• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1904-1911
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• 2006

The cell-free extracts of 250 yeasts were screened for their in vitro anti-angiogenic activity, to develop a new cancer metastasis inhibitor. Saccharomyces cerevisiae K-7 was selected as the producer of the anti-angiogenic agent, because it had the highest anti-angiogenic activity. The anti-angiogenic agent was produced maximally from hydrolysates of Saccharomyces cerevisiae K-7, when the yeast was cultured in yeast extract-peptone-dextrose medium at 30$^{\circ}C$ for 24 h, and cell-free extracts were than digested with pepsin for 4 h at 37$^{\circ}C$. The anti-angiogenic agent was further purified by ultrafiltration, Sephadex G-25 gel permeation chromatography and reverse-phase HPLC, and the anti-angiogenic activity of the final purified preparation was 72.7% at 10 $\mu$M/egg. The purified anti-angiogenic agent was found to originate from the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) molecule of Saccharomyces cerevisiae K-7, and its peptide sequence was Val-Ser-Trp-Tyr-Asp-Asn-Glu-Tyr-Gly-Tyr-Ser-Thr-Arg-Val-Val-Asp. In the MTT assay, the shape of the HT-l 080 cell was clearly changed to a circular type at 0.2 mM purified anti-angiogenic agent. This result indicated that the growth of the HT-I080 cell was significantly inhibited at 0.2 mM of the purified anti-angiogenic agent. The MMP activity of the treated HT-l080 cells was not affected, evidenced by the gelatin zymography, indicating that the anti-angiogenic mechanism of the purified anti-angiogenic agent is not mediated through MMP activity.

• Journal of Microbiology and Biotechnology
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• 제22권9호
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• pp.1253-1257
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• 2012

A gene (acas) designated as ${\alpha}$-amylase was cloned from Arthrobacter chlorophenolicus A6. The multiple amino acid sequence analysis and functional expression of acas revealed that this gene really encoded an amylosucrase (ASase) instead of ${\alpha}$-amylase. In fact, the recombinant enzyme exhibited typical ASase activity by showing both sucrose hydrolysis and glucosyltransferase activities. The purified enzyme has a molecular mass of 72 kDa and exhibits optimal hydrolysis activity at $45^{\circ}C$ and a pH of 8.0. The analysis of the oligomeric state of ACAS with gel permeation chromatography revealed that the ACAS existed as a monomer.

• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1021-1025
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• 2011

A Bacillus subtilis strain was isolated from the intestine of Sebastiscus marmoratus (scorpion fish) that was identified as Bacillus subtilis CH2 by morphological, biochemical, and genetic analyses. The chitosanase of Bacillus subtilis CH2 was best induced by fructose and not induced with chitosan, unlike other chitosanases. The strain was incubated in LB broth, and the chitosanase secreted into the medium was concentrated with ammonium sulfate precipitation and purified by gel permeation chromatography. The molecular mass of the purified chitosanase was detected as 29 kDa. The optimum pH and temperature of the purified chitosanase were 5.5 and $60^{\circ}C$, respectively. The purified chitosanase was continuously thermostable at $40^{\circ}C$. The specific acitivity of the purified chitosanase was 161 units/mg. The N-terminal amino acid sequence was analyzed for future study.

• 대한화장품학회지
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• 제23권2호
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• pp.48-62
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• 1997

천연 고분자인 키토산의 1차 아민기를 아질산나트륨염에 의해 환원 말단에 알데히드기를 갖는 키토산 올리고사카라이드를 얻었으며, 이를 수소화붕소산나트륨으로 환원하여 수산기로 전환하였다. 얻어진 키토산 올리고사카라이드의 평균 중합도는 겔투과 크로마토그라피를 통해 약 2로 나타났으며, 키토산에 비해 친수성 용매에 대한 용해성이 매우 높게 나타났다. 보습효과를 글리세린과 비교 측정한 결과 키토산 올리고사카라이드는 어느 정도 수분을 보유할 수 있는 능력은 있으나 글리세린에 비하여 약한 것으로 나타났다. 피부의 섬유아세포 증식 실험결과1$\times$10-3 ~ 1$\times$10-4%농도에서 115 ~ 125%의 세포증식 효과를 보였다. 키토산 올리고사카라이드에 아실클로라이드를 반응시켜 얻은 N, N-디아실, O-아실 키토산 올리고사카라이드는 액정을 형성하였으며, 높은 결정성을 보였다. 또한 유동파라핀, 에스테르형 오일 성분 등에 대한 용해성이 우수하여 화장품용 유성성분으로서의 가능성을 나타내었다.

• 폴리머
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• 제25권6호
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• pp.803-810
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• 2001

새로운 개념의 초분지형 비선형 광학 고분자 (PE-Azo/Hyper)를 AB$_2$형의 기능기를 가지는 단량체 4-[N,N-bis(hydroxyethyl)amino-4'-formyl]azobenzene (CHO-DOH)으로부터 Knoevenagel 축중합 반응을 통하여 합성하였다. 겔크로마토그래피상에서 폴리스티렌을 기준시료로 측정된 중합체의 무게평균분자량은 M$_{w}$ =61,800 (M$_{W}$ /M$_{n}$=1.86)이었고 중합체의 용해도를 조사한 결과 1-methyl-2-pyrrolidinone, N,N-dimethylformamide 등의 반양자성극성 유기용매에 잘 녹았으며 따라서 이들 용매를 이용하여 양질의 박막성형이 가능하였다. 또한 열시차 분석법으로 중합체 PE-Azo/Hvper의 열적 성질을 조사한 결과 녹는점이 관찰되지 않아 무정형으로 판명되었으며 유리 전이 온도는 $121^{\circ}C$로 나타났다. 폴링에 의하여 극성 배향된 중합체 박막의 2차 비선형 계수를 Nd : YAG 레이저 (1064 nm)를 이용하여 Maker fringe 방법으로 측정한 결과 $d_{33}$= 25.4 pm/V로 비교적 높은 값을 나타내어 초분지형 고분자에서도 극성배향이 이루어져 비선형성이 발현됨을 관찰할 수 있었다.

• 폴리머
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• 제33권5호
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• pp.458-462
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• 2009

본 연구에서는 순차적 음이온 및 개환중합반응을 통해 ABC 형태의 폴리스티렌-폴리에틸렌옥사이드-폴리락티드 블록공중합체를 성공적으로 합성하였다. 우선, 첫번째 블록인 폴리스티렌을 합성하기 위해서, 사이클로헥산 용매에서 스티렌/이차-부틸리튬을 각각 단량체/개시제로 사용하여 음이온중합(anionic polymerization)을 수행하였고, 이후 고분자 말단을 수산기로 전환시키기 위해, 에틸렌옥사이드를 첨가하였다. 다음 단계로 포타슘 나프탈레나이드(potassium naphthalenide)를 이용하여 폴리스티렌 말단 수산기의 수소를 제거하여, 거대개시제인 PS-$O^-K^+$를 제조하였다. 준비된 거대 개시제에 정량된 에틸렌옥사이드를 첨가하여, 음이온중합을 수행하였다. 폴리락티드 블록을 도입시키는 개환중합의 경우, THF 용매에서 트리에틸알루미늄(triethylaluminum)/피리딘(pyridine)시스템을 이용하여 PS-b-PEO-$AlEt_2$ 형태의 거대개시제를 형성한 후, $90^{\circ}C$에서 중합을 수행하였다. 합성된 블록공중합체를 수소핵자기공명법 및 겔침투크로마토그래피 방법을 통해 조사한 결과, 잘 정의된 분자량 및 낮은 분자량 분포를 나타냄을 확인할 수 있었다.

• 폴리머
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• 제37권3호
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• pp.332-341
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• 2013

H-shaped amphiphilic pentablock copolymers $(PSt)_2-b-PCL-b-PEO-b-PCL-b-(PSt)_2$ was synthesized via chemoenzymatic method by combining enzyme-catalyzed ring-opening polymerization (eROP) of ${\varepsilon}$-caprolactone (${\varepsilon}$-CL) and atom transfer radical polymerization (ATRP) of styrene. By this process, we obtained copolymers with controlled molecular weight and low polydispersity. The structure and composition of the obtained copolymers were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and infrared spectroscopy analysis (IR). The crystallization behavior of the copolymers was analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The crystallization behavior of the H-shaped block copolymers demonstrated a PCL dominate crystallization. The self-assembly behavior of the copolymers was investigated in aqueous media. The hydrodynamic diameters of the copolymer micelles in aqueous solution were measured by dynamic light scattering (DLS). The morphology of the copolymer micelles was observed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The hydrodynamic diameters of spherical micelles declined gradually with the increase of the hydrophobic chain lengths of the copolymers. The critical micelle concentration (CMC) values were determined from fluorescence emission, and it was found that the CMCs decreased with an increase of PSt hydrophobic block lengths.

• 공업화학
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• 제31권3호
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• pp.284-290
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• 2020

Energetic thermoplastic elastomers (ETPEs) based on glycidyl azide polymer (GAP) and carboxylated GA copolymers [GAP-ETPE and poly(GA-carboxylate)-ETPEs] were synthesized using isophorone diisocyanate (IPDI), dibutyltin dilaurate (DBTDL), 1,4-butanediol (1,4-BD), and soft segment oligomers such as GAP and poly(GA-carboxylate). The synthesized GAP-ETPE and poly(GA-carboxylate)-ETPEs were characterized by Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), universal testing machine (UTM), calorimetry and sensitivity towards friction and impact. DSC and TGA results showed that the introduction of carboxylate group in GAP helped to have better thermal properties. Glass transition temperatures of poly(GA-carboxylate)-ETPEs decreased from -31 ℃ to -33 ℃ compared to that of GAP-ETPE (-29 ℃). The first thermal decomposition temperature in poly(GA_0.8-octanoate_0.2)-ETPE (242 ℃) increased in comparison to that of GAP-ETPE (227 ℃). Furthermore, from calorimetry data, poly(GA-carboxylate)-ETPEs exhibited negative formation enthalpies (-6.94 and -7.21 kJ/g) and higher heats of combustion (46713 and 46587 kJ/mol) compared to that of GAP-ETPE (42,262 kJ/mol). Overall, poly(GA-carboxylate)-ETPEs could be good candidates for a polymeric binder in solid propellant due to better energetic, mechanical and thermal properties in comparison to those of GAP-ETPE. Such properties are beneficial to application and processing of ETPE.

• International Journal of Industrial Entomology and Biomaterials
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• 제7권2호
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• pp.165-173
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• 2003

Cytokines represent an essential part of the innate immune response in mammals. Recently, several studies have reported the presence of cytokine-like activities and molecules in the invertebrates such as echinoderms, tunicates, mollusks and insects. In our serial study, we investigated presence of cytokines in the silkworm, Bombyx mori, infected with several immune inducers. Western blotting analysis using rabbit anti-human cytokines showed the presence of IL-6-like molecule in the hemolymph collected at 8 and 24 hrs after infection with peptidoglycan and oligodeoxynucleotide, and the molecular weight of the proteins was ∼45 kDa. We attempted to isolate the molecule by gel permeation HPLC, anion exchange chromatography, ultra centrifugation, and immuno-dot-blot assay, but until now the effort was not much successful yet. It, however, does not appear that the IL-6-like molecule in the silkworm larvae is a mere experimental artifact happened by Western blotting analysis. Instead, further experiment on this subject probably will provide us more fruitful result as detected in other invertebrates including insects.

• Journal of the Korean Wood Science and Technology
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• 제39권1호
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• pp.86-94
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• 2011

열분해 온도와 체류시간을 달리하며 급속 열분해 공정을 통해 얻어진 백합나무 바이오오일로부터 분말 형태의 열분해리그닌(pyrolytic lignin)을 회수하였다. 바이오오일을 구성하고 있는 열분해리그닌의 특성을 이해하고 급속 열분해 실험 조건 - 반응 온도, 체류시간 - 이 열분해 과정에서 리그닌에 미치는 영향을 살펴보기 위해 수율을 비롯한 다양한 화학적, 구조적 분석을 수행하였다. 열분해 온도가 증가하고, 체류시간이 줄어들수록 바이오오일로부터 회수되는 열분해리그닌의 수율은 증가하였다. 열분해리그닌의 분자량은 백합나무 MWL (milled wood lignin)에 비해 1/10 수준인 약 1,200 mol/g로 측정되었다. 열분해리그닌 내 포함된 작용기 함량과 $^{13}C$ NMR 분석을 통해 바이오매스가 열분해되는 동안 탈메톡실화 반응과 리그닌의 propane side chain 분해반응이 우세하게 일어난다는 사실을 확인하였다.