• Title/Summary/Keyword: non-competitive inhibition

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Some Kinetic Properties of an Extracellular Chitinase from Streptomyces sp, 115-5 (Streptomyces속 115-5 균주로부터 생성된 Chitinase의 저해작용기작)

  • Hong, Yong-Ki;Seu, Jung-Hwn
    • Microbiology and Biotechnology Letters
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    • v.9 no.4
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    • pp.179-183
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    • 1981
  • An extracellular chitinase was purified from the culture fluid of Streptomyces sp. 115-5, and its inhibition mechanism by end product was studied. The activity of chitinase was suppressed by the reducing sugar as the reaction proceeded, and the activity was inhibited by the addition of D-glucose. Besides D-glucose, the rate of chitin hydrolysis was inhibited by D-glucuronic acid, D-sorbitol and D-xylose in the reaction system of the enzyme. it was found that the hydroxyl groups at the C-2, C-3 and C-4 position of D-glucose molecule play an important role in the inhibition of the chitinase activity. D-glucose was found to inhibit the enzyme activity by mixed type of competitive and non-competitive mode.

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Effect of pyroligneous acids on urease inhibition (요소분해 저해에 미치는 목초액의 영향 평가)

  • Park, Hyun Jun;Park, Jin Hee
    • Journal of Applied Biological Chemistry
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    • v.60 no.2
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    • pp.173-178
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    • 2017
  • This study was conducted to investigate the effect of pyroligneous acids on urea hydrolysis for the purpose of inhibiting ammonia volatilization during urea fertilizer application. Different types of synthetic urease inhibitors have been searched and developed, but their use is limited due to varying inhibition effects on soil urease, and environmental problems. In this study, the effect of pyroligneous acids, a natural substance, on urea hydrolysis in soil was evaluated by analyzing inhibition of urease activity. Pyroligneous acids inhibited plant urease and microbial urease activity, as well as soil urease with various urease complex. In addition, pyroligneous acids exhibited non-competitive urease inhibition effect through urease kinetics and inhibited urea hydrolysis in the soil. This study showed that pyroligneous acids treatment with urea fertilizer decreases the loss of urea fertilizer, improves the efficiency of nitrogen application on plant and reduces the amount of nitrogen fertilizers applied in soil.

Inhibition of Thymidylate Synthase by Non-Steroidal Anti-Inflammatory Drugs

  • Cho, Sung-Woo;Park, Soo-Young;Kim, Tae ue
    • Biomolecules & Therapeutics
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    • v.3 no.1
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    • pp.34-37
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    • 1995
  • Non-steroidal anti-inflammatory drugs (NSAIDs) have been known as inhibitors of the folate-requiring enzymes. In the present work, we have expanded on these observations and have investigated the inhibitory effects of NSAIDs on Lactobacillus casei thymidylate synthase expressed in E. coli. NSAIDs including sulphasalizine, salicylic acid, indomethacin and mefenamic acid were found to be competitive inhibitors with respect to folate of Lactobacillus casei thymidylate synthase. In contrast, aspirin and the antipyretic-analgesic drugs acetaminophen and antipyrine were weak inhibitors of the enzyme. Structure-activity correlation suggests that an aromatic ring with a side chain containing a carboxylic acid is a requirement for competitive inhibition of the thymidylate synthase. The results are consistent with the hypothesis that the antifolate activity of NSAIDs, and hence cytostatic consequences, are important factors in producing anti-inflammatory activity and aspirin exerts its anti-inflammatory effects after its conversion into salicylic acid, which possesses greater antifolate activity than its parent compound.

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Inhibition of hepatic microsomal drug-metabolizing enzymes by imperatorin

  • Shin, Kuk-Hyun;Woo, Won-Sick
    • Archives of Pharmacal Research
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    • v.9 no.2
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    • pp.81-86
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    • 1986
  • The effect of imperatorin on hepatic microsomal mixed function oxidases (MF0) was investigated. On acute treatment, imperatorin (30 mg/kg, i.p) caused a significant reduction in activities of hepatic aminopyrine N-demethylase, hexobarbital hydroxylase and aniline hydroxylase as well as cytochrome p0450 content in rats and mice. Kinetic studies on rat liver enzymes revealed that imperatorin appeared to be a competitive inhibitor of aminopyrine N-demethylase (Ki,0.007 mM), whereas a non-competitive inhibitor of hexobarbital hydroxylase (Ki, 0.0148 mM). Imperatorin also inhibited non-competitively aniline metabolism (Ki 0.2 mM). Imperatorin binds to phenobarbital-induced cytochrome p-450 to give a typical type 1 binding sepctrum (max. 388nm, min 422 nm). Multiple administrations of imperatorin (30 mg/kg. i. p. daily for 7 days) to mice shortended markedly the duration of hexobarbital narcosis and increased activities of hepatic aminopyrine N-demethylase and hexobarbital hydroxylase and the level of cytochrome p-450 where as aniline hydroxylase activity was unaffected.

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Hydrophobic Interaction Between the Acyl Moiety of Choline Esters and the Active Site of Acetylcholinesterase

  • Myung, Pyung-Keun;Sok, Dai-Eun
    • BMB Reports
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    • v.28 no.4
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    • pp.290-292
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    • 1995
  • Existence of a binding site for choline esters with an acyl chain of various sizes was examined by comparing the inhibitory potency of the respective compound. In contrast to acetylcholine, which showed a pure competitive pattern of inhibition, choline esters with an acyl chain of a long size ($C{\geq}5$) expressed a mixed type of inhibition. Binding of choline esters containing a long chain ($C_7-C_{12}$) to the hydrophobic region in the active site is deduced from a linear relationship between the $K_{iE}$ value and the size of acyl moiety, and a good hydrophobicity relationship. In addition, the non-competitive component in the inhibition of acetylcholinesterase seems to be due to the interaction of choline esters with both the hydrophobic site and the trimethylammonium-binding site in the active center of the acetylated acetylcholinesterase.

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Inhibition of Monoamine Oxidase by Evodiamine (Evodiamine의 Monoamine Oxidase 활성 저해작용)

  • Lee, Sang-Seon;Hwang, Bang-Yeon;Ro, Jai-Seup;Lee, Myung-Koo
    • Korean Journal of Pharmacognosy
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    • v.37 no.4 s.147
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    • pp.320-323
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    • 2006
  • The effects of evodiamine on monoamine oxidase (MAO) activity were investigated. MAO was purified from mouse brain and the $K_m\;and\;V_{max}$ values of MAO were $78.5{\pm}5.28{\mu}M$ and $0.68{\pm}0.07$ nmol/min/mg protein, respectively (n=4). Evodiamine at $30-120{\mu}M$ showed an inhibitory effect on MAO activity using a substrate kynuramine with an $IC_{50}$ value of $104.2{\mu}M$ (n=4). Evodiamine also exhibited a non-competitive inhibition on MAO. The $K_i$ value for evodiamine was $72.5{\pm}10.8{\mu}M$ (n=4). These results suggest that evodiamine partially contributes to the regulation of monoamine content.

Trypsin Inhibitor from Streptomyces sp. (Part 2) Biological Activities or the Inhibitor (Streptomyces 속 균주가 생성하는 Trypsin Inhibitor (제2보) 저해물질의 생물학적 작용상)

  • Yi, Dong-Heui;Seu, Jung-Hwn
    • Microbiology and Biotechnology Letters
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    • v.10 no.4
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    • pp.283-288
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    • 1982
  • Trypsin inhibitor produced by Streptomyces sp. was investigated its reactive characteristics against trypsin. The mode of inhibition against trypsin was mixed type of non-competitive and competitive with casein, and enzyme-inhibitor complex was formed rapidly. The inhibitory activity was increased by the addition of isoleucine and depressed by silver, mercuric or cupric ion. And when egg albumin or hemoglobin was used as substrate for trypsin, the inhibition ratio was changed. The inhibitor inhibited coagulation of blood of bovine.

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Inhibitory Effects of Proanthocyanidin Extracted from Distylium racemosum on ${\alpha}-Amylase$ and ${\alpha}-Glucosidase$ Activities (조록나무 Proanthocyanidin의 ${\alpha}-Amylase$${\alpha}-Glucosidase$에 대한 저해 효과)

  • Ahn, Jin-Kwon;Park, Young-Ki;Park, So-Young;Kim, Yong-Mu;Rhee, Hae-Ik;Lee, Wi-Young
    • Korean Journal of Pharmacognosy
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    • v.35 no.4 s.139
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    • pp.271-275
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    • 2004
  • Distylium racemosum Sieb. Et Zucc contains some compounds inhibit -amylase activity in experimental conditions. The inhibitory test showed that 50% acetone extracts from the bark and leaves of the plant strongly inhibited salivary -amylase activity. Proanthocyanidin(PA) which has strong inhibitory activity was extracted from the leaves by chromatography on Sephadex LH-20. The inhibitory activities and the inhibition kinetics of the PA were studied against three kinds of enzymes: human salivary ${\alpha}-Amylase$ (SAA), pork pancreatin ${\alpha}-Amylase$ (PAA) and yeast ${\alpha}-Glucosidase$ (AG). Then the activities of PA against SAA, PAA and AG were compared with those of acarbose, a commercial agent. The inhibitory activities of PA were stronger than those of acarbose. Inhibition kinetics of the PA showed competitive inhibition for SAA and PAA, and non competitive inhibition for GA.

Effects of Ethanol on Na-K-ATPase Activity of Cat Kidney (Ethanol 이 고양이 신장 Na-K-ATPase 활성에 미치는 영향)

  • Kim, Joo-Heon;Kim, Yong-Keun
    • Korean Journal of Veterinary Research
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    • v.23 no.1
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    • pp.9-16
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    • 1983
  • The effects of ethanol on Na-K-ATPase activity were investigated with cat kidney homogenate. The results were summarized as follows: 1. Na-K-ATPase activity was inhibited with dose-dependent manner by ethanol of higher concentration than 1%, and showed an estimated $I_{50}$ (the inhibitor concentration to cause 50% inhibition) of 7.5%. 2. Hydrolysis of ATP was linear with the incubation time in the absence and presence of 8% ethanol, whereas it was different with preincubation time in the presence of 15% ethanol. 3. Inhibition of Na-K-ATPase activity by ethanol was not affected by increased enzyme concentration, and showed the reversibility of the inhibitory pattern. 4. Kinetic studies of cationic-substrate activation of Na-K-ATPase showed that ethanol had both properties of classical competitive inhibition for $Mg^{{+}{+}}$ or $K^+ and non-competitive inhibition for ATP or $Na^+$. 5. Arrhenius plot yield two break point at $21^{\circ}$ and $30^{\circ}C$ in the absence of ethanol, whereas showing only one break point at $18^{\circ}C$ in the presence of 8% ethanol. These results suggested that ethanol inhibited Na-K-ATPase activity reversible through a disturbance of microenvironment of lipids associated with the enzyme.

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Mechanism of Inhibition of Human Cytochrome P450 1A1 and 1B1 by Piceatannol

  • Chae, Ah-Reum;Shim, Jae-Ho;Chun, Young-Jin
    • Biomolecules & Therapeutics
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    • v.16 no.4
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    • pp.336-342
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    • 2008
  • The resveratrol analogue piceatannol (3,5,3',4'-tetrahydroxy-trans-stilbene) is a polyphenol present in grapes and wine and reported to have anti-carcinogenic activities. To investigate the mechanism of anticarcinogenic activities of piceatannol, the effects on CYP 1 enzymes were determined in Escherichia coli membranes coexpressing recombinant human CYP1A1, CYP1A2 or CYP1B1 with human NADPH-P450 reductase. Piceatannol showed a strong inhibition of CYP1A1 and CYP1B1 in a concentration-dependent manner, and $IC_{50}$ of human CYP1A1 and CYP1B1 was 5.8 ${\mu}M$ and 16.6 ${\mu}M$, respectively. However, piceatannol did not inhibit CYP1A2 activity in the concentration of up to 100 ${\mu}M$. Piceatannol exhibited 3-fold selectivity for CYP1B1 over CYP1A1. The mode of inhibition of piceatannol was non-competitive for CYP1A1 and CYP1B1. The result that piceatannol did not inhibit CYP1B1-mediated $\alpha$-naphthoflavone ($\alpha$-NF) metabolism suggests piceatannol may act as a non-competitive inhibitor as well. In human prostate carcinoma PC-3 cells, piceatannol induces apoptosis and prevents Aktmediated signal pathway. Taken together, abilities of piceatannol to induce apoptotic cell death as well as CYP1 enzyme inhibition make this compound a useful tool for cancer chemoprevention.