• BMB Reports
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• 제32권3호
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• pp.239-246
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• 1999

A tripeptidase (PepT) was purified to homogeneity from Bacillus subtilis through four sequential chromatographies including DEAE-Sepharose ion exchange, hydroxylapatite, mono-Q FPLC ion exchange, and Superose-12 FPLC gel filtration. The apparent molecular mass of the enzyme was 49,200 Da and 51,400 Da as determined by sodium dodecylsulfatepolyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography, respectively, and the enzyme exists in a monomeric form. The physicochemical properties of the enzyme were as follows: optimum pH at 7.5, optimum temperature at $60^{\circ}C$, and pI at 4.9. The $K_m$ and $V_{max}$ values of the enzyme were 4.3 mM and 2.5 mmol/min/mg, respectively, with MetAla-Ser as substrate. The B. subtilis PepT requires $Co^{2+}$ ion(s) for activation, while it is inactivated by EOTA and 1,10-phenanthroline, suggesting that it is a metalloprotein. The enzyme was not inhibited by any of serine protease, aspartic protease, or leucine aminopeptidase inhibitors. The enzyme showed comparable activities towards four different substrates including Met-Ala-Ser, Leu-Gly-Gly, Leu-Ser-Phe, and Leu-Leu-Tyr. The amino terminal sequence of PepT determined by Edman degradation was found to be MKEEIIERFTTYVXV and turned out to be identical to that of PepT deduced from a cloned B. subtilis pepT.

• 한국식품영양과학회지
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• 제25권4호
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• pp.687-694
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• 1996

한국산 겨자에서 myrosinase를 분리 및 정제하고, 이들의 효소학적 특성을 조사한 결과는 다음과 같다. 겨자 myrosinase를 DEAE-cellulose, Concanavalin A-Sepharose 및 FPLC Soporose 6 칼럼을 이용하여 분리 및 정제하였을 때 적어도 3개의 이성효소가 존재하는 것으로 나타났으며, Myrosinase II-2의 최종 비활성도는 57.lunits/mg, 정제도는 약 248배였다. SDS-PAGE상에서 myrosinase(II-2)의 단일밴드를 확인한 결과, 그 분자량은 약 67KD로 추정 되었다. 최적 pH는 phosphate 및 Tris-HCI 완충액에서 7.0이 가장 활성이 높았고, 그 효소는 pH 7.0에서 안정하였으며, 최적 활성을 나타내는 온도는 $37^{\circ}C$ 부근이었고, $40^{\circ}C$ 이상에서는 비교적 불안정하게 나타났다. Ascorbic acid의 영향은 1mM에서 가장 안정하였으며, 그 이상의 농도에서는 변화가 없었다. 망간과 마그네슘 및 나트륨은 효소활성을 촉진시키는 것으로 나타났으며 구리, 수은 및 철 이온은 약간 저해하였다. Ascorbic acid analogue 중 dehydroascorbic acid는 효소 활성을 저해하였으며, 나머지 것들은 거의 영향을 미치지 않았다. 2-Mer-captoethanol과 dithiothreitol과 같은 환원제는 효소활성을 억제하였으나 이들과 ascorbic acid를 함께 첨가 하였을 때는 활성이 다소 증가하였다.

• 한국작물학회지
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• 제41권4호
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• pp.456-464
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• 1996

밀의 영양체 저장탄수화물인 fructan의 대사에 관련된 fructan exohydrolase(FEH) 효소의 특성을 구명하기 위해 FEH를 밀의 줄기와 엽초에서 정제, 실험한 결과를 요약하면 다음과 같다. 1. FEH의 분자량은 63.7kD이었으며, pH 5.5와 3$0^{\circ}C$에서 최고의 활성을 보였다. 2. FEH의 $K_{m}$ 과 $V_{max}$는 fructan의 크기에 따라 각각 10~37mM, 5g~179mM로 변이를 보였으며, tetrasaccharide가 본 실험에서 사용된 기질 중에서 가장 낮은 $K_{m}$ 과 $V_{max}$를 보였다. 3. 밀의 FEH는 $eta$(2 $\longrightarrow$1)로 연결된 fructan에 대하여 기질 특이성을 보였으며 $\beta$(2 $\longrightarrow$6) fructan과 sucrose는 분해할 수 없었다.

• 한국토양비료학회지
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• 제44권1호
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• pp.67-77
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• 2011

Heavy metal remediation in shooting range soil is a challenge over the world. The excessive Pb accumulation in the soil can deteriorate soil quality and fertility. The objectives of this research were to evaluate the efficiency of biochar (BC) in improving the physicochemical and biological properties of the soil and to evaluate its effect on Pb availability in a military shooting range soil. Sandy loam soil was collected from shooting range of Gyeonggi Province, South Korea and was incubated for 30 days with different application rates (0-30% w $w^{-1}$) of BC. The results showed that the addition of BC increased aggregate stability, nitrogen (N) and phosphorus (P) contents, and enzyme activities in soil. Sequential extraction showed that residual and organic bound fractions in the soil amended with BC increased by 33.1 and 16.7%, respectively, and the exchangeable fraction decreased by 93.7% in the soil amended with BC, compared to the unamended soil. We concluded that the application of BC could not only improve physicochemical and biological soil qualities but also stabilize Pb in a shooting range soil.

• 대한전자공학회논문지
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• 제25권11호
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• pp.1350-1357
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• 1988

독립적인 nitridation step이 포함된 급속 열처리 공정을 이용하여 125-180A 두께의 이중 절연박막을 단결정 실리콘 상에 형성하였다. HCl 가스의 첨가량과 공정시간의 변화에 따른 박막 특성의 변화를 고찰하였고, 이에 따른 박막의 전기적 특성을 관찰하였다. HCl 가스의 첨가에 의해 초기의 산화막 두께의 성장은 현저하게 나타났으나, nitridation 후의 박막두께의 변화는 10A 이하로 매우 저조하였다. 이중 절연박막의 항복전압은 HCl 가스의 첨가량에 비례하여 점차 증가하였고, 절연강도는 furnace나 독립적인 nitridation step이 포함되지 않은 급속 열처리 공정으로 형성한 같은 두께의 박막에 비해 높은 것으로 분석되었다.

• 천문학회보
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• 제41권2호
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• pp.54.1-54.1
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• 2016

Stellar wind and radiation pressure from massive stars can trigger the formation of new generation of stars. The sequential age distribution of stars, the morphology of cometary globules, and bright-rimmed clouds have been accepted as evidence of triggered star formation. However, these characteristics do not necessarily suggest that new generation of stars are formed by the feedback of massive stars. In order to search for any physical connection between star forming events, we have initiated a study of gas and stellar kinematics in NGC 1893, where two prominent cometary nebulae are facing toward O-type stars. The spectra of gas and stars in optical and near-infrared (NIR) wavelength are obtained with Hectochelle on the 6.5m MMT and Immersion GRating INfrared Spectrograph on the 2.7m Harlan J. Smith Telescope at McDonald observatory. In this study, the radial velocity field of gas across the cluster is investigated using $H{\alpha}$ and [N II] ${\lambda}$ 6584 emission lines, and that of the cometary nebula Sim 130 is also probed using 1-0 S(1) transition line of $H_2$. We report a distinctive velocity field of the cometary nebulae and many ro-vibrational transitions of $H_2$ even at high energy levels in the NIR spectra. These properties indicate the interaction between the cometary nebulae and O-type stars, and this fact can be a clue to triggered star formation in NGC 1893.

• 자원환경지질
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• 제24권4호
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• pp.435-446
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• 1991

Ductile shear zones developed in Jurassic granites in the Yonggwang area show NE trend at the eastern part and nearly EW trend at the western part, respectively. Judged from shear sense indicators, they have resulted from dextral strike-slip movement. The intersection of both trends is thought to be due to the truncation and offset of NE shear zone Chonju Shear zone by the brittle Yonggwang fault which runs in near EW direction with sinistral movement sense. The simple shear deformation was predominate through the deformation in this ductile shear zone. Based on this deformation mechanism, the shear strain (${\gamma}$) estimated in domain 1 increases from 0.14 at the shear zone margin to 9.41 toward the center of shear zone. Total displacement obtained only from this measured section(JK 59 to JK14) appecars to be 1434.5 meters. The sequential development of microstructures can be divided into three stages; weakly-foliated, well-foliated and banded-foliated stages. In the weakly-foliated stage dislocation glide mechanism might be predominant. In the well-foliated stage grain boundary migration and progressive misorientation of subgrains was remarkable during dynamic recovery and recrystallization. In the banded-foliated stage grain boundary sliding and microfracturing mechanisms accompanied with crushing and cracking were marked. According to strain analysis from quartzites of the metasedimentary rocks, strain intensity (${\gamma}$) of the samples within the ductile shear zone ranges from 2.7 to 5.7, while that of the samples out of the ductile shear zone appears to be about 1.7.

• Food Science and Biotechnology
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• 제18권2호
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• pp.570-573
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• 2009

The debranching enzyme of Nostoc punctiforme (NPDE) is a novel enzyme that catalyzes the hydrolysis of $\alpha$-1,6-glycosidic linkages in starch, followed by the sequential hydrolysis of $\alpha$-1,4-glycosidic linkages. The debranching activity of NPDE is highly specific for branched chains with a degree of polymerization (DP)>8. Moreover, the rate of hydrolysis of $\alpha$-1,4-linkages by NPDE is greatly enhanced for maltooligosaccharides (MOs) with a DP>8. An analysis of reaction mixtures containing various starches revealed the accumulation of maltooctaose (G8) with glucose and maltose. Based on the novel enzymatic properties of NPDE, an MO mixture containing more than 60% G8 with yield of 18 g G8 for 100 g starch was prepared by the reaction of NPDE with soluble starch, followed by ethanol precipitation and gel permeation chromatography (GPC). The yield of the G8-rich mixture was significantly improved by the addition of isoamylase. In summary, a 4-step process for the production of a G8-rich mixture was developed involving the enzymatic hydrolysis of starch by NPDE.

• 한국자원식물학회지
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• 제19권1호
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• pp.68-75
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• 2006

유망 야생화의 하나인 구절초의 생육에 적합한 배양토를 구명하기 위해 무기재료로서 버미큘라이트, 펄라이트, 암쇄토, 모래, 밭토양을 사용하고 유기물원으로서 피트모스, 부염, 퇴비를 혼합한 배양토를 조성하여 구절초의 생육을 조사한 결과 다음과 같다. 구절초의 생육은 유기물원으로 부엽이 들어간 배양토에서 피트모스나 퇴비를 혼합한 것에 비해 현저히 양호한 것으로 나타났으며 시험 후 배양토의 이화학성 분석 결과 부엽과 피트모스를 사용한 배양토의 화학성은 모든 성분에 있어서 유사한 경향을 나타냈으나 퇴비를 사용한 처리에서는 pH가 ($8.6{\sim}8.9$)로 매우 상승하였고 인산의 함량이 ($237{\sim}1158\;mg/kg$)로 높아져 구절초의 생육을 불량하게 하는 원인이 된 것으로 판단되었다. 피트모스는 화학성분 조사 결과로서는 부엽과 유사한 것으로 나타났으나 양분의 공급 능력에서 부엽에 미치지 못하여 구절초의 생육이 불량하였던 것으로 생각된다. 구절초의 생육에 대한 통계처리 결과를 살펴보면 구절초의 배양토에 있어서 부엽을 유기물원으로 혼합한 상토가 피트모스나 퇴비에 비해 유의성 있는 생육의 증가를 보여 주었다. 부엽을 사용한 VPL, SaVPL, SVPL, UVPL 처리 간에 있어서도 VPL과 UVPL처리가 SaVPL 및 SVPL에 비해 유의성 있는 생육차이를 보였다. 피트모스를 혼합한 처리들과 퇴비를 혼합한 처리들 사이에는 피트모스 처리들이 퇴비에 비해 생육이 양호한 경향을 보였으나 통계적으로는 뚜렷한 경향을 보이지 못하였다.

• 한국축산식품학회지
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• 제39권6호
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• pp.966-979
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• 2019

Muscle-based by-products are often undervalued although commonly reported having a high amount of natural bioactive peptides. In this study, elastin was isolated from the protein of broiler hen skin while its hydrolysate was prepared using Elastase. Assessment of antioxidative properties of elastin-based hydrolysate (EBH) was based on three different assays; 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical and metal chelating ability. The EBH was purified further using ultrafiltration, gel filtration and Reverse- Phase High-Performance Liquid Chromatography (RP-HPLC). The IC₅₀ of ABTS radical activities for EBH were decreased as EBH further purified using ultrafiltration (EBH III; 0.66 mg/mL)>gel filtration (EB-II; 0.42 mg/mL)>RP-HPLC (EB-II4; 0.12 mg/mL). The sequential identification of the peptide was done by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/ TOF-MS) of the potent fractions obtained from RP-HPLC (EB-II4). The presence of hydrophobic amino acids (Val and Pro) in the peptide sequences could potentially contribute to the high antioxidant activity of EBH. The sequences GAHTGPRKPFKPR, GMPGFDVR and ADASVLPK were identified as antioxidant peptides. In conclusion, the antioxidative potential from poultry skin specifically from elastin is evident and can be explored to be used in many applications such as health and pharmaceutical purposes.