• Journal of Life Science
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• v.26 no.7
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• pp.826-834
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• 2016

The present investigation was undertaken to examine the effectiveness of the combination treatment of an Hsp90 inhibitor and a SIRT1 inhibitor on suppressing the growth of chemo-resistant human cancer cells. We showed that inhibition of SIRT1 effectively potentiated the cytotoxicity of 17-allylamino-17-demethoxygeldanamycin (17-AAG) and reversed Hsp90 inhibitor resistance in multidrug-resistant (MDR) human ovarian HeyA8-MDR cells. Amurensin G, a potent natural SIRT1 inhibitor, enhanced Hsp90 inhibitor-mediated abrogation of the Hsp90 chaperone function and accelerated degradation of mutated p53 (mut p53), an Hsp90 client protein, by up-regulation of ubiquitin ligase CHIP. Knock-down of CHIP significantly attenuated amurensin G-induced mut p53 degradation. Down-regulation of mut p53 reduced the expression of heat shock factor1 (HSF1)/heat shock proteins (Hsps), a major cause of Hsp90 inhibitor resistance, which led to sensitization of the MDR cells to the Hsp90 inhibitor by the SIRT1 inhibitor. Amurensin G potentiated cytotoxicity of the Hsp90 inhibitor in HeyA8-MDR cells through suppression of 17-AAG-induced Hsp70 and Hsp27 induction via down-regulation of mut p53/HSF1, and it caused activation of PARP and inhibition of Bcl-2. Our data suggests that SIRT1 inhibitors could be used to sensitize MDR cells to Hsp90 inhibitors, possibly through suppression of the mut p53/HSF1-dependent pathway, and a novel mut p53-directed action of SIRT1 inhibition could effectively prevent mut p53 accumulation in MDR cells.

• KSBB Journal
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• v.8 no.4
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• pp.375-381
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• 1993

The microorganisms producing a lipoxygenase inhibitor were screened from a wide variety of sources. The isolated strain was assigned to genus Penicillium by its cultural and morphological characteristics. The proper medium for the production of lipoxygenase inhibitor was composed of glucose 3.0%, ammonium sulfate 0.4%, and potassium phosphate (dibasic) 0.1%. The cultivation for lipoxygenase inhibitor production was carried out in 500m1 Erlenmyer flasks containing 100m1 of the medium at $30^{\circ}C$ by cultivating reciprocally. The highest lipoxygenase inhibitor production was observed after 8 days of cultivation. The inhibitor was the low molecular weight substance and inhibited specifically soybean origin lipoxygenase.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.895-900
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• 2002

A soil microorganism producing ${\alpha}$- and ${\beta}$-glucosidase inhibitors was identified as Bacillus lentimorbus, based on the fatty acid and morphological analyses, along with biochemical and physiological tests. The ${\alpha}$-glucosidase inhibitor was highly produced by this strain in a culture medium containing $0.25\%$ of sodium glutamate and $0.5\%$ of glucose, pH 8.0 at $30^{\circ}C$ for 2 days. The ${\alpha}$-glucosidase inhibitor from culture filtrate of his strain was identified as water soluble, organic solvent nonextractable, and heat stable. In addition to ${\alpha}$-glucosidase inhibitor, this strain also produced ${\beta}$-glucosidase inhibitor in he same culture medium and this inhibitor showed an antifugal activity against Botrytis cinerea. While the production of ${\alpha}$- glucosidase inhibitor was decreased by a glucose concentration higher than $1\%$, the production of ${\beta}$-glucosidase inhibitor was lot Influenced by a glucose concentration higher than $20\%$. The ${\alpha}$-glucosidase inhibitor from culture filtrate of this strain was separated from the ${\beta}$-glucosidase inhibitor through Sephadex G-100 column chromatography.

• Microbiology and Biotechnology Letters
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• v.27 no.3
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• pp.215-222
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• 1999

Methylotrophic actinomycetes No. 155 produced an aminoglycoside antibiotics(AG)-resistant inhibitor. We have previously reported that the inhibitor shows strong inhibition to sisomicin-resistant strain. In order to understand the functions of inhibitor and sisomicin-resistance, characterizations and purification of inhibitor were investigated. Strain No. 155 was tentatively identified as Nocardiopsis sp. based on morphological and some physiological characteristics. In the antimicrobial activity test, the addition of inhibitor to sisomicin showed a reduction effect of MIC on the test strains such as Gram(+), Gram(-) bacteria and yeasts. The combination of the inhibitor and various antibiotics revealed synergistic against E. coli K-12 and B. subtilis PCI 219. The induced intracellular proteins from sisomicin-resistant strain exhibited the sisomicin inactivation by invitro test. And the induced intracellular proteins were inactivated by addition of the inhibitor. The inhibitor compound was purified by anion exchange chromatography(Dowex-1) and HPLC using Asahipak ES-502C column. The purified inhibitor compound was detected in a single peak(above 98.5% purity) through the HPLC analysis.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.28-32
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• 2006

Protease inhibitor of 72.6 kDa was successively purified from chum salmon (Oncorhynchus keta) eggs by ion exchange, gel permeation, and affinity chromatographies. Protease inhibitor was purified with yield and purification fold of 1.50% and 58.11, respectively. SDS-PAGE results showed purified protease inhibitor consisted of two protein subunits of 54.0 and 18.6 kDa. Chum salmon inhibitor exhibited stability between 20 and $40^{\circ}C$ in weak acid environment (PH 6), and inhibited papain and cathepsin, members of cysteine protease, but not chymotrypsin. The protein inhibited cathepsin more effectively than did egg white protease inhibitor, whereas the reverse was true for papain. These results indicate chum salmon egg inhibitor is heterodimer, thus the inhibitor was classified as cysteine protease inhibitor.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.97-106
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• 2012

To investigate the application of corrosion inhibitor on water supply pipes, turbidity, magnitude of corrosion, composition of scale and concentration of metals from an old steel pipe were analysed under inhibitor addition. The concentration of turbidity, iron and copper from the pipes under inhibitor application was 12 ~ 14% of the case which no inhibitor was applied, which suggests the application of inhibitor was very effective for internal corrosion control. In addition, SEM, EDX, XRD and XRF test results showed that application of inhibitor was effective for the decrease of iron concentration and increase of oxygen, phosphorus and calcium concentration, which suggested the existence of protective layer. Therefore, the occurrence of red water will be significantly decreased when inhibitor was applied to the old steel pipes.

• BMB Reports
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• v.50 no.6
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• pp.329-334
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• 2017

Protein tyrosine phosphatases (PTPs) play crucial roles in signal transduction and their functional alteration has been detected in many diseases. PTP inhibitors have been developed as therapeutic drugs for diseases that are related to the activity of PTPs. In this study, PTP inhibitor XIX, an inhibitor of CD45 and PTEN, was investigated whether it inhibits other PTPs. Protein tyrosine phosphatase non-receptor type 2 (PTPN2) was selectively inhibited by the inhibitor in a competitive manner. Drug affinity responsive target stability (DARTS) analysis showed that the inhibitor induces conformational changes in PTPN2. Phosphorylation levels of signal transducer and activator of transcription 3 (STAT3) at Tyr-705, a crucial site for STAT3 activation and target site of PTPN2, decreased upon exposure to the inhibitor. Our results suggest that PTP inhibitor XIX might be considered as an effective regulator of PTPN2 for treating diseases related to PTPN2.

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.100-105
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• 2005

The lactate dehydrogenase (EC 1.1.1.27, LDH) inhibitors were isolated from the LDH-free crude mitochondrial fraction of skeletal muscle in Syrian hamster (Mesocricetus auratus) and Korean native cattle (Bos taurus coreanae). The LDH inhibitor in skeletal muscle of M. auratus was successfully isolated by the treatment with 175 mM NaCl and ultrasonic. The LDH inhibitor in skeletal muscle of B. taurus coreanae was highly stable to heat and LDH fu isozyme was largely inhibited by the LDH inhibitor. The molecular weight of inhibitor was 22 kDa. Inhibitor played an important role in the binding of LDH with the mitochondria in tissues of skeletal muscle, kidney and liver except heart.

• Applied Biological Chemistry
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• v.33 no.4
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• pp.287-292
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• 1990

Eight(I through VII) of Bowman-Birk proteinase inhibitor have been isolated from soybean with DEAE-Sephadex A-50. Inhibitor VII was a typical BBTI, showing high cysteine content(17%/mole) ud low trypsin to chymotrypsin inhibiting activity(TIA/CIA= 1.0) with the independent reactive site to each enzyme. Dissociation constant of trypsin-BBTI and chymotrypsin-BBTl complexes were $9.17{\times}10^{-9}M$ and $5.14{\times}10^{-8}M$, respectively. Inhibitor Vll was extremely heat stable. Six hours heat treatment at $100^{\circ}C$ caused only 50% decrease in it's original inhibiting activity. Except inhibitor III,6 other isoinhibitors differed from a typical BBTI in TIA/CIA, values, ranging from 3 to 29.

• Environmental Engineering Research
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• v.17 no.1
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• pp.17-25
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• 2012

Concern about green water problem has surfaced as a serious issue in Korea. In order to solve this problem, it is necessary to research inhibition of green water and corrosion control of copper pipe in water service. This paper discovered that moderate corrosion inhibitors can solve the green water problem and copper corrosion in water service by adding the optimal concentration of corrosion inhibitors based on regulation. Firstly, in the case of phosphate based corrosion inhibitors, as dosage of the corrosion inhibitor increases from 1 mg/L to 5 mg/L, the relative effect of corrosion inhibitor declines rapidly. Secondly, except for 1 mg/L dosage of silicate based inhibitor, relative effects of the inhibitor displays a positive number depending on inhibitor concentration. The most significant result is that the amount of copper release shows a downward trend, whereas the phosphate based inhibitor accelerates copper ion release as the inhibitor dosage increases. Thirdly, as the dosage of mixed inhibitors increases to 10 mg/L, the copper release change shows a similar trend of phosphate based inhibitor. Lastly, according to the Langelier saturation index (LI), silicate based inhibitors have the most non corrosive value. Larson ratio (LR) indicates that phosphate based inhibitors are the least corrosive. Korea water index (KWI) represents that silicate based inhibitors are most effective in controlling copper pipe corrosion.