• KSBB Journal
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• v.29 no.1
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• pp.1-8
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• 2014

Tyrosinases catalyze the hydroxylation of monophenolic compounds and the conversion of o-diphenols to oquinones. The enzymes are mainly involved in the modification of tyrosine into L-3,4-dihydroxyphenyl-alanine (L-DOPA) and DOPA/DOPAquinone-drived intermolecular cross-linking, which play the key roles of pigmentation to the cells. It is ubiquitously distributed in microorganisms, plants, and animals all around the nature world. They are classified as copper- containing dioxygen activating enzymes; two copper ions are coordinated with six histidine residues in their active sites and they are distinguished as met-, deoxy-, and oxy-form depending on their oxidative states. Natural extraction and recombinant protein approaches have been tried to obtain practical amounts of the enzymes for industrial application. Tyrosinases have been widely applied to industrial and biomedical usages such as detoxification of waste water containing phenolic compounds, L-DOPA as a drug of Parkinson's disease, biomaterials preparation based on the cross-linking ability and biosensors for the detection of phenolic compounds. Therefore, this review reports the mechanism of tyrosinase, biochemical and structural features and potential applications in industrial field.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.70-70
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• 2003

Active sites and substrate bindings of 1-aminoxyclopropane-1-carboxylate oxidase (MD-ACO1) catalyzing the oxidative conversion of ACC to ethylene have been determined based on site-directed mutagenesis and comparative modeling methods. Molecular modeling based on the crystal structure of Isopenicillin N synthase (IPNS) provided MD-ACO1 structure. MD-ACO1 protein folds into a compact jelly roll shape, consisting of 9 ${\alpha}$-helices, 10 ${\beta}$-strands and several long loops. The MD-ACO1/ACC/Fe(II)/Ascorbate complex conformation was determined from automated docking program, AUTODOCK. The MD-ACO1/Fell complex model was consistent with well known binding motif information (HIS177-ASP179-HIS234). The cosubstrate, ascorbate is placed between iron binding pocket and Arg244 of MD-ACO1 enzyme, supporting the critical role of Arg244 for generating reaction product. These findings are strongly supported by previous biochemical data as well as site-directed mutagenesis data. The structure of enzyme/substrate suggests the structural mechanism for the biochemical role as well as substrate specificity of MD-ACO1 enzyme.

• Proceedings of the EASDL Conference
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• 2004.10a
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• pp.13-30
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• 2004

There are two groups of significant functional constituents in sesame seeds on the whole; one is the vegetable oils and another is the anti-oxidative compounds. However, although high amounts of major fatty acids are synthesized in sesame seeds, their composition is unfavorable because the contents of alpha- and gamma-linolenic acid, the essential fatty acids, are very low or do not produced in sesame seeds. So, to increase these fatty acids in sesame seeds, one strategy is to overexpress their genes, ${\omega}$-3 fatty acid desaturase for alpha-linolenic acid and delta-6 fatty acid desaturase for gamma-linolenid acid, in them. Another molecular target is to enhance alpha-tocopherol, vitamin E, because its content is very low in sesame seeds. The enzyme, gamma-tocopherol methyltransferase, catalyzes the conversion of gamma-tocophero to alpha-tocopherol. Overexpression of this enzyme in sesame seeds could be also a good molecular breeding target. Reduction of phytic acid is also another molecular target in sesame seeds because phosphorus pollution may be caused by its high content in sesame seeds. Accordingly, to do so, one of target enzymes could be myo-inositol 1-phosphate synthase which is a key regulatory enzyme in the pathway of phytic aicd biosyntheses. In this lecture, a molecular strategy for development of value-added sesame crop is described in association with some results of our experiments involved in the molecular characterizations of the genes mentioned above.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.128-134
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• 2016

Due to the great development made in converting the shale gas into the more valuable products, research and commercialization for production technology of olefins like propylene, butenes, butadiene from light alkanes have been intensively investigated. Especially the technology using oxygen like oxidative dehydrogenation or selective hydrogen combustion to overcome thermodynamic limit of direct dehydrogenation conversion has been extensively studied and some cases of applying this technology to the plant scale was reported. In this review, we have categorized the technology into two parts; gas phase oxygen utilization technology and lattice oxygen utilization technology. The trends, results and future direction of the technology are discussed.

• Korean journal of food and cookery science
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• v.24 no.6
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• pp.729-734
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• 2008

The principal objective of this study was to assess the possibility of transforming platycodin glycosides using various strains of probiotic bateria and edible fungi. Among the experimental microorganisms assess herein, Aspergillus niger KCTC 6909 evidenced the highest level of platycodin glycoside hydrolysis during fermentation. Particularly in cases in which the organism was incubated in the presence of rhamnose and platycodins. In order to produce the enzyme from Aspergillus niger effectively, various incubation conditions were assessd in order to determine the optimal conditions. The cytotoxicity on V79-4 (Chinese- hamster lung fibroblasts, normal cells) of platycodin was reduced significantly after conversion (concentration on $500{\mu}g/mL$, $1000{\mu}g/mL$); DPPH radical scavenging activity before conversion was 35.05%, and was 57.44% afterward. We noted significantly higher conversion activity inhibiting oxidative degradation. In conclusion, these results indicate that the proper combination of food microorganisms -and fermentation conditions can result in an increase in the glycoside hydrolysis of platycodin the resultant products of which reduce cytotoxicity- and increase anti-oxidant activity.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.391-396
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• 2015

To investigate the effect of the catalyst synthesis method on the oxidative dehydrogenation (ODH) of nbutenes, $BiFe_{0.65}MoP_{0.1}$ oxide catalysts were prepared with various synthesis methods such as co-precipitation, citric acid method, hydrothermal method, and surfactant templated method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $NH_3/1$-butene-temperature programmed desorption ($NH_3/1$-butene-TPD) to correlate with catalytic activity in ODH reaction. Among the catalysts studied here, $BiFe_{0.65}MoP_{0.1}$ oxide catalyst prepared with co-precipitation method marked the highest activity showing 1-butene conversion, 79.5%, butadiene selectivity, 85.1% and yield, 67.7% after reaction for 14 h. From the result of $NH_3$-TPD, the catalytic activity is closely related to the acidity of the $BiFe_{0.65}MoP_{0.1}$-x oxide catalyst and acidity of the $BiFe_{0.65}MoP_{0.1}$ oxde catalyst prepared with co-precipitation method was higher than that of other catalysts. In addition, combined with the 1-butene TPD, the higher catalytic activity is closely related to the amount of weakly adsorbed intermediate (< $200^{\circ}C$) and the desorbing temperature of strongly adsorbed intermediates (> $200^{\circ}C$).

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.12
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• pp.1914-1922
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• 2019

Objective: The study was conducted to evaluate the effect of stocking density and alphalipoic acid (ALA) on the growth performance, feed utilization, carcass traits, antioxidative ability and immune response of broilers. Methods: A total of 1,530 22-day-old male broilers (Arbor Acres) with comparable body weights ($731.92{\pm}5.26$) were placed into 18 cages ($2.46{\times}2.02m$) in groups of 75 birds ($15birds/m^2$, $37.5kg/m^2$; low stocking density [LD]), 90 birds ($18birds/m^2$, $45.0kg/m^2$; high stocking density [HD]) and 90 birds with 300 mg/kg ALA added to the basal diet ($18birds/m^2$, $45.0kg/m^2$; HD+ALA, high stocking density+${\alpha}$-lipoic acid); each treatment was represented by 6 replicates. The experimental period was 3 weeks. Results: The results showed that the high stocking density regimen resulted in a decreased growth, feed conversion ratio, carcass weight, thigh yield and bursa weight relative to body weight (p<0.05) on d 42. The abdominal fat yield in the HD+ALA group was lower (p = 0.031) than that of the LD group at 42 d. The superoxide dismutase and glutathione peroxidase activities in serum were increased, and malondialdehyde content decreased after adding ALA product (p<0.05) on d 42. Additionally, the serum concentrations of immunoglobulin A (IgA) and IgG were decreased (p<0.05) and the level of diamine oxidase was higher (p<0.01) in the HD group on d 42. Conclusion: The high stocking density significantly decreased broiler growth performance, feed utilization and carcass traits, increased physiological and oxidative stress and induced intestinal mucosal injury. The supplementation of ALA product in broiler diet at 300 mg/kg may reduce the adverse effects of high stocking density-mediated stress by maintaining the antioxidant system and humoral immune system.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.8
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• pp.1164-1170
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• 2008

In this study, the effects of propolis and vitamin C (L-ascorbic acid) supplementation in diets were investigated on feed intake (FI), body weight (BW), body weight gain (BWG), feed conversion rate (FCR) and digestibility and on egg production and qualities (weight, mortality, shell thickness) in laying hens exposed to heat stress. A total of 150 Hyline White Leghorn, aged 42 weeks, hens was divided into five groups of 30 hens. Chicks were randomly divided into 1 positive control, 1 control and 3 treatment groups. The chicks were kept in cages in temperature-controlled rooms at $22^{\circ}C$ for 24 h/d (positive control, Thermoneutral, TN group) or $34^{\circ}C$ for 9 h/d from 08.00-17.00 h followed by $22^{\circ}C$ for 15 h (control, heat stress, HS group) and fed a basal diet or basal diet supplemented with vitamin C (250 mg/kg of L- ascorbic acid/kg of diet) or two levels of propolis (2 and 5 g of ethanol extracted propolis/kg of diet). Increased FI (p<0.05) and improvement in FCR (p<0.05), hen day egg (p<0.05) and egg weight (p<0.05) were found in Vitamin C and propolis-supplemented laying hens reared under heat stress conditions. Mortality rate was higher in the control group than TN, vitamin C and propolis groups (p<0.05). Digestibility of dry matter, organic matter, crude protein and ether extract improved with increasing of both dietary vitamin C and propolis (p<0.05). Vitamin C or propolis supplementation did not affect either the percentage shape index, yolk index or haugh unit and albumen index (p>0.05). However, the egg shell thickness and egg shell weight appeared to be increased in Vitamin C and propolis groups in comparison to HS group birds (p<0.05). In conclusion, dietary supplementation of laying hens with anti-oxidants (vitamin C and propolis) can attenuate heat stress-induced oxidative damage. These positive effects were evidenced by increased growth performance and digestibility, improvement of egg shell thickness and egg weight in comparison to non-supplemented birds. Moreover, supplementation with propolis (5 g/kg diet) was the most efficient treatment.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.11
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• pp.1614-1621
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• 2013

The aim of this study was to investigate the effects of graded levels of montmorillonite, a constituent of clay, on performance, hematological parameters and bone mineralization in weaned pigs. One hundred and twenty, 35-d-old crossbred pigs (Duroc${\times}$Large White${\times}$Landrace, $10.50{\pm}1.20$ kg) were used in a 28-d experiment and fed either an unsupplemented corn-soybean meal basal diet or similar diets supplemented with 0.5, 1.0, 2.5 or 5.0% montmorillonite added at the expense of wheat bran. Each treatment was replicated six times with four pigs (two barrows and two gilts) per replicate. Feed intake declined (linear and quadratic effect, p<0.01) with increasing level of montmorillonite while feed conversion was improved (linear and quadratic effect, p<0.01). Daily gain was unaffected by dietary treatment. Plasma myeloperoxidase declined linearly (p = 0.03) with increasing dietary level of montmorillonite. Plasma malondialdehyde and nitric oxide levels were quadratically affected (p<0.01) by montmorillonite with increases observed for pigs fed the 0.5 and 1.0% levels which then declined for pigs fed the 2.5 and 5.0% treatments. In bone, the content of potassium, sodium, copper, iron, manganese and magnesium were decreased (linear and quadratic effect, p<0.01) in response to an increase of dietary montmorillonite. These results suggest that dietary inclusion of montmorillonite at levels as high as 5.0% does not result in overt toxicity but could induce potential oxidative damage and reduce bone mineralization in pigs.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.260-260
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• 1994

Mammalian pyruvate dehydrogenase complex(PDC) enzyme consists of multiple oopies of three major oligomeric enzymes-El, E2 E3. And protein X is one of the enzymatic constituents which is tightly bound to E2 subunit This complex enzyme is responsible for the oxidative decarboxylation of pyruvate producing of acetyl CoA which is a key intermediate for the entry of carbohydrates into the TCA cycle for its complete metabolic conversion to CO$_2$. And the overall activity of the complex enzyme is regulated via covalent nodification of El subunit by a El specific phosphatase ad kinase. Protein X has lipoyl moiety that undergoes reduction and acetylation during ezymatic reaction and has been known h be involved in the binding of E3 subunit to E2 core and in the regulatory activity of kinase. The purification of protein X has not been achieved majorly because of its tight binding to E2 subunit The E2-protein X subcomplex was obtained by the established methods and the detachment of protein X from E2 was accomplished in the 0.1M borate buffer containing 150mM NaCl. During the storage of the subcomplex in frozen state at -70$^{\circ}C$, the E2 subunit was precipitated and the dissociated protein X was obtained by cntrifegation into the supernatant The verification of protein X was accomplished by (1)the migration on SDS-PAGE, (2)acetylation by 〔2$\^$-l4/C〕 pyruvate, and (3)internal amino acid sequence analysis of tryptic digested enzyme.