학회지
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• 제27권5호
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• pp.773-775
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• 1995

The effect of alum$(Al{\cdot}K(SO_4)_2{\cdot}12H_{2}O)$ on the activity of raw starch-digesting enzyme produced by alkali-tolerant Bacillus sp. was investigated. In adding alum of 0.5%(w/w), activities of raw starch-digesting enzyme on the gelatinized and raw rice starches have not been inhibited. In case of adding alum of 5%(w/w), competitive and uncompetitive inhibition were observed for the gelatinized and raw rice starches, respectively. The inhibitory effect on the raw starch was much higher than that on the gelatinized starch.

• Archives of Pharmacal Research
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• 제16권3호
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• pp.231-236
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• 1993

Gly-224 residue of yeast alcohol dehydrogenase was mutated by site-directed mufagenesis to isoleucine, which is the corresponding amino acid residue of horse liver alcohol dehydrogenase. The mutated gene on M13 vector was subcloned in YEp13 and used to transform Saccharomyces cerevisiae 302-21 #2 strain, and the expressed protein was purified. The tumover numbers of mutant enzyme for ethanol and acetaldehyde were decreased copared to wild-type enzyme. The results of product inhibition studies indicated that the reaction mechanism was changed to Iso Theorell-Chance from Ordered Bi Bi. We supposed that Gly-224 was related to the enzyme reaction mechanism.

• Archives of Pharmacal Research
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• 제22권1호
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• pp.13-17
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• 1999

The kinetic constants and the reaction mechanism of the K228G mutant horse liver alcohol dehyrogenase isoenzyme E (HLADH-E) were compared to the wild-type enzyme. All the Km and Ki constants of the mutant enzyme for NAD+, ethanol, acetaldehyde and NADH were larger than those of the wild-type enzyme. The dissociation constants for the NADH and $NAD^{+}$ (Kiq and Kia) were greatly increased by 130-and 460-fold, respectively. The product inhibition patterns suggested that the reaction mechanism of the mutant enzyme was changed to Random Bi Bi. These results could attribute to the increase in the dissociation rate of coenzyme with the substitution at Lys-228 residue.

• 생약학회지
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• 제19권1호
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• pp.19-27
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• 1988

The hexane and ether extracts from the roots of Angelica dahurica caused a significant inhibition of hepatic drug-metabolizing enzyme (DME) activity. Through systematic fractionation by $SiO_2\;column$ and vacuum liquid chromatography monitoring by bioassays, three furanocoumarins, phellopterin, byakangelicin and tert-O-methylbyakangelicin were isolated as active principles. These components have biphasic responses, both inhibitory and inducing effects on DME system. Tert-O-methyl byakangelicin was found to have the strongest enzyme inhibitory potency.

• Bulletin of the Korean Chemical Society
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• 제17권11호
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• pp.1018-1022
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• 1996

Adenosine deaminase (ADA) has been utilized as the label in devising a potentiometric homogeneous assay for riboflavin and riboflavin binding protein (RBP). The proposed homogeneous assay method employs an ADA-biotin conjugate as the signal generator and an avidin-riboflavin conjugate as the signal modulator in the solution phase. The catalytic activity of the ADA-biotin conjugate is inhibited in the presence of an excess amount of the avidin-riboflavin conjugate, and the observed inhibition is reversed in an amount proportional to the concentration of RBP added. When the analyte riboflavin is added to this mixture of ADA-biotin, avidin-riboflavin and RBP, the activity of the enzyme conjugate is re-inhibited in an amount proportional to the concentration of riboflavin. Since the enzyme label used in this system is ADA, an ammonia-producing enzyme, a potentiometric rather than photometric detection scheme is used to monitor the enzymatic activity in the assay.

• Archives of Pharmacal Research
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• 제11권2호
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• pp.122-126
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• 1988

The effects of psoralen and angelicin on hepatic microsomal drug-metabolizing enzyme (DME) activities were investigated to elucidate the mode of the interaction of furanocoumarins with DME system. A single administration (30 mg/kg,i. p.) of both coumarins to mice cased a significant prolonagation of hexobarbital-induced hypnosis as well as an increase in strychnine toxicity. The inhibitory potencies of both coumarins as measured by rat hepatic microsomal aminopyrine N-demethylase and hexobarbital hydroxylase activities in vitro were considerably weaker than those of other furanocoumarins which possess a side chain moiety. Both coumarins were found to have significant inducing effects of DME system, with repeated treatments of them. The activities of an angular coumarin were stronger than those of a linear coumarin.

• 대한약리학회지
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• 제26권2호
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• pp.219-226
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• 1990

국내 생산 enalapril maleate 10mg 제제 $(Beartec^{\circledR})$의 생물학적 동등성을 검토키위해, 원 제조원인 Merck사의 $Vasotec^{\circledR}$을 기준 제제로하여 12명의 건강한 남성지원자를 대상으로 10mg 1회 경구 투여 교차시험후 약동학적 성상, ACE활성억제의 경시적 변화 및 혈압 변동을 검토한 결과는 다음과 같다. 1. 혈장 enalapril 및 활성형 대사물인 enalaprilat의 생체이용율 지표들(AUC, Tmax 및 Cmax)의 평균치는 시험제제에서 enalapril의 최고 혈장농도 도달시간(Tmax)이 약 27%(0.21시간)지연되었을 뿐 타 지포는 대조제제에 대한 백분율 차이에 있어 ${\pm}20%$내외였다. 2. 혈장 enalapril및 enalaprilat의 생체 이용율 지표들은 분산 분석에 의해 두 제제간에 차이를 인지할 수 없었다. 3. 시험제제의 생체이용율 지표들은, 대조제제에 대한 백분율을 95% 신뢰구간 검정시, enalapril의 AUC 및 Tmax를 제외한 enalapril 및 enalaprilat의 모든 지표는 ${\pm}20%$ 내외의 결과를 보였다. 4. 두제제 투여후 ACE활성도는 enalaprilat 혈장농도 5-6ng/ml에서 50%의 억제를 보였으며, 투약 23시간까지의 활성억제 AUC는 차이가 없었다. 5. 두 제제 투여후 수축기 및 이완기 혈압은 투약 2시간 이후 유의한 감소를 보였으며 혈압 변동은 두제제간에 차이를 인지할 수 없었다. 이상의 실험 결과로 enalapril maleate의 국내 생산 generic product는 기준제제인 $Vasotec^{\circledR}$과 동등한 생물학적 동등성을 지니며 치료적 등가성을 보이는 제제로 판단하였다.

• Food Science and Biotechnology
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• 제17권4호
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• pp.873-877
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• 2008

Native soy protein isolate (SPI) was hydrolyzed with 4 different proteolytic enzymes, including bromelain, papain, Neutrase, and Flavourzyme. SPI hydrolysates with the degree of hydrolysis (DH) in range of 6 to 15% were prepared by each enzyme. The angiotensin 1 converting enzyme (ACE) inhibitory and the antioxidant activities of the SPI hydrolysates, such as superoxide dismutase-like activity and inhibition of the linoleic acid autoxidation, were evaluated. Overall, as the DH increased, all evaluated bioactivities of the SPI hydrolysates significantly increased. The significantly highest ACE inhibitory and antioxidant activities were found in hydrolysates made with papain and bromelain, respectively. SPI hydrolysates by Flavourzyme showed the significantly lowest activity in all tested bioactivities. The results suggested that ACE inhibitory and antioxidant activities of SPI hydrolysates were determined by the DH and by the enzyme used.

• Bulletin of the Korean Chemical Society
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• 제1권1호
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• pp.10-17
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• 1980

Penicillin amidohydrolase was partially purified from the fermented broth of Bacillus megaterium, and was immobilized on nylon fiber. The surface area of nylon fiber was increased by roughening it with fine sand and activated by acid treatment. The free amino groups on the nylon fiber exposed by such treatment were then utilized to immobilize the penicillin amidase. Enzymatic properties of penicillin amidohydrolase immobilized on the nylon fiber by covalent bonding and cross linking with glutaraldehyde were studied and compared with those of soluble enzyme. The optimal pH and temperature profile of immobilized enzyme showed only slightly broader peaks, and the values of kinetic constants, $K_m$, $K_{ia}$, and $K_{ip}$, of the immobilized enzyme are only slightly greater than those of the soluble enzyme. These results suggest that the mass transfer effect on the reaction rate for the penicillin amidase immobilized on nylon fiber is not so significant as the enzyme immobilized on some other support material like bentonite. The experimental results of batch reaction agreed well with the results of computer simulation for both the immobilized and soluble enzyme systems, confirming the validity of the rate equation derived which was based on the combined double inhibition by two reaction products.