• BMB Reports
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• v.35 no.5
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• pp.443-451
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• 2002

Malonate is a three-carbon dicarboxylic acid. It is well known as a competitive inhibitor of succinate dehydrogenase. It occurs naturally in biological systems, such as legumes and developing rat brains, which indicates that it may play an important role in symbiotic nitrogen metabolism and brain development. Recently, enzymes that are related to malonate metabolism were discovered and characterized. The genes that encode the enzymes were isolated, and the regulation of their expression was also studied. The mutant bacteria, in which the malonate-metabolizing gene was deleted, lost its primary function, symbiosis, between Rhizobium leguminosarium bv trifolii and clover. This suggests that malonate metabolism is essential in symbiotic nitrogen metabolism, at least in clover nodules. In addition to these, the genes matB and matC have been successfully used for generation of the industrial strain of Streptomyces for the production of antibiotics.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3229-3232
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• 2011

A FRET-based high-throughput screening system was developed for the discovery of competitive smallmolecule Hsp90 inhibitors. The biarsenical fluorescein derivative FlAsH and dabcyl-conjugated Hsp90 inhibitor GM were employed as the FRET donor and quencher, respectively. The spatial proximity perturbation between FlAsH-labeled Hsp90N and GM-dabcyl upon treatment of a small molecule led to changes in the FRET-induced fluorescence, monitored in a high-throughput fashion.

• Archives of Pharmacal Research
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• v.21 no.2
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• pp.207-211
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• 1998

Three prolyl endopeptidase inhibitors were isolated and identified as luteolin, quercetin and ${\beta}$-sitosterol-3-O-${\beta}$-D-glucopyranoside with $IC_{50}$ of 0.17, 0.19 and 27.5 ppm, respectively. The inhibition of two flavonoids were non-competitive with substrate. Twenty authentic flavonoids were tested in order to investigate structure-activity relationship. No significant relationship was found in them, however, catechol moiety of B-ring and 7-OH group in flavonoid skeleton were seemed to be responsible for the stronger activity.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05a
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• pp.92-92
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• 2002

Recently we have reported that various hydroxystilbenes show strong inhibition of human P450 1 activity. A series of synthetic trans-stilbene derivatives were prepared and their inhibitory potentials were evaluated with the bacterial membrane of recombinant human P450 1A1, 1A2 or 1B1 coexpressed with human P450/NADPH-450 reductase to find new candidates for cancer chemoprevention.(omitted)

• BMB Reports
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• v.35 no.3
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• pp.302-305
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• 2002

Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at $27^{\circ}C$ using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to $140\;{\mu}M$ by the microcalorimetry method, which agrees well with the value of $143\;{\mu}M$ for the inhibition constant that was obtained from the spectroscopy method.

• BMB Reports
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• v.36 no.4
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• pp.421-425
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• 2003

The serine/threonine protein kinase family is a large and diverse group of enzymes that are involved in the regulation of multiple cellular pathways. Elevated kinase activity has been implicated in many diseases and frequently targeted for the development of pharmacological inhibitors. Therefore, non-radioactive antibody-based kinase assays that allow high throughput screening of compound libraries have been developed. However, they require a generation of antibodies against the phosphorylated form of a specific substrate. We report here a time-resolved fluorescence assay platform that utilizes a commercially-available generic anti-phosphothreonine antibody and permits assaying kinases that are able to phosporylate threonin residues on protein substrates. Using this approach, we developed an assay for Cdc7/Dbf4 kinase activity, determined the $K_m$ for ATP, and identified rottlerin as a non-ATP competitive inhibitor of this enzyme.

• Microbiology and Biotechnology Letters
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• v.21 no.2
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• pp.139-143
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• 1993

Three isoflavonoids having tyrosinase-inhibiting activity were isolated from the culture filtrate of Streptomyces sp. 20747. Their structures were determined by UV, EI-MS, 1H-NMR, 13C-NMR to be daidzein, daidzein 7-rhamnoside, and genistein 7-rhamnoside, which were competitive with substrate and had IC50 value of 14, 19, and 16 ng/ml, respectively to mushroom tyrosinase and did not inhibit melanin production of Streptomyces bikiniensis. Soybean meal as well as peptone were found to be a good nitrogen source for tyrosinase-inhibiting isoflavonoids production, susgesting that soybean meal is not the origin of tyrosinase inhibiting isoflavonoids formation in Streptomyces sp. 20747 strain.

• Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.183-190
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• 2012

The purpose of this study was the purification and characterization of an angiotensin I converting enzyme (ACE) inhibitory peptide purified from enzymatic hydrolysates of rainbow trout Oncorhynchus mykiss muscle. After removal of lipid, the approximate composition analysis of the rainbow trout revealed 24.4%, 1.7%, and 68.3% for protein, lipid, and moisture, respectively. Among six hydrolysates, the peptic hydrolysate exhibited the highest ACE inhibitory activity. We attempted to purify ACE inhibitory peptides from peptic hydrolysate using high performance liquid chromatography on an ODS column. The $IC_{50}$ value of purified ACE inhibitory peptide was $63.9{\mu}M$. The amino acid sequence of the peptide was identified as Lys-Val-Asn-Gly-Pro-Ala-Met-Ser-Pro-Asn-Ala-Asn, with a molecular weight of 1,220 Da, and the Lineweaver-Burk plots suggested that they act as a competitive inhibitor against ACE. Our study suggested that novel ACE inhibitory peptides purified from rainbow trout muscle protein may be beneficial as anti-hypertension compounds in functional foods.

• Animal cells and systems
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• v.2 no.2
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• pp.233-238
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• 1998

Certain basic characteristics of choline uptake in nerve terminals were studied with synaptosomes from rat hippocampus. Synaptosomal $[^3H]$-choline uptake was clarified as specific and high affinity by low Km value(2.2 uM), Na+-dependency and high sensitivity to hemicholinium-3, a competitive inhibitor of choline uptake. Choline uptake into synaptosomes was linearlys related to Na+ concentration and membrane potential. Extracellular Ca2+ modulated the choline uptake, but probably not through increase of intracellular $Ca^{2+}$, because this modulation was not affected the by high $K^+$-depolarization. EGTA (2mM) added for $Ca^{2+}$-free condition had a peculiar effect of decreasing choline uptake. These results suggest that Ca2+ may play an important role in regulating the metabolism of acetylcholine in the nerve terminals directly through the increase of acetylcholine release.

• Archives of Pharmacal Research
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• v.28 no.4
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• pp.400-404
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• 2005

Activity-guided fractionation of a hexane-soluble extract of the roots of Lithospermum erythrorhizon, using a mouse brain monoamine oxidase (MAO) inhibition assay, led to the isolation of two known naphthoquinones, acetylshikonin and shikonin, and a furylhydroquinone, shikonofuran E. These compounds were shown to inhibit MAO with $IC_{50}$ values of 10.0, 13.3, and $59.1 {\mu}M$, respectively. Although no specificity for MAO-A and MAO-B was shown by acetylshikonin and shikonin, a Lineweaver-Burk plot analysis indicated that the inhibition was competitive for both MAO-A and MAO-B activity.