• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.2
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• pp.333-339
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• 2008

Korean ginseng (Panax ginseng C. A. Meyer) has been used as an important medicinal plant in the Orient for a long time. It has been claimed that ginseng has many beneficial bioactive effects on human health, such as antitumor, antistress, antiaging and enhancing immune functions. Red ginseng possibly have new ingredients converted during steaming and dry process from fresh ginseng. Kujeungkupo method which means 9 repetitive steaming and drying process was used for the processes of green tea, Polygonatum odoratum, and Rehmanniae radix preparata. In this study, ingredient conversion of ginseng by 9 repetitive steaming and drying process were investigated measuring conversion efficiency of brown materials, crude lipids, crude proteins and aromatic compounds. Brown materials, as an antioxidant, in red ginseng were produced through non-enzymatic reaction by heat. Repetitive steaming and drying treatments on ginseng root contiunously increased the content of brown materials and the chromaticity. Crude lipids were degraded by heat and converted into volatile aromatic ingredients. Crude lipids were degraded and decreased by 0.52% after the 5th and 7th. Crude proteins were also decomposed and converted to amino acid. Crude proteins after the 9th treatment were decreased by more than 85% as increased times of treatments. A bicyclogermacrene as aromatic material was decreased as increased treatment times, while but a aromatic caramel was increased.

• Journal of Microbiology and Biotechnology
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• v.6 no.5
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• pp.336-339
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• 1996

Glutaryl 7-aminocephalosporanic acid acylase of Pseudomonas sp. SY-77-1 was immobilized with oxiran acrylic beads for the production of 7-aminocephalosporanic acid (7-ACA) from glutaryl 7-aminocephalosporanic acid (GL 7-ACA). The immobilized enzyme maintained its activity at a constant level for 7 days, but lost 30$%$ of its activity after 20 days. Optimal reaction conditions for the synthesis of 7-ACA were found to be $30^{\circ}C$ and pH 8.0 using the immobilized enzyme. For the economic production of 7-ACA, substrate and enzyme concentrations were optimized to 60 mM and 0.5 g wet weight per 10 $m\ell$ of reaction volume, respectively. Under optimized conditions, 50 mM 7-ACA was produced from 60mM GL 7-ACA within 8 h, resulting in a conversion yield of 83$%$.

• Journal of Microbiology and Biotechnology
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• v.4 no.3
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• pp.204-209
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• 1994

The synthesis of N-(benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methylester (Z-APM), a precursor of aspartame, from N-(benzyloxycarbonyl)-L-aspartic acid (Z-Asp) and L-phenylalanine methylester hydrochlolide($L-PM\cdot HCI$) was investigated in a saturated-ethylacetate single phase system using immobilized thermolysin. Among the various supports tested, glyceryl-CPG was found to be most efficient for retaining enzyme activity. The enzyme immobilized onto glyceryl-CPG also showed the highest activity for Z-APM synthesis in saturated ethyl acetate. Z-APM conversion yield in saturated ethylacetate was half of that obtained in an ethyl acetate-buffer two-phase system under the same reaction conditions. However, as the mole ratio of $L-PM \cdot HCI$ to Z-Asp was increased to 4.0, the conversion yield reached 95 %. When continuous synthesis of Z-APM was canied out in a plug flow reactor (PFR) with 80 mM of L-PMㆍHCI and 20 mM of Z-Asp in saturated ethylacetate (pH 5.5), more than 95 % of Z-Asp was converted to Z-APM with a space velocity of 1.16 $hr^{-1} at 40^{\circ}C$. Although the operational stability in PFR was reduced rapidly, more than 80% of initial activity was maintained in CSTR even after a week of operation.

• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1927-1931
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• 2008

In this study, the enzymatic process for biodiesel production was optimized using a mixture of immobilized Rhizopus oryzae and Candida rugosa lipases. The optimal temperature and agitation speed for biodiesel production were $45^{\circ}C$ and 300 rpm, respectively. The optimal ratio of R. oryzae and C. rugosa lipases in the mixture was 3:1 (w:w). When 3 mmol of methanol was the initial reaction medium and 3 mmol of methanol was added every 1.5 h during biodiesel production, biodiesel conversion was over 98% at 4 h. In addition, when the immobilized lipase mixture was reused, biodiesel conversion exceeded 80% after 5 reuses.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.511-511
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• 2009

Lignocellulosic biomass is the most abundant organic material on earth and also promising raw material for bioenergy production. Agricultural residues in the process of bio-oil extraction, is an abundant and low-cost lignocellulosic material. The technology for conversion of lignocellulosic biomass resources to fuels and chemicals, such as ethanol, has been under development for decades. One of the well-studied technologies that are currently being commercialized is to use a dilute acid-catalyzed pretreatment followed by enzymatic hydrolysis and fermentation to produce ethanol. In this work, the dilute-acid hydrolysis of agricultural residues was optimized through the utilization of statistical experimental design. Evaluation criteria for optimization of the pretreatment conditions were based on high xylose recovery and low inhibitor contents in the hydrolyzates. The purpose of this study was to gain a more accurate understanding of the quantities of acid required for effective hydrolysis and the reactivity trade-offs with reaction time and temperature that will enable overall process optimization.

• Journal of Ginseng Research
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• v.38 no.1
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• pp.47-51
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• 2014

The transformation of ginsenoside Rb1 into a specific minor ginsenoside using Aspergillus niger KCCM 11239, as well as the identification of the transformed products and the pathway via thin layer chromatography and high performance liquid chromatography were evaluated to develop a new biologically active material. The conversion of ginsenoside Rb1 generated Rd, Rg3, Rh2, and compound K although the reaction rates were low due to the low concentration. In enzymatic conversion, all of the ginsenoside Rb1 was converted to ginsenoside Rd and ginsenoside Rg3 after 24 h of incubation. The crude enzyme (b-glucosidase) from A. niger KCCM 11239 hydrolyzed the ${\beta}$-($1{\rightarrow}6$)-glucosidic linkage at the C-20 of ginsenoside Rb1 to generate ginsenoside Rd and ginsenoside Rg3. Our experimental demonstration showing that A. niger KCCM 11239 produces the ginsenoside-hydrolyzing b-glucosidase reflects the feasibility of developing a specific bioconversion process to obtain active minor ginsenosides.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.501-506
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• 2019

New technology-driven biocatalysts are revolutionizing the biochemical industries. With maximum utilization of renewable feedstock, biocatalysts have been the basis for a major breakthrough. Lipases are the most widely established catalysts used for hydrolysis, esterification and transesterification reactions. In this research, a biochemical process that combines extraction of lipase enzyme from germinated wheat seeds and its application to valorize glycerol to acetins by esterification is presented. Acetins are among highly rated, value-added products derived from glycerol. The favorable conditions for the enzymatic conversion of glycerol were observed as glycerol to acetic acid molar ratio (1:5), reaction temperature ($40^{\circ}C$) and the amount of enzyme (20% v/v). 65.93% of glycerol conversion was achieved for duration of 15 h with the use of tert-butanol solvent. This method proposes to explore the viability of a biological route to convert glycerol derived from biodiesel industry to acetins with further streamlining.

• KSBB Journal
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• v.25 no.4
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• pp.337-343
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• 2010

It has been well known that organic solvents like t-butanol and n-hexane can protect lipases from the inhibition by short-chain alcohols in the enzymatic transesterification. However, use of the organic solvents should be minimized considering their negative effects on environment and human health. Therefore, use of the greener solvents has been pursued in various are as including the enzymatic biotranformation. In this study, the liquid carbon dioxide ($LCO_2$) was employed as an alternative media for the enzymatic transesterification of canola oil. The conversion in the $LCO_2$ was comparable with those in organic solvents and the supercritical carbon dioxide, and under optimum conditions, the value reached 99.7%. It is expected that this method can provide a new type of biodiesel production process with higher energy efficiency and lower environmental impact.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.9-15
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• 2015

The seaweed, Gracilaria verrucosa, was fermented to produce bioethanol. Optimal pretreatment conditions were determined to be 12% (w/v) seaweed slurry and 270 mM sulfuric acid at 121℃ for 60 min. After thermal acid hydrolysis, enzymatic saccharification was carried out with 16 U/ml of mixed enzymes using Viscozyme L and Celluclast 1.5 L to G. verrucosa hydrolysates. A total monosaccharide concentration of 50.4 g/l, representing 84.2% conversion of 60 g/l total carbohydrate from 120 g dw/l G. verrucosa slurry was obtained by thermal acid hydrolysis and enzymatic saccharification. G. verrucosa hydrolysate was used as the substrate for ethanol production by separate hydrolysis and fermentation (SHF). Ethanol production by Candida lusitaniae ATCC 42720 acclimated to high-galactose concentrations was 22.0 g/l with ethanol yield (Y_EtOH) of 0.43. Acclimated yeast to high concentrations of specific sugar could utilize mixed sugars, resulting in higher ethanol yields in the seaweed hydrolysates medium.

• Molecules and Cells
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• v.37 no.4
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• pp.322-329
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• 2014

N-acetylglucosamine kinase (GlcNAc kinase or NAGK; EC 2.7.1.59) is highly expressed and plays a critical role in the development of dendrites in brain neurons. In this study, the authors conducted structure-function analysis to verify the previously proposed 3D model structure of GlcNAc/ATP-bound NAGK. Three point NAGK mutants with different substrate binding capacities and reaction velocities were produced. Wild-type (WT) NAGK showed strong substrate preference for GlcNAc. Conversion of Cys143, which does not make direct hydrogen bonds with GlcNAc, to Ser (i.e., C143S) had the least affect on the enzymatic activity of NAGK. Conversion of Asn36, which plays a role in domain closure by making a hydrogen bond with GlcNAc, to Ala (i.e., N36A) mildly reduced NAGK enzyme activity. Conversion of Asp107, which makes hydrogen bonds with GlcNAc and would act as a proton acceptor during nucleophilic attack on the ${\gamma}$-phosphate of ATP, to Ala (i.e., D107A), caused a total loss in enzyme activity. The overexpression of EGFP-tagged WT or any of the mutant NAGKs in rat hippocampal neurons (DIV 5-9) increased dendritic architectural complexity. Finally, the overexpression of the small, but not of the large, domain of NAGK resulted in dendrite degeneration. Our data show the effect of structure on the functional aspects of NAGK, and in particular, that the small domain of NAGK, and not its NAGK kinase activity, plays a critical role in the upregulation of dendritogenesis.