• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.31-35
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• 1998

1. INTRODUCTION : Recognition and binding of organic substrates by biological molecules are of vital importance in biophysics and biophysical chemistry. Most studies of the application focused on the development of biosensors, which detected reaction products generated by the binding between enzymes and substrates. Other types of biosensors in which membrane proteins (e.g., nicotinic acetylcholine receptor, auxin receptor ATPase, maltose bining protein, and glutmate receptor) were utilized as a receptor function were also developed. In the previous study[1], the shifts in membrane potential, caused by the injection of substrates into a permeation cell, were measured using immobilized glucose oxidase membranes. It was suggested that the reaction product was not the origin of the potential shifts, but the changes in the charge density in the membrane due to the binding between the enzyme and the substrates generated the potential shifts. In this study, $\gamma$-globulin was immobilized (entrapped) in a poly($\gamma$-amino acid) network, and the shifts in the membrane potential caused by the injection of some amino acids were investigated.

• YAKHAK HOEJI
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• v.45 no.1
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• pp.46-54
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• 2001

Protein carboxyl Ο-methylation is a kind of enzymatic reaction producing carboxyl methylester catalyzed by protein carboxyl Ο-methyltransferases at the carboxyl group of amino acid residues in polypeptide. Since the finding of carboxyl methylesterl many studies have been focused on the under-standing of biological functions in eukaryotes but still not clear except for roles in Ras attachment to membrane and protein repair. In this study, we investigated the protein carboxyl methylation in porcine liver and testis in respect of identification and characterization of carboxyl methylesters and natural proteinous substrates using pH stability of the esters and electrophoresis under acidic and basic conditions. We detected several kinds of methyl esters, 3 kinds each in cytosolic fractions from liver and testis. Under the treatment of strong acid and base, the ratio between base-stable substrates and unstable ones in liver (4 : 6) was different from the ratio obtained in testis (6 : 4). The methyl accepting capacities were affected by enzymatic proteolysis between the range of 55 to 65% in liver and of 35 to 45% in testis. Separation of the methylated proteins by acidic electrophoresis in the presence of urea and SDS revealed distinctively natural substrates of 26, 33 and 80 kD in the cytosol from liver and of 14, 25, 32 and 86 kD from testis. Most of the labelling, however were lost following electrophoresis under moderate alkaline condition, except for molecules of newly detected 7 and 17 kD in livers and 15, 29, 40 and 80 kD in testis. From these results, it was proposed that protein carboxyl Ο-methylation in each organs may be catalyzed by different classes of protein carboxyl Ο-methyltransferases. In addition, it is suggested that the protein carboxyl methylation in liver and testis may have different patterns in respect of natural substrates.

• The Korean Journal of Mycology
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• v.17 no.2
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• pp.57-65
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• 1989

The effect of various cellulosic and hemicellulosic substrates on the induction of cellulase and xylanase complexes in Aapergillus nidulans was investigated. The most efficient substrates for the induction of cellulase and xylanase complexes were carboxymethylcellulose for endoglucanase, cellobiose for ${\beta}-glucosidase$, and xylan for endoxylanase and ${\beta}-xylosidase$, respectively. However, the mixtures of these substrates, especially CMC-xylan and CMC-xylan-laminarin mixture, were much more effective not only for the enhancement of the biosynthesis of all the cellulase and xylanase complexes but also for the balanced production of these enzyme components than individual substrate. The polyacrylamide gel electrophoresis followed by activity staining showed the variation in the patterns and relative intensity of ${\beta}-glucosidase$, endoglucanase and endoxylanase components in individual enzyme preparations from A. nidulans cultures grown on different substrates. These results suggest that the biosynthesis is of cellulase and xylanase systems in A. nidulans is regulated in coordination at the level of induction.

• Korean Journal of Environmental Agriculture
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• v.36 no.3
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• pp.217-221
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• 2017

BACKGROUND: For the food safety of cultivated mushroom, information on the safety of agricultural by-products imported as medium substrates for mushroom cultivation is urgently needed. Therefore, this study was performed to detect the presence of heavy metals, residual pesticides, and nutrient component in the imported medium substrates. METHODS AND RESULTS: Six kinds of medium substrates imported from nine countries from 2015 to 2017 were investigated. A mercury analyzer MA-2000 and an inductively coupled plasma spectrometer OPTIMA 7000DV were used to analyze mercury, lead, arsenic, copper, nickel and cadmium. All of these heavy metals were detected at lower level than heavy metal tolerance standard level of by-product fertilizer in Korea. When 246 kinds of residual pesticides were examined by GC and HPLC, imidacloprid, thiamethoxam and carbendazim were detected from Egyptian beet pulp, Indian cottonseed meal and cottonseed hull, respectively. The content of nutrient components (water, crude ash, crude fat, crude protein and crude fiber) varied among imported countries and the medium substrates. CONCLUSION:The presence of heavy metals and residual pesticides in imported medium substrates for mushroom cultivation was confirmed. For the safe production of mushroom, this study shows that imported medium materials for mushroom cultivation need to be managed through continuous monitoring.

• Korean Journal of Environmental Biology
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• v.33 no.3
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• pp.352-359
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• 2015

In order to investigate the occurrence of Pectinatella magnifica in Nakdong River, extensive series of sampling was conducted through July to November of 2014. Results revealed that these species show preference to attach themselves on natural substrates over artificial substrates. P. magnifica does not show preference for specified substrates, but itappearthat availability of substrates determines their specific distribution. Considering that most commonly found substrates in Nakdong River were natural substrates such as dead twig, woody plants or aquatic plants, it is possible that high availability of substrates is one of the principal factors which increase the rates of growth and distribution of P. magnifica.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.164-168
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• 2000

The obhective of this minireview is to examine how cometabolic biodegradation of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) might be af fected by plant terpenes and lignins as natural substral substrates abundant in mature. The topics covered, hence are environmental sinficance of PCBs and PAHs, nature and disribution of plant terpences and lignin, structural and metabolic similarities of the natural compounds to PCBs and PAHs, and possible roles of the natural substrates in inducing the biodegradative patathways of PCBs and PAHs

• Journal of Microbiology and Biotechnology
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• v.6 no.3
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• pp.179-183
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• 1996

Synergism among endo-xylanase, $\beta$-xylosidase, and $\alpha$-L-arabinofuranosidase from Bacillus stearothermophilus upon xylan hydrolysis was investigated by using birchwood, oat spelt, and arabinoxylan as substrates. Endo-xylanase and $\beta$-xylosidase showed the cooperative action on all three substrates tested, revealing the fact that $\beta$-xylosidase assists endo-xylanase action in xylan hydrolysis by relieving the endproduct inhibition upon endo-xylanase conferred by xylooligomers. $\alpha$-L-Arabinofuranosidase also exhibited synergic effects with endo-xylanase and $\beta$-xylosidase on oat spelt and arabinoxylan, which contained significant amounts of arabinose side chains, whereas no synergism was detected on birchwood xylan which had only trace amounts of the side chain. Thus, the hydrolysis of xylan containing arabinose side chains required $\alpha$-L-arabinofuranosidase as well as endo-xylanase and $\beta$-xylosidase for the better hydrolysis of the substrates, and these enzymes work cooperatively in order to maximize the extent and rate of xylan hydrolysis.

• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.368-379
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• 2018

Objective of this work is to study the effects of a saline solution used to pretreat lignocellulosic material derived from champak timber. The native lignocellulosic solids, in powder form, were mixed with saline water solutions of three different concentrations and maintained for 2 weeks without stirring. The treated solids were washed, recovered, and then dried under sunlight. The substrates were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The crystallinity (CrI), lateral order index (LOI), total crystallinity index (TCI), and surface morphologies of all the samples were determined. The treated biomass structures were compared with controls. The data show that the structures of all the treated substrates changed, as indicated by CrI. CrI of the treated substrates decreased significantly compared with that of the original wood, as did LOI and TCI quantities, whereas the HBI parameter increased. The results indicate that the saline water pretreatment modified the wood samples.

• Natural Product Sciences
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• v.20 no.1
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• pp.1-6
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• 2014

P-glycoprotein (P-gp) is a permeability glycoprotein also known as multidrug resistance protein 1 (MDR1). P-gp is an ATP-binding cassette (ABC) transporter that pumps various types of drugs out of cells. These transporters reduce the intracellular concentrations of drugs and disturb drug absorption. The Caco-2 cell permeability assay system is an effective in vitro system that predicts the intestinal absorption of drugs and the functions of enzymes and transporters. Rhodamine-123 (R-123) and digoxin are well-known P-gp substrates that have been used to determine the function of P-gp. Efflux of P-gp substrates by P-gp has been routinely evaluated. To date, a number of herbal medicines have been tested with Caco-2 cell permeability assay system to assess bioavailability. There are growing efforts to find phytochemicals that potentially regulate P-gp function. The Caco-2 cell permeability assay system is a primary strategy to search for candidates of P-gp inhibitors. In this mini review, we have summarized the P-gp modulation by herbal extracts, decoctions or single components from natural products using Caco-2 cell permeability assays. Many natural products are known to regulate P-gp and herbal medicines could be used in combination with conventional drugs to enhance bioavailability.

• Journal of Microbiology
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• v.42 no.3
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• pp.205-210
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• 2004

The sequence coding for carboxymethylcellulase (CMCase, CelC) was isolated from the DNA of Salmonella typhimurium URl. Comparison between the deduced amino acid sequence of CelC (368 amino acid residues, Molecular mass 41 kDa) and that of the previously published CMCase revealed that this enzyme belongs to the cellulase family 8 and D. The protein was overproduced in Escherichia coli using T7 expression system, and its activity was confirmed by CMC-SDS-PAGE. When the overexpressed CelC protein was tested on cellulose-type substrates, the recombinant protein is able to degrade cellulose-type substrates, such as CM-cellulose, xylan, avicel, lichenan, and laminarin. Optimal temperature and pH for enzyme activity were found to be 50$^{\circ}C$ and pH 6.5, respectively.