• Food Engineering Progress
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• v.15 no.4
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• pp.289-296
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• 2011

Twenty four fractions by solvent extraction and/or acid precipitation from fruit body and culture broth of Inonotus obliquus were prepared, and their inhibitory effect against acetylcholinesterase (AChE) was investigated. Among these fractions, acid (1 M HCl) precipitates from cell-free culture broth and fruit body exhibited the highest inhibitory effect on AChE in vitro. Acid precipitates inhibited AChE activity in a concentration-dependant manner and $IC_{50}$ values of both acid precipitates were 0.53 mg/mL. The inhibition pattern was general non-competitive inhibition. The energetic parameters were also determined by dual substrate/temperature design. Both acid precipitates increased the values of Ea, ${\Delta}H,/;{\Delta}G$ and ${\Delta}H^{\ast}$ decreasing the value of ${\Delta}S$ for AChE. The results implied that the acid precipitates from I. obliquus increased the thermodynamic barrier, leading to the breakdown of ES complex and the formation of products as inhibitory mechanism.

• Food Engineering Progress
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• v.13 no.4
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• pp.251-261
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• 2009

In vitro physiological functions such as jack bean (Canavalia ensiformis) urease inhibitory activity and retarding effect of glucose/bile acid of Aloe vera gel concentrated by the optimized DIS (Dewatering Impregnation & Soaking) process conditions were examined. Urease inhibitory activity of DIS aloes ranged from 84.6 to 94.4%, which was similar to or higher than 86.3% of fresh aloe. Also, urease inhibitory activity of DIS aloes was maintained at initial levels after heat treatment (90$^{\circ}C$, 10 min.) and drying treatment (freeze or hot air drying). Urease inhibition pattern from Lineweaver-Burk plot indicated general non-competitive inhibition, and inhibition constants ($K_{IE}$ and $K_{IES}$) of DIS aloes were 41-149 and 87-163 $\mu$L/mL, respectively. DIS(glucose) and DIS(polyethylene glycol) exhibited the highest retarding effect of glucose and bile acid. Their retarding effects were about 1.6 and 1.8 folds higher than that of fresh aloe after 0.5 and 1 hr of the dialysis, respectively. Conclusively, the above in vitro physiological functions of Aloe vera gel concentrated by DIS process suggested that aloe products treated with DIS would have the potential benefits for protection against Helicobacter pylori and reduction of blood glucose and cholesterol levels.

• KSBB Journal
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• v.22 no.1
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• pp.30-36
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• 2007

The water-soluble or ethanol-soluble materials extracted from fruit bodies and cultured products (mycelium and broth) of H. erinaceum were prepared, and their inhibitory effect on acetylcholinesterase (AChE) activity from Electrophorous electricus was investigated. Inhibition of 75-85% for AChE activity at concentration of 10 mg/ml was obtained and the mechanism was due to general non-competitive inhibition. Especially, the supernatant of culture broth by ethanol treatment, exhibited a strong inhibition activity of 94% at 10 mg/ml. The samples from fruit body, mycelium and broth (supernatant and precipitate by ethanol treatment) which were extracted from H. erinaceum, were very effective to inhibit the initial stage oxidation of a linoleic acid at concentration of 0.1 mg/ml. The antioxidative activity of these samples were superior than rutin, vitamin C and tocopherol as antioxidative standards by FTC (ferric thiocyanate) method, and also showed the very strong antioxidative activity of 95% without significant difference of the samples by TBA-RS (thiobarbituric acid-reactive substance) method.

• Mycobiology
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• v.40 no.3
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• pp.173-180
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• 2012

A ${\beta}$-glucosidase from Penicillium italicum was purified with a specific activity of 61.8 U/mg, using a chromatography system. The native form of the enzyme was an 88.5-kDa tetramer with a molecular mass of 354 kDa. Optimum activity was observed at pH 4.5 and $60^{\circ}C$, and the half-lives were 1,737, 330, 34, and 1 hr at 50, 55, 60, and $65^{\circ}C$, respectively. Its activity was inhibited by 47% by 5 mM $Ni^{2+}$. The enzyme exhibited hydrolytic activity for p-nitrophenyl-${\beta}$-D-glucopyranoside (pNP-Glu), p-nitrophenyl-${\beta}$-D-cellobioside, p-nitrophenyl-${\beta}$-D-xyloside, and cellobiose, however, no activity was observed for p-nitrophenyl-${\beta}$-D-lactopyranoside, p-nitrophenyl-${\beta}$-D-galactopyranoside, carboxymetyl cellulose, xylan, and cellulose, indicating that the enzyme was a ${\beta}$-glucosidase. The $k_{cat}/K_m\;(s^{-1}mM^{-1})$ values for pNP-Glu and cellobiose were 15,770.4 mM and 6,361.4 mM, respectively. These values were the highest reported for ${\beta}$-glucosidases. Non-competitive inhibition of the enzyme by both glucose ($K_i=8.9mM$) and glucono-${\delta}$-lactone ($K_i=11.3mM$) was observed when pNP-Glu was used as the substrate. This is the first report of non-competitive inhibition of ${\beta}$-glucosidase by glucose and glucono-${\delta}$-lactone.

• Archives of Pharmacal Research
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• v.21 no.6
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• pp.782-784
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• 1998

Ginseng total saponin (GTS) can modulate dopaminergic activity at both presynaptic and postsynaptic dopamine receptors (Kim et al, 1998). The present study investigated t he effect of GTS on the bovine adrenal tyrosine hydroxylase (TH), which catalyze L/tyrosine to DOP. GTS inhibited the bovine adrenal TH by 42.4, 51.5 and 55.3% at concentrations of 40, 80 and 100${\mu}g$/ml, respectively. The IC50 value of GTS was 77.5${\mu}g$/ml. GTS exhibited noncompetitive inhibition with a substrate L-tyrosine. The Ki value was 155${\mu}g$/ml.

• 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.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 the Korean Chemical Society
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• v.24 no.4
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• pp.315-321
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• 1980

A steady-state kinetic study on a dye-coupled cytoplasmic polyol dehydrogenase from G. melanogenus was carried by the initial velocity measurements in the direction of the polyol oxidation and the product inhibition by D-fructose. For the initial rate experiments, D-mannitol and D-sorbitol were employed as the specific polyol substrates and 2,6-dichlorophenolin-dophenol (DPIP) as the specific cofactor substrate for the enzyme. When the polyol and DPIP were examined by varying one of substrates and by fixing the second, the corresponding reciprocal plots showed the typical parallel pattern. This suggests that the enzyme from G. melanogenus proceeds by a Ping Pong Bi-Bi mechanism in which the polyol may account as the first reactant-in, and the ketose formed as the first product-out, respectively. The product inhibition patterns obtained by D-fructose (one no-inhibition, one non-competitive, and two competitive) may also provide an additional conformatory evidence for the above mechanism. Based on the kinetic parameters obtained, it was also suggested that the rate-limiting step in the direction of polyol oxidation is associated with the release of the ketose from the Enzyme${\cdot}$Polyol complex.

• BMB Reports
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• v.42 no.3
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• pp.142-147
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• 2009

Small-molecule inhibitors of protein kinases have contributed immensely to our understanding of biological signaling path-ways and have been exploited therapeutically for the treatment of cancers and other disease states. The pyridinyl imidazole compounds SB 203580 and SB 202190 were identified as ATP competitive antagonists of the p38 stress-activated protein kinases and have been widely used to elucidate p38-dependent cellular processes. Here, we identify SB 203580 and SB 202190 as potent inhibitors of stress-induced CREB phosphorylation on Serine 111 (Ser-111) in intact cells. Unexpectedly, we found that the inhibitory activity of SB 203580 and SB 202190 on CREB phosphorylation was independent of p38, but instead correlated with inhibition of casein kinase 1 (CK1) in vitro. The inhibition of CK1-mediated CREB phosphorylation by concentrations of pyridinyl imidazoles commonly employed to suppress p38, suggests that in some cases conclusions of p38-dependence derived solely from the use of these inhibitors may be invalid.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.121-128
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• 2006

The purified xylanase from Bacillus alcalophilus AX2000 was modified with various chemical modifiers to determine amino acid residues in the active site of the enzyme. Treatment of the enzyme with group-specific reagents such as carbodiimide or N-bromosuccinimide resulted in complete loss of enzyme activity. These results suggested that these reagents reacted with glutamic acid or aspartic acid and tryptophan residues located at or near the active site. In each case, inactivation was performed by pseudo first-order kinetics. Inhibition of enzyme activity by carbodiimide and N-bromosuccinimide showed non-competitive and competitive inhibition type, respectively. Addition of xylan to the enzyme solution containing N-bromosuccinimide prevented the inactivation, indicating the presence of tryptophan at the substrate binding site. Analysis of kinetics for inactivation showed that the loss of enzyme activity was due to modification of two glutamic acid or aspartic acid residues and single tryptophan residue.