• BMB Reports
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• 제31권2호
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• pp.144-148
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• 1998

A bifunctional catalase-peroxidase, designated catalase-2, of a UV resistant Deinococcus radiophilus was purified to electrophoretic homogeneity by both chromatographic and electrophoretic methods. Its molecular weight was 310 kDa and composed of a tetramer of 80 kDa subunits. The catalase-2 exerted its optimal activity at $30^{\circ}C$ and around pH 9. Its $K_m$ value for $H_{2}0_{2} $ was about 10 mM. It showed the typical ferric heme spectrum with maximum absorption at 403 nm which shifted to 419 nm in the presence of cyanide. The ratio of A40i' A2S0 was 0.48. Fifty percent inhibition of the enzyme activity was observed at $4.6{\times}10^{-6}$, $7.7{\times}10^{-6}$, and $3.0{\times}10^{-6}$ M of NaCN, $NaN_3$, and $NH_{2}OH$, respectively. The enzyme was thermostable and not sensitive to 3-amino-1,2,4-triazole. Treatment of the enzyme with ethanol-chloroform caused a partial loss (30%) of its activity. The catalase-2 was distinct from the Deinococcal bifunctional catalase-3 in a number of properties, particularly in its molecular structure and substrate affinity.

• 한국전자파학회논문지
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• 제15권1호
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• pp.68-72
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• 2004

InGaP/GaAs HBT공정을 이용하여 1.75 ㎓의 전압제어 발진기를 설계한다. 전압제어 발진기의 위상 잡음을 개선하기 위하여 저역 통과 필터의 특성을 가지는 새로운 잡음 제거 회로를 제안하고, 극 소형화를 위하여 FR-4 기판의 특수한 적층 구조를 이용한다. 제작된 전압제어 발진기의 주파수 변화 범위는 약 200 MHz이고, 위상 잡음은 120 KHz 옵？에서 -119.3 ㏈c/Hz이다. VCO 코어의 소비 전력은 공급 전원 2.8 V에서 11.2 ㎽이고, 출력 파워는 -2 ㏈m이다. FOM의 계산치는 191.7로써, 지금까지 발표된 FET나 HBT 전압제어 발진기보다 좋은 성능을 보인다. 완성된 전압제어 발진기의 크기는 3.266 mm ${\times}$ 3.186 mm로 극소형이다.

• KSBB Journal
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• 제14권3호
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• pp.365-370
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• 1999

To optimize the culture conditions for Beauveria bassiana 726, the effects of culture medium, pH, and temperature on mycelium and spore production were investigated. The optimum temperature and pH for the cultivation of B. bassiana 726 were 28 $^{\circ}C$ and 5.0, respectively. The optimized medium was composed of 1.0~2.0% total sugar from molasses, 0.5% corn steep liquor and 0.05% KH$_2$PO$_4$. In the cultivation of B. bassiana 726 with the optimum medium, the specific growth rate and substrate utilization were well-fitted with the proposed kinetic model in the shake flask and stirred tank reactor. When the fed-batch cultivation using carbon suorce, nitrogen source, and mineral salt as a feeding medium was compared with batch cultivation in stirred tank reactor, mycelium (12.7 g/L) and spore production (5.4$\times$$10^8/mL$) were enhanced up to 110% and 85%, respectively.

• 생물환경조절학회지
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• 제10권2호
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• pp.88-94
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• 2001

Ash ball 배지의 이화학적특성과 사용배지의 염류집적 및 제거효과를 펄라이트 및 입상암면과 비교하였다. ash ball의 가비중, 진비중, 공극율은 각각 0.93 g.$cm^{-3}$, 2.29 g.$cm^{-3}$, 40.6%, 59.4%로서 그중 가비중은 펄라이트 및 입상암면에 비해 현저히 높았고 가공율은 낮았다. 배지의 포화수분함량(saturation moisture capacity)은 ash ball이 52%, 펄라이트가 71%, 입상암면이 90%로 나타났고, 배수 1시간 후 수분율은 ahs ball이가 21%, 펄라이트가 27%, 입상암면이 80%로 낮아졌다. Ash ball의 입도별 수분율은 소립(3~5 mm)이 대립 (7~15mm)에 비해 5% 정도 높았다. Ash ball의 배드내 수분율은 수직 및 수평방향의 분포가 균일하여 수분확산성이 좋은 것으로 나타났다. ash ball의 pH는 7.6으로 약염기성을 나타내었다. 배지를 침지한 배양액의 pH는 7.6으로 약염기성을 나타내었다. 배지를 침지한 배양액의 pH는 다소 증가하는 경향을 보였으며 EC는 거의 변호가 없었으며, 배지내 무기이온의 흡착은 ash ball과 입상암면은 인산의 흡착이 비교적 많았다. 토마토 재배에 사용된 ash ball의 염류집적은 펄라이트와 비슷하였고 8회 정도의 침수처리로 배지표면에 흡착된 무기염을 대부분 제거할 수 있었다. 위의 결과로부터, ash ball 배지는 보수력은 다소 낮지만 통기성 및 수분확산성이 우수하여 배지내의 수분조절이 용이한 배지임을 알 수 있었다.

• 한국식품영양과학회지
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• 제24권3호
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• pp.355-361
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• 1995

Lipoprotein lipase(LPL) is an acylglycerol hydrolase and is the extrahepatic enzyme responsible for the hydrolysis of triglyceride-rich plasma lipoproteins. LPL has been isolated from bovine milk by affinity chromatography on heparin-sepharose in 2M NaCl, 5mM barbital buffer, pH 7.4. Para-nitrophenyl butyrate(PNPB) was used as a substrate for the determination of LPL activity. Molecular weight of LPL was 55KD on 10% SDS-PAGE. When the effects of heparin on LPL activation were compared, LPL activity of heparin added group increased approximately 5 times higher than that of heparin non-added groups. These results indicated that heparin involved in the stabilization of LPL structure that led to increase enzyme activity. Furthermore, LPL activity increased about 4 times compared to the absence of heparin at various pH. LPL was stabilized when heparin was added either low or high salt concentrations. With the presence of heparin, NaCl concentration did not affect LPL activity at pH range 6∼9.

• Biotechnology and Bioprocess Engineering:BBE
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• 제2권2호
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• pp.86-89
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• 1997

Epidermal growth factor(EGF) known as a urgastrone is a powerful mitogen with a wide variety of possibilities for medical usages. A mature EGF coding region was isolated from human prepro-EGF sequence by a conventional PCR and cloned into pQE vector in which the gene product was supposed to be expressed with 6$\times$His tag for the subsequent purification. The recombinant mature EGF was expressed in M15[Rep4], an Escherichia coli host strain, in amount of 30-40% of total proteins pressent in E. coli extract by the addition of isopropylthio-$\beta$-galactopyranoside (IPTG). The recombinant EGF purified using a Ni2+-NTA affinity colume chromatography was active in its ability to induce phosphorylation on tyrosine residues of several substrate proteins when murine NH3T3 and human MRC-5 fibroblast cells were stimulated with it. This work may provide the basic technology and information for the production of recombinant EGF.

• 생약학회지
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• 제22권2호
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• pp.101-111
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• 1991

Polyphenol oxidase(PPO) was purified from an extract of Puerariae Radix by ammonium sulfate fractionation followed by Sephadex G-150 column chromatography, which resulted in a 56-fold increase in specific activity. The enzyme was optimum of pH 6.5. The optimum temperature of enzymic reaction was about $40^{\circ}$. The enzyme was thermostable with a half-life equal to 32 min at $70^{\circ}$. Km values of the PPO for catechol and pyrogallol from Lineweaver Burk plots were $1.3{\times}10^{-2}M$, $1.16{\times}10^{-2}M$, respectively. The substrate specificity of the Puerariae Radix PPO showed high affinity toward pyrogallol. Reducing reagents such as cysteine, potassium metabisulfite, ascorbic acid, 2-mercaptoethanol completely inhibited the PPO activity at $10^{-2}M$ level. Linewear-Burk analysis of inhibition data revealed that the inhibition by cysteine, 2-mercaptoethanol, 4-nitrocatechol, potassium cyanide was competitive with Ki values of $4.3{\times10^{-2}M,\;0.73{\times}10^{-6}M,\;6.9{\times}10^{-6}M,\;6.4{\times}10^{-7}M$, respectively. The browning reaction by PPO was observed to decrease temporarily with the addition of sodium diethyl dithiocarbamate, a well known copper chelating agent. Among the divalent cations, $Cu^{2+}$ ion was strong activator on PPO and $Mn^{2+},\;Co^{2+}$ ions was effect on PPO activity. $Zn^{2+},\;Mg^{2+}$ ions was inhibitor on PPO.

• 한국분말재료학회지
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• 제29권4호
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• pp.283-290
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• 2022

A Cu-15Ag-5P filler metal (BCuP-5) is fabricated on a Ag substrate using a high-velocity oxygen fuel (HVOF) thermal spray process, followed by post-heat treatment (300℃ for 1 h and 400℃ for 1 h) of the HVOF coating layers to control its microstructure and mechanical properties. Additionally, the microstructure and mechanical properties are evaluated according to the post-heat treatment conditions. The porosity of the heat-treated coating layers are significantly reduced to less than half those of the as-sprayed coating layer, and the pore shape changes to a spherical shape. The constituent phases of the coating layers are Cu, Ag, and Cu-Ag-Cu3P eutectic, which is identical to the initial powder feedstock. A more uniform microstructure is obtained as the heat-treatment temperature increases. The hardness of the coating layer is 154.6 Hv (as-sprayed), 161.2 Hv (300℃ for 1 h), and 167.0 Hv (400℃ for 1 h), which increases with increasing heat-treatment temperature, and is 2.35 times higher than that of the conventional cast alloy. As a result of the pull-out test, loss or separation of the coating layer rarely occurs in the heat-treated coating layer.

• 한국환경과학회지
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• 제4권5호
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• pp.469-479
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• 1995

The increase of population and industrial activities had brought into eutrophication in the Nakdong river. A remarkable acceleration of eutrophication brought about serious problems for water supply. Therefore, for the purpose of conservation of water quality in the Nakdong river it is necessary to control nutrients. MBOD method was use to evaluate algal growth limiting factor and algal growth potential in the Nakdong river from June to August 1994. The modified biochemical oxygen demand(MBOD) depends on the amount of available inorganic nutrient and organic substrate during 5 day incubation in the dark at 2$0^{\circ}C$. The MBOD assay depends on inorganic nutrients such as P and N as well as reduced carbon and called the MBOD, the MBOD-P, and the MBOD-N, respectively. The results of bioassay by MBOD(Modified BOD) method showed that the MBOD, MBOD-P and MBOD-N value were found to be in the ranges of 3.8~96.0 mg$O_2$/l, 5.6~94.0 mg$O_2$/l and 42.0~220 mg$O_2$/l, respectively. And the the bioassay value was found to be the highest in Koryong area and the lowest in Waekwan area throughout the Nakdong river. The variations of MBOD-P and MBOD-N value showed similar tendencies to the variations of phosphorus and nitrogen value, respectively. By MBOD method, the relationships of MBOD, MBOD-P and MBOD-N value were MBOD ≒ MBOD-P 《 MBOD-N. The MBOD value was nearly equal to the MBOD-P value, and the MBOD-N value was 3 to 20 times more than the MBOD-P value, approximately. Therefore, in the Nakdong river, phosphorus was the limiting factor for algal growth during summer season. The algal growth potential as the concentration of chlorophyll-a in the summer was maximum 5 times more than standing crop as it.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2005년도 2005 Annual Meeting & International Symposium
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• pp.204-211
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• 2005

The technology of Solid-State-Fermentation (SSF) with corn straw by Pichia ohmeri T021 was studied in this article. After being crushed, the corn straw powder was added into vitriol solutions to hydrolysis, which the quality proportion of corn straw: water: vitriol (98%) is 20:80:1. The mixtures was incubated at 120$^{\circ}C$ for 1 hour, and the hydrolysis rate reached 19%. Following, the mixture was adjusted to pH 4.5 by sodium carbonate and added cellulase (25IFPU/g). The hydrolysis rate reached 15% after the mixture was incubated at 50$^{\circ}C$ for 25h. The mixture which hydrolysed by vitriol was inoculated by Pichia ohmeri T021 (5${\times}10^7$cell/g) and added cellulase (25 IFPU/g) at the same time. The ethanol yield reached 2.99g per 100 gram substrate after the fermenting grains was incubated at 33$^{\circ}C$, pH 4.5 for 5 days.