• Title, Summary, Keyword: inhibitor binding

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Inactivation of Brain Glutamate Dehydrogenase Isoproteins by MDL 29951

  • Lee, Eun-Young;Yoon, Hye-Young;Kim, Tae-Ue;Choi, Soo-Young;Won, Moo-Ho;Cho, Sung-Woo
    • BMB Reports
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    • v.34 no.3
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    • pp.268-273
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    • 2001
  • In addition to the recognition site for glutamate, the N-methyl-D-aspartate (NMDA)-preferring glutamate receptor subtype shows a binding site for glycine. In this paper, we present the effects of 3-(4,6-dichloro-2-carboxymethylamino-5,7-dichloroquinoline-2-carboxylic acid (MDL 29951), a potent inhibitor of glycine binding to the NMDA receptor, on glutamate dehydrogenase (GDH) from bovine brains. The incubation of GDH isoproteins from bovine brains with MDL 29951 resulted in a dose-dependent loss of enzyme activity Separately or together, 2-oxoglutarate and NADH did not give an efficient protection against the inhibition, indicating that GDH isoproteins saturated with NADH or 2-oxoglutarate are still open to attack by MDL 29951. MDL 29951 was an uncompetitive inhibitor with respect to both 2-oxoglutarate and NADH for GDH isoproteins. These results suggest that the binding site of MDL 29951 is not directly located at the catalytic site, and the inhibition of GDH isoproteins by MDL 29951 is probably due to a steric hindrance, or a conformational change altered upon the interaction of the enzyme with its inhibitor. The inhibitory effects of MDL 29951 on GDH isoproteins were significantly diminished in the presence of ADP. GDH I reacted more sensitively with ADP than GDH II on the inhibition by MDL 29951. Our results suggest a possibility that the two types of GDHs are differently regulated by MDL 29951, depending on the physiological concentrations of ADP.

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Effects of Sperm Extracts on Sperm - Egg Binding in Mouse (생쥐의 정자 추출물이 정자-난자의 결합에 미치는 영향)

  • Kim, Moon-Kyoo;Gye, Myung-Chan;Choi, Kyoo-Wan;Yoon, Hyun-Soo;Kim, Jong-Heup
    • Clinical and Experimental Reproductive Medicine
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    • v.18 no.1
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    • pp.23-34
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    • 1991
  • In order to study the sperm-egg interaction during fertilization process in mouse, the effects of sperm concentration, the duration of capacitation and insemination, the stages of maturation and development of eggs, and sperm extracts and BSA on sperm binding to egg were examined. Sperm-egg binding was increased depending on sperm concentration within the range of $10^3-10^6$ sperm/ml. It showed the most numbers of sperm-egg binding at 60min from the beginning of preincubation(capacitation) and insemination, respectively. During sperm capacitation, sperm-egg binding inhibitor was released from sperm into the incubation medium. Sperm extracts containing trypsin-like enzyme which is secreted through the acrosome reaction increased the binding. BSA in the culture medium showed a positive effect on the binding. It is suggested that physicochemical alterations of zona pellucida in the process of maturation and fertilization of eggs leaded to inhibition of sperm-egg binding.

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Purification and Characterization of Trypsin Inhibitor from Alismatis Rhizoma and its Binding Protein, 10-Formyltetrahydrofolate Dehydrogenase (택사(Alismatis Rhizoma)로부터 트립신 저해제의 정제와 특성 규명 및 이와 결합하는 단백질, 10-Formyltetrahydrofolate Dehydrogenase에 관한 연구)

  • Kim, Ji-Man;Park, Jong-Ok;Shin, Young-Hee
    • YAKHAK HOEJI
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    • v.52 no.1
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    • pp.79-84
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    • 2008
  • Alismatis Rhizoma has been used as diuretics and antiphlogistics in the Chinese oriental medicine. A trypsin inhibitor was isolated from Alismatis Rhizoma using DEAE ion exchange column, trypsin affinity column, and FPLC chromatography, and its activity and characteristics were studied. The purifed Alismatis Rhizoma trypsin inhibitor (ARTI) was estimated to be about 22 kDa. The sequence determination on N-terminal amino acid residues and 84 amino acid residues has been completed, yet no homology has been found with trypsin inhibitors reported at NCBI. ARTI did not show inhibitory activities on chymotrypsin and elastase, however it exhibited a significant inhibitory activity on bovine trypsin, and formed a complex with rat liver 10-formyltetrahydrofolate dehydrogenase.

The MEK-1 Inhibitor, PD98059 reduces dioxin-induced CYP1A1 expression

  • Yim, Su-JIn;Suh, Jung-Ho;Park, Hyun-Sung
    • Proceedings of the Korean Society of Applied Pharmacology
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    • pp.238-238
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    • 2002
  • We studied whether kinase pathways are involved in TCDD-induced gene expression by treating specific kinase inhibitors ncluding MEK1 inhibitor PD98059, p38 inhibitor SB202190, PI-3 kinase inhibitor Wortmannin or LY294002 or protein tyrosine kinase inhibitor Genestein and then tested the effects of individual inhibitors on TCDD-induced gene expression of cytochromelAl gene (CYPlAl). Our results show that PD98059, MEK-1 inhibitor reduces dioxin-inducible transcription of CYPlAl. p44/p42MAPK, that is phosphorylated by Mek-1, are phosphorlylated by treatment of TCDD, peaking at lnM, 30min treatments. Overexpressions of p44/p42 MAPK dominant negative mutants suppress dioxin dependent transcription of DRE-driven reporter gene in a dose-dependent manner. Our results demonstrate that p44/p42 MAPK is essential for transcriptional activity of AHR/ARNT heterodimer. We found that PD98059 dose-dependently blocks TCDD-induced DRE binding of the AHR/ARNT heterodimer, thereby it reduces TCDD-induced gene expression. Therefore, our results indicate that Mek-1/p44/p42 MAPK pathway is involved in TCDD-induced gene expression, [This study was supported by a grant from Korean Research Foundation Grant (X01529)to H. Park]

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A Docking Study of Newly Found Natural Neuraminidase Inhibitor: Erystagallin A

  • Madhavan, Thirumurthy
    • Journal of the Chosun Natural Science
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    • v.4 no.4
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    • pp.273-277
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    • 2011
  • It's a threat for the public health that H1N1 (Influenza virus A) causes disease and transmits among humans. WHO (world health organization) declared that the infections caused by the new strain had reached pandemic proportions. The approved neuraminidase inhibitors (Zanamivir and Oseltamivir) and related investigative drug (BCX-1812) are potent, specific inhibitors of influenza A and B viruses. These drugs are highly effective to prevent influenza A and B infections. Early therapeutic use reduces illness duration and respiratory complications. Recently, we found one of the potent inhibitor of erystagallin A ($IC_{50}$ of 2.04 ${\mu}M$) for neuraminidase target, this inhibitor shows most similar structure to its natural substrate, sialic acid. Therefore, we chose 1l7f to get the receptor structure for docking study among many crystal structures. A docking study has been performed in Surflex-Dock module in SYBYL 8.1. In the present study, we attempt to compare the docking studies of pterocarpin and erystagallin A with neuraminidase receptor structure. In the previous report, the methoxy group of pterocarpin had H-bonding with Arg residues. The present docking results for erystagallin A showed the backbone of hydroxyl group shows significant H-bonding interactions with Arg152 and Arg292. The results showed that erystagallin A interacts more favorably with distinctive binding site rather than original active site. Therefore, we tried to reveal plausible binding mode and important amino acid for this inhibitor using docking and site id search calculations of Sybyl. The results obtained from this work may be utilized to design novel inhibitors for neuraminidase.

Discovery of Cyclin-dependent Kinase Inhibitor, CR229, Using Structure-based Drug Screening

  • Kim, Min-Kyoung;Min, Jae-Ki;Choi, Bu-Young;Lim, Hae-Young;Cho, Youl-Hee;Lee, Chul-Hoon
    • Journal of Microbiology and Biotechnology
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    • v.17 no.10
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    • pp.1712-1716
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    • 2007
  • To generate new scaffold candidates as highly selective and potent cyelin-dependent kinase (CDK) inhibitors, structure-based drug screening was performed utilizing 3D pharmacophore conformations of known potent inhibitors. As a result, CR229 (6-bromo-2,3,4,9-tetrahydro-carbolin-1-one) was generated as the hit-compound. A computational docking study using the X-ray crystallographic structure of CDK2 in complex with CR229 was evaluated. This predicted binding mode study of CR229 with CDK2 demonstrated that CR229 interacted effectively with the Leu83 and Glu81 residues in the ATP-binding pocket of CDK2 for the possible hydrogen bond formation. Furthermore, biochemical studies on inhibitory effects of CR229 on various kinases in the human cervical cancer HeLa cells demonstrated that CR229 was a potent inhibitor of CDK2 ($IC_{50}:\;3\;{\mu}M$), CDKI ($IC_{50}:\;4.9\;{\mu}M$), and CDK4 ($IC_{50}:\;3\;{\mu}M$), yet had much less inhibitory effect ($IC_{50}:>20\;{\mu}M$) on other kinases, such as casein kinase 2-${\alpha}1$ (CK2-${\alpha}1$), protein kinase A (PKA), and protein kinase C (PKC). Accordingly, these data demonstrate that CR229 is a potent CDK inhibitor with anticancer efficacy.

Hypocholesterolemic Soybean Peptide (IAVP) Inhibits HMG-CoA Reductase in a Competitive Manner

  • Pak, Valeriy V.;Koo, Min-Seon;Lee, Na-Ri;Oh, Su-Kyung;Kim, Myung-Sunny;Lee, Jong-Soo;Kwon, Dae-Young
    • Food Science and Biotechnology
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    • v.14 no.6
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    • pp.727-731
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    • 2005
  • Synthesized Ile-Ala-Val-Pro (IAVP) peptide, which has the highest hypocholesterolemic effect among a number of synthesized derivatives of Ile-Ala-Val-Pro-Gly-Glu-Val-Ala (IAVPGEVA) isolated from 11S globulin of soy protein by pepsin digestion, was selected for investigation in the present study. Using a recombinant Syrian hamster 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), we studied in detail the inhibition of this enzyme by IAVP and compared the action of this peptide to that of lovastatin, a known competitive inhibitor of this enzyme. The concentration of IAVP required for 50% inhibition ($IC_{50}$) of HMGR activity in given experimental conditions was $340\;{\mu}M$. Kinetic analysis revealed that the studied peptide is a competitive inhibitor of HMGR with respect to both 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) and nicotinamide adenine dinucleotide phosphate (NADPH), with an equilibrium constant of inhibitor binding ($K_i\;=\;[E][I]/[EI]$) of $61{\pm}1.2\;{\mu}M$ and $157{\pm}4.4\;{\mu}M$, respectively. At the same conditions, $K_i$ and $IC_{50}$ for lovastatin were $2.2{\pm}0.1\;nM$ and 12.5 nM, respectively. Thus, the given peptide interacts with HMGR as a bisubstrate, consequently blocking access of both substrates to the active sites. The achieved results suggest the design of new peptide sequences having a higher relative affinity to binding sites of this enzyme and an enhancement of their hypocholesterolemic properties.

Role of Shc and Phosphoinositide 3-Kinase in Heregulin-Induced Mitogenic Signaling via ErbB3

  • Kim, Myong-Soo;Koland, John G.
    • The Korean Journal of Physiology and Pharmacology
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    • v.4 no.6
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    • pp.507-513
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    • 2000
  • ErbB3/HER3 is a cell surface receptor which belongs to the ErbB/HER subfamily of receptor protein tyrosine kinases. When expressed in NIH/3T3 cells, ErbB3 can form heterodimeric coreceptor with endogenous ErbB2. Among known intracellular effectors of the ErbB2/ErbB3 are mitogen-activated protein kinase (MAPK) and phosphoinositide (PI) 3-kinase. In the present study, we studied relative contributions of above two distinct signaling pathways to the heregulin-induced mitogenic response via activated ErbB3. For this, clonal NIH-3T3 cell lines expressing wild-type ErbB3 and ErbB3 mutants were stimulated with $heregulin{\beta}_1$. While cyclin D1 level was markedly high and further increased by treatment of heregulin in cells expressing wild-type ErbB3, the elimination of either Shc binding or PI 3-kinase binding lowered both levels. This result was supported by the reduction of cyclin $D_1$ expression by preteatment with MAPK kinase inhibitor or PI 3-kinase inhibitor before stimulation with heregulin. In accordance with the cyclin $D_1$ expression, elimination of either Shc binding or PI 3-kinase binding reduced the heregulin-induced DNA synthesis and cell growth rate. Our results obtained by the comparison of wild-type and ErbB3 mutants indicate that the full induction of the cell cycle progression through $G_1/S$ phase by ErbB3 activation is dependent on both Shc/MAPK and PI 3-kinase signal transduction pathways.

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