• 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.

• Korean Journal of Medicinal Crop Science
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• v.11 no.4
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• pp.264-267
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• 2003

Korean medicinal plants were screened for their inhibitory activity against HIV-1 protease. The inhibitory activity of protease was determined by incubating the extracts in reaction mixtures containing protease and substrate $His-Lys-Ala-Arg-Val-Leu-(p-NO_{2}-Phe)-Glu-Ala-Nle-Ser-NH_{2}$ to perform proteolytic cleavage reactions. In this study the twenty six extracts from medicinal plants were investigated. Of the extracts tested, the extracts from the stem of Morus alba. exhibited the strongest activity with inhibition of 81% at a concentration of $100{\mu}g/ml$. The extracts of the flower of Saxjfraga stolonifera, and stems of Euonymus japonica and Castanea crenata showed appreciable inhibitory activity (>50%) against HIV-1 protease at same concentration.

• 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.

• The Journal of Korean Physical Therapy
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• v.11 no.3
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• pp.133-140
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• 1999

Why does the CNS not regenerate after injury? The failure of axonal regeneration in the CNS after injury is not due to an inherent inability of these neurons to regrowth axon. Recently, an inhibitory substrate effect of CNS has been discovered which could be directly invoked in the lack of regeneration. The failure of axon regrowth in the CNS is crucially influenced by the presence of neurtie growth inhibitor NI35/250 and possibly also by molecules such as myelin associated glycoprotein(MAG) and chondroitin sulphate proteoglycans(CSPGs). The application of the monoclonal antibody IN-1, which efficinetly neutralizes the N135/250 inhibitory molecules. This new finding has a strong impact on the development of, a new neuroscienctific research directed to stimulate axonal regeneration. In this review summarize the current knowledge on the factors and molecules involved in the regeneration failure.

• YAKHAK HOEJI
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• v.40 no.1
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• pp.65-71
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• 1996

Characterization of Polyphenol oxidase (PPO) in Perillae Folium, particullarly inhibitor studies were investigated. This enzyme was stable at pH 5.0 and the residual activity of PPO at ${\geq}$ ph 5.5 was estimated to be very low. PPO activity was decreased slightly by adding amino acid with catechol as a substrate, particullary PPO activity was inhibited markedly by cystein, histidine, lysine and arginine. In the absorption spectra of the product formed when catechol was oxidized by PPO, with a ${\lambda}_{max}$ at 410nm, the peak shifted toward ${\lambda}_{max}$ 520nm by addition of L-proline. At relatively low concentrations($10^{-3}M$), sulfite and dithiothreithol completely inhibited PPO activity. Inhibition of PPO activity by amino acids and inhibitors increased or decreased depending on the pH used to measure it.

• Bulletin of the Korean Chemical Society
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• v.23 no.7
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• pp.1003-1010
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• 2002

Caspase 3, a member of cysteine protease family, is well known as a major apoptosis effector and is involved in cell death as a result of ischemic diseases such as stroke and myocardial infarction, therefore the inhibition of caspase 3 may protect those apoptotic cell damages. During the high-throughput screening of the compounds from the Korea Chemical Bank, berberine derivatives (A and B), an isoquinoline alkaloid, have been identified as potential inhibitors for caspase 3. Based on this finding we carried out molecular modeling study to identify the pharmacophoric elements of berberine structure which interact with a substrate-recognition binding site of caspase 3 and came up with several novel scaffolds. In this report, we will discuss the molecular modeling, syntheses and the enzyme inhibitory activities of these novel compounds.

• The Korean Journal of Food And Nutrition
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• v.9 no.2
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• pp.167-175
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• 1996

This studies were conducted to select optimal enzyme that produced hydrolysate from soybean, and to evaluated functionality of hydrolysate. Soybean powder was suspended with water and hydrolyzed by seven commercial proteases. Hydrolysate produced with protease from Bacillus subtilis showed the highest inhibition effect on the activity of angiotension converting enzyme(ACE), and the condition of enzymatic hydrolysis was 5cA substrate concentration, 0. l% enzyme concentration, 4 hour hydrolysis time. Under above optimum condition, soybean was hydrolyzed with protease from Bacillus subtilis yielding a DH (degree of hydrolysis) of about 49%. Hyrophobicity of hydrolysate was not correlated with the inhibition effect on ACE activity. The functionality of hydrolysate was significantly influenced by pH. Solubility of hydrolysate at alkali solution was greater than that at acidic solution.

• Archives of Pharmacal Research
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• v.28 no.2
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• pp.159-163
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• 2005

The effects of sedative peptide alkaloids from Zizyphus species on calmodulin- dependent protein kinase II were investigated. Protein kinase II activity was assayed on the basis of its ability to activate tryptophan 5-monooxygenase as its substrate in the presence of calmodulin. All thirteen alkaloids tested were stronger inhibitors than chlorpromazine ($IC_50,\;98{\mu}M$) on calmodulin-dependent protein kinase II. Among them, the most potent inhibitor was daechuine S27 ($IC_{50},\;2.95{\mu}M$), which was stronger than pimozide ($IC_{50},\;15.0{\mu}M$).

• Archives of Pharmacal Research
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• v.16 no.4
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• pp.295-299
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• 1993

Human renal dipeptidase (RDPase) was purified from surgically removed kdneys of renal stone aptients by affinity chromatography using its specific inhibitor, cilastain, as the ligand. The partial purified RDPase of 6 mg exhivited specific activity of 99.4 unit/mg with 2, 029 fold purification. it was composed of a slow moving major band (96%) and a fast moving minor band (4%). The minor band was not a contaminant as it showed a dipeptidase-specific activity. The kinetic parameters determined with glycyldehydrophenylalanine (Gdp) as synthetic substrate were Vmax, $322.6\;\mu{mol/min/mg}$ and km, 0.120 mM. This experiment provided biochemical evidences that sugically removed, nonfunctional kidneys in respect of glomerular filtration still retained high activity of renal dipeptidase.

• Archives of Pharmacal Research
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• v.24 no.4
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• pp.292-296
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• 2001

Three prolyl endopeptidase (PEP) inhibitors were isolated from the methanolic extract of green tea leaves. They were identified as (-)-epigallocatechin gallate, (-)-epicatechin gallate, and (+)-gallucatechin gallate with the $IC_{50}$ values of 1.42${\times}$$10^{-4}$mM, $1.02{\times}10^{-2}$mM, and $1.09{\times}10^{-4}$mM, respectively. They were non-competitive with a substrate in Dixon plots and did not show any significant effects against other serine proteases such as elastase, trypsin, and chymotrypsin, suggesting that they were relatively specific inhibitors against PER The isolated compounds are expected to be useful for preventing and curing of Alzheimer's disease.