• Bulletin of the Korean Chemical Society
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• 제6권5호
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• pp.312-317
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• 1985

${\beta}$-Glucuronidase (EC 3.2.1.31) which hydrolizes D-glucuronate from ${\beta}$-D-glucuronide was purified from rat liver, using ammonium sulfate fractionation, DEAE-cellulose chromatography, Concanavalin-A Sepharose 4B chromatography and gel filtration on Sephadex G-200. This enzyme has the molecular weight of 280,000 daltons by gel filtration and 75,000 daltons by SDS-polyacrylamide gel electrophoresis. As its funtion is reverse of detoxification in the liver, the inhibition of the enzyme was tested with extracts of several food products and medicinal herbs, some are known as anti-cancer agents. Among them, Panax ginseng and Cortnellus shiiake inhibited the enzyme competitively and the $K_1$ values were $9.22 {\times}\;10^{-2}$ and 0.102 mg/ml, respectively. These inhibitors strongly bound to DEAE-cellulose. The negatively charged amino acids, L-aspartate and L-glutamate, inhibited the enzyme, and $K_1$ value of L-aspartate was 0.80 mM. The interaction between ${\beta}$-glucuronidase and p-nitrophenyl-${\beta}$-D-glucuronide was found to involve ionic forces by the effect of ionic strength on the kinetic constant, Vmax/Km. It was inferred from these findings that cationic group at the active center of the enzyme is probably involved in attacking the substrate.

• 대한한의학회지
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• 제16권1호통권29호
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• pp.281-294
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• 1995

The effect of Sam Hwa San on the Na-K-ATPase activity was evaluated in microsomal fraction prepared from rabbit cerebral cortex to determine whether Sam Hwa San affects Na-K-ATPase activity of nervous system. Sam Hwa San markedly inhibited the Na-K-ATPase activity in a dose-dependent manner with an estimated $I_{50}$ of 0.12%. Optimal pH for the Na-K-ATPase activity was at 7.5 in the presence or absence of Sam Hwa San. The degree of inhibition by the drug more increased at acidic and alkalic pHs than neutral pH. Kinetic studies of substrate and cationic activation of the enzyme indicate classic noncompetitive inhibition fashion for ATP, Na and K, showing significant reduction in Vmax without a change in Km. Dithiothreitol, a sulfhydryl reducing reagent, partially protects the inhibition of Na-K-ATPase activity by Sam Hwa San. Combination of Sam Hwa San and ouabain showed higher inhibition than cumulative inhibition. These results suggest that Sam Hwa San inhibits Na-K-ATPase activity in central nervous system by reacting with, at least a part, sulfhydryl group and ouabain binding site of the enzyme protein, but with different binding site from those of ATP, Na and K.

• Asian-Australasian Journal of Animal Sciences
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• 제14권9호
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• pp.1216-1220
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• 2001

Effect of hydroquinone (HQ) on rumen urease activity was studied. Hydroquinone at concentrations of 0.01 ppm, 0.1 ppm, 1 ppm, and 10 ppm inhibited urease activity of intact rumen microbes in vitro by 25%, 34%, 55% and 64% respectively. In the presence of low concentrations of $\beta$-mercaptoethanol, rumen urease could be solubilized and partially purified. The Km for the enzyme was $2{\times}10^{-3}$ M with Vmax of $319.4{\mu}moles/mg$ min. The kinetics of inhibition with partially purified rumen urease was investigated. The result showed that the inhibitory effect was not eliminated by increasing urea concentrations indicating a noncompetitive effect in nature with an inhibition constant $1.2{\times}10^{-5}$ M. Hydroquinone at the concentration of 10 ppm produced 64% urease inhibition, did not affect ruminal total dehydrogenase and proteolytic enzyme (p>0.05), but increased cellulase activity by 28% (p<0.05) in vitro. These results indicated that hydroquinone was a effective inhibitor of rumen urease and could effectively delay urea hydrolysis without a negative effect. The inhibitor appeared to offer a potential to improve nitrogen utilization by ruminants fed diets containing urea.

• 한국연초학회지
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• 제9권2호
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• pp.69-75
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• 1987

Nicotine, the main alkaloid of tobacco, showed different effect according to the enzyme. Among investigated enzymes, protease was inactivated remarkably by nicotine and the mode of inhibition was examined. $\alpha$-amylase and $\beta$-amylase were not affected, and cellulase and glucoamylase were inactivated partially when the concentration of it was over 1.0% , but protease was inhibited powerfully by nicotine The inhibition of protease by nicotine was performed almost in the initial stage of reaction, and was not so much affected by temperature, and was reversible. The inhibition type of protease by nicotine appeared as a Mixed-type inhibition.

• Journal of Microbiology and Biotechnology
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• 제9권4호
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• pp.414-421
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• 1999

Helicobacter pylori were found to be resistant to azide but sensitive to vanadate, suggesting that defect in the P-type ATPase activity rather than F-type ATPase would be lethal to cell survival or growth. To elucidate the relationship between this enzyme inhibition and H. pylori death, we determined the effect of omeprazole (OMP) plus vanadate on enzyme activity and cell growth. The minimum inhibitory concentration (MIC; ca. 0.8$\mu$mol/disk) of vanadate for H. pylori growth was lowered over l0-fold with the aid of OMP, whereby its inhibitory potential toward the P-type ATPase activity was diametrically increased. Alternatively, we found that this enzyme activity was essential for active transport in H. pylori. From these observations, we strongly suggest that the immediate cause of the growth inhibition of H. pylori cells with OMP and/or vanadate might be defective in the cell's active transport due to the lack of P-type ATPase activity. From the spectral data with circular dichroism (CD) spectroscopy, we found that activated OMP (OAS) at concentration below MIC did not disrupt helical structures of membrane proteins. Separately, we determined the cytopathic effect of OAS by SDS-PAGE, indicating the change in the production of cytoplasmic protein but not cell membrane.

• 대한한의학회지
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• 제22권2호
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• pp.3-9
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• 2001

국내에서 많이 사용되는 한약재 51종을 극성에 따라 4가지 용매로 분획한 후 안지오텐신 전환 요소 활성도 억제를 검색한 결과 다음과 같은 결과를 얻었다. 1. 202종의 분획중 $400{\;}\mu\textrm{g}/ml$의 농도에서 안지오텐신 전환효소 활성도를 50% 이상 억제한 추출물 수는 26종이었고, 90% 이상 억제한 추출물 수는 4종이었다. 2. 대부분 추출물의 $IC_{50}$ 수치는 $300-400{\;}\mu\textrm{g}/ml$ 이었으나 택사의 물층, 황련의 buthanol, 물 추출물과 단삼의 ethylacetate, buthanol 추출물, 토사자의 ethylacetate 추출물 등은 6종의 추출물은 $200{\;}\mu\textrm{g}/ml$ 이하의 $IC_{50}$을 보였다. 이상과 같은 결과로 보아 많은 한약재들의 항고혈압 효과는 부분적으로 안지오텐신 전환효소를 억제하는 효과에 의한 것으로 여겨진다.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.152-158
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• 2016

글루탐산염(Glutamate)은 척추동물의 중추신경계에서 중요한 흥분성 신경전달물질 중의 하나이다. 글루탐산염의 대사를 조절하는 사람 글루탐산염 탈수소 효소(hGDH)는 정신분열증(schizophrenia) 환자의 대뇌에서 발현이 증가한다는 연구들이 있었다. 본 연구에서는 정신분열증과 연관된 항정신성약물인 haloperidol, risperidone, (${\pm}$)-sulpride, chlopromazine hydrochloride, melperone, (${\pm}$)butaclamol, domperidone, clozapine에 의한 hGDH의 효소활성변화를 확인하고자 하였다. 우선, 유전자 재조합을 통해 hGDH 동종효소 hGDH1, hGDH2를 합성하였다. 합성된 hGDH1과 hGDH2에 대한 항정신성약물의 억제효과를 효소검사법(enzyme assay)을 통해 확인한 결과, haloperidol, (${\pm}$)-sulpride, melperone, clozapine에 의해 hGDH1과 hGDH2의 효소활성이 억제되었다. 또한, 단백질 인산화 효소 측정법(kinase assay)을 하여 haloperidol이 기질인 알파-케토글루타르산에 대하여는 비경쟁적 저해반응(noncompetitive inhibition)을, NADH에 대하여서는 반경쟁적 저해반응(uncompetitive inhibition)이 나타는 것을 확인하였다. 입체성 다른 자리 작동체(allosteric effector)인 L-leucine이 다른 정신병치료제에서는 hGDH2의 억제를 회복시켰지만 오직 haloperidol에서는 효소의 활성이 회복되지 않았다. 따라서 본 연구는 hGDH1과 hGDH2 에서 항정신성약물에 의한 효소활성 억제를 비교하여 확인하였으며, 중추신경계에서 haloperidol이 GDH 활성 조절과 함께 글루탐산 농도를 조절할 수 있다는 가능성을 제시한다.

• 한국미생물·생명공학회지
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• 제13권3호
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• pp.173-178
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• 1985

Ganoderma lucidum (영지)의 액체 배양물로부터 전분을 강력하게 분해하는 amylase를 조정제하여 이 효소의 기본적인 성질을 조사하였다. 이 효소의 최적작용 pH와 온도는 각각 5.5, 5$0^{\circ}C$였고 pH 및 열처리에 상당히 불안정한 효소였으며 activation energy는 7.06Kcal/mole이였다. M $n^{++}$, $Ca^{++}$ 및 C $u^{++}$에 의해서 효소활성이 증가되었으나 H $g^{++}$ A $g^{+}$에 의해서 효소활성이 저해되었으며 여러 가지 chemical reagents에 의해서는 영향을 받지 않았다. Soluble starch, amylose, amylopectin 및 glycogen에 대한 Km 치는 0.16, 0.37, 0.19 및 0.16mg/$m\ell$ 였으며 각종기질에 대한 분해능력을 조사한 결과 열처리를 받은 전분류는 분해할 수 있었으나 생전분은 그 분해속도가 느렸다. Maltose에 의해서 효소활성이 저해되었으며 maltose의 저해양상은 competitive inhibition을 나타내었다.

• BMB Reports
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• 제31권3호
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• pp.296-302
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• 1998

A potentiometric flow injection biosensor for the analysis of anti-cholinesterases (anti-ChEs), based on inhibition of enzyme activity, was developed. The sensor system consists of a reactor with acetylcholinesterase (AChE) immobilized on controlled pore glass and a detector with an $H^{+}-selective$ PVC-based membrane electrode. The principle of the analysis is based on the fact that the degree of inhibition of AChE by an anti-ChE is dependent on the concentration of the anti-ChE in contact with AChE. The sensor system was optimized by changing systematically the operating parameters of the sensor to evaluate the effect of the changes on sensor response to ACh. The optimized biosensor was applied to the analysis of paraoxon, an organophosphorus pesticide. Treatment of the inhibited enzyme with pyridine-2-aldoxime fully restored the enzyme activity allowing repeated use of the sensor.

• 한국식물병리학회지
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• 제10권2호
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• pp.119-122
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• 1994

Effects of organophosphorus fungicides on cutinase activity from Glomerella cingulata causing apple anthracnose and infection of apple were investigated. Diisoprophylfluorophosphate (DFP) inhibited the enzyme activity indicating that catalysis involves an active serine. In inhibition of the enzyme activity by organophosphorus fungicides, I50 (molar concentration of fungicide at which the enzyme activity is inhibited 50%) of Hinosan and Kitazin P were 26.3 $\mu$M and 427.7 $\mu$M, respectively. At concentration of 10-3 M DFP and organophosphorus fungicides, the infection of G. cingulata was inhibited to 5% in comparison with 15% infection at the unwounded healthy control, but increased to 30% when added with 1 mg/ml of cutinase. Mycelial growth was 36 mm in colony diameter on the medium added with 10-4M of hinosan in comparison with 90 mm of the untreated control, but was 90 mm on the medium added with 10-4M of kitazin P showing lower inhibition than hinosan. The spore germination was more than 60% at all the concentrations of both fungicides.