• Biotechnology and Bioprocess Engineering:BBE
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• 제10권3호
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• pp.225-229
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• 2005

To investigate impediments to plasmid transformation in Brevibacterium flavum BF4 and B. lactofermentum BL1, cell surface barriers were determined by measuring growth inhibition whilst enzymatic barriers were determined by comparing DNA methylation properties. B. lactofermentum was more sensitive to growth inhibition by glycine than B. flavum. Release of cellular proteins during sonication was more rapid for B. lactofermentum than for B. flavum. Plasmid DNA (pCSL 17) isolated from B. flavum transformed recipient $McrBC^+$ strains of Escherichia coli with lower efficiency than $McrBC^-$. McrBC digestion of this DNA confirmed that B. flavum contain methylated cytidines in the target sequence of McrBc sequences but B. lactofermentum contained a different methylation pattern. DNA derived from the B. lactofermentum transformed recipient $EcoKR^+$ strains of E. coli with lower efficiency than $EcoKR^-$, indicating the presence of methylated adenosines in the target sequence of EcoK sequences. The present data describe the differences in the physical and enzymatic barriers between two species of corynebacteria and also provide some insight into the successful foreign gene expression in corynebacteria.

• BMB Reports
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• 제30권6호
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• pp.438-442
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• 1997

${\gamma}-Glutamylamine$ cyclotransferase was purified to homogeneity from soybean (Glycine max) seeds. To our knowledge, it is the first purification of the enzyme from plant origins. The molecular weight of the enzyme estimated by Sephacryl S-300 gel filtration and SDS-PAGE was 27,000, indicating that the enzyme is a monomer. The optimal pH for activity was 8.6. The Km value for ${\gamma}-glutamyldansylcadaverine$ was 11 ${\mu}M$. The enzymatic activity was substantially inhibited by the addition of p-chloromercuribenzoate and partially inhibited by the $Cu^{2+}$ ion. However, neither other modification reagents nor other divalent metal ions affected the enzymatic activity. The comparison between the enzymatic activities of seed extracts treated with cycloheximide and control extracts, and the detection of the same single protein band by western blot analysis at the dormant stage without inhibition with distilled water indicate that ${\gamma}-Glutamylamine$ cyclotransferase is already present at the dormant stage and gradually activated during germination in soybean seeds.

• Korean Chemical Engineering Research
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• 제62권2호
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• pp.147-152
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• 2024

의료용 센서들은 대부분 일회용 제품으로, 검사·진단 비용을 줄이기 위해서는 저가의 전극 소재 개발이 무엇보다 중요하다. 본 연구에서는 일회용 전기화학센서의 전극 소재로 pencil graphite를 도입하여 전처리 효과와 전도성 고분자 폴리아닐린(polyaniline; PANI) 및 금속 산화물 CuO NPs를 이용한 표면 개질(modification)을 통한 전기화학적 특성을 조사하고, 이를 글루코스 검출용 비효소 전기화학센서에 적용하였다. Pencil graphite electrode (PGE)의 표면 활성화를 위한 전처리는 화학적과 전기화학적으로 각각 진행되었으며, 전처리된 샘플들은 시간대전류법(CA)과 순환전압 전류법(CV), 전기화학 임피던스(EIS) 분석법을 이용한 전기화학적 특성 조사를 통해 최종적으로 전기화학적 전처리 방법을 채택하여 CuO NPs/PANI/E-PGE를 제작하였다. 이를 적용한 비효소적 글루코스 검출용 전기화학 센서는 0.282 ~2.112 mM과 3.75423~50 mM의 선형 구간에서 각각 239.18 mA/mM×cm²과 36.99 mA/mM×cm² 정도의 감도(sensitivity)와 17.6 μM의 검출 한계(detection limit), 글루코스에 대한 좋은 선택도(selectivity)를 보였다. 본 연구의 결과를 토대로 PGEs를 활용한 다양한 일회용 센서 응용과 저가의 고성능 전극 소재 개발 가능성을 확인하고, 더 많은 분야에 활용할 수 있을 것으로 기대된다.

• Journal of Microbiology and Biotechnology
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• 제26권5호
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• pp.837-845
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• 2016

A novel endodextranase isolated from Paenibacillus sp. was found to produce isomaltotetraose and small amounts of cycloisomaltooligosaccharides with a degree of polymerization of 7-14 from dextran. To determine the active site, the enzyme was modified with 1-ethyl-3-[3-(dimethylamino)-propyl]-carbodiimide (EDC) and α-epoxyalkyl α-glucosides (EAGs), an affinity labeling reagent. The inactivation followed pseudo first-order kinetics. Kinetic analysis and chemical modification using EDC and EAGs indicated that carboxyl groups are essential for the enzymatic activity. Three Asp and one Glu residues were identified as candidate catalytic amino acids, since these residues are completely conserved across the GH family of 66 enzymes. Replacement of Asp189, Asp340, or Glu412 completely abolished the enzyme activity, indicating that these residues are essential for catalytic activity.

• BMB Reports
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• 제48권8호
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• pp.431-437
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• 2015

Notch signaling plays a pivotal role in cell fate determination, cellular development, cellular self-renewal, tumor progression, and has been linked to developmental disorders and carcinogenesis. Notch1 is activated through interactions with the ligands of neighboring cells, and acts as a transcriptional activator in the nucleus. The Notch1 intracellular domain (Notch1-IC) regulates the expression of target genes related to tumor development and progression. The Notch1 protein undergoes modification after translation by posttranslational modification enzymes. Phosphorylation modification is critical for enzymatic activation, complex formation, degradation, and subcellular localization. According to the nuclear cycle, Notch1-IC is degraded by E3 ligase, FBW7 in the nucleus via phosphorylation-dependent degradation. Here, we summarize the Notch signaling pathway, and resolve to understand the role of phosphorylation in the regulation of Notch signaling as well as to understand its relation to cancer. [BMB Reports 2015; 48(8): 431-437]

• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.118-123
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• 2001

The alginate lyase A1-III gene of Sphingomonas species A1 is composed of 1,077 nucleotides, encoding a protein (359 amino acids) with a molecular mass of 40,322 Da. Recombinant A1-III expressed in Escherichia coli exhibited the same full enzymatic activity as native A1-III. In order to identify the critical residue for activity, a site-directed mutation was introduced into the A1-III gene (H192A, His192->Ala). Recombinant A1-III (H192A) exhibited a significant decrease in enzyme activity (one-thirty thousandth of that of A1-III), without any conformational change, as detected by the CD spectra in the far UV region. Also, the chemical modification of wild-type A1-III with methyl 4-nitro benzene sulfonate resulted in a 40% decrease from the initial activity, whereas the same modification of A1-III (H192A) produced no change in the activity. The role of His192 on the catalytic process was also explored based on a model of A1-III docked with mannuronic acid into the active site.

• 한국분말재료학회지
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• 제14권4호
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• pp.256-260
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• 2007

The surface of magnetite ($Fe_{3}O_{4}$) nanoparticles prepared by coprecipitation method was modified by carboxylic acid group of poly(3-thiophenacetic acid (3TA)) and meso-2,3-dimercaptosuccinic acid (DMSA). Then the lysozyme protein was immobilized on the carboxylic acid group of the modification of the magnetite nanoparticles. The magnetite nanoparticles are spherical and the particle size is approximately 10 nm. We measured quantitative dispersion state by dispersion stability analyzer for each $Fe_{3}O_{4}$ nanoparticles with and without surface modification. The concentration of lysozyme on the modified magnetite nanoparticles was also investigated by a UV-Vis spectrometer and compared to that of magnetite nanoparticles without surface modification. The functionalized magnetite particles had higher enzymatic capacity and dispersion stability than non-functionalized magnetite nanoparticles.

• 한국식품과학회지
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• 제19권3호
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• pp.212-219
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• 1987

재래종 적색 자두 (Prunus salicina)에서 효소를 추출하여 4종류의 polyphenol화합물과 반응시켜 얻어진 갈변반응 생성물에 대하여 Bacillus subtilis H17과 M45를 이용한 rec-assay와 Salmonella typhimurium TA98과 TA100 두 균주를 이용한 Ames test, 그리고 calfcthymus DNA를 이용하는 DNA절단시험을 이용하여 돌연변이원성과 돌연변이 억제작용을 조사하였다. 포자 rec-assay 에서는 pyrogallol, hydroxyhydroquinone, 3,4-dihydroxytoluene, chlorogenic acid 의 갈변반응 생성물은 모두 DNA손상능력이 없었으며 8가지 금속이온 중 ${Zn}^{2+}$과 ${Ni}^{2+}$의 첨가로 고초균 DNA손상에 약한 영향을 나타내었다. DNA절단시험 결과 4종류 갈변반응 생성물 모두 DNA절단작용이 없었으며 금속이온의 영향에 있어서는 pyrogallol 갈변반응 생성물이 ${Cu}^{2+}$의 영향을 받아 ${Cu}^{2+}$의 농도가 증가함에 따라 강한 절단작용을 나타내었으며 3,4-dihydroxytoluene 과 hydroxyhydroquinone갈변반응 생성물은 금속이온의 영향을 전혀 받지 않았다. 또한 chlorogenic acid갈변반응 생성물은 DNA 절단을 억제하는 효과를 나타내었다. Ames test에서는 4가지 갈변반응 생성물 모두 변이원성은 없었으며 benzo$[{\alpha}]$pyrene을 사용한 변이원성 억제작용 실험결과 benzo$[{\alpha}]$pyrene의 활성을 강하게 억제하는 것으로 나타났다.

• 한국식품영양과학회지
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• 제42권2호
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• pp.262-267
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• 2013

본 연구는 당근(Daucus carota var. sativa) 가공방법 중 현재 주로 사용되고 있는 기계적 마쇄 공정으로 인하여 파괴되는 영양소의 손실을 최소화하기 위하여 식물 세포벽에 존재하는 불용성 물질인 protopectin을 가수분해하여 수용성 물질인 pectin으로 전환시키는 효소인 protopectinase를 이용하여 세포의 막을 보존하고 세포 안에 존재하는 영양소의 손실의 차이를 알아보고자 하였다. 당근의 회수율을 측정한 결과 효소처리군과 마쇄 공정 처리군을 비교하였을 때 효소처리군의 회수율은 81%, 잔사율은 19%을 보인 반면, 마쇄처리군은 회수율 56%, 잔사율 44%를 보여 약 20% 정도의 회수율 차이를 보였다. 이는 가공 후 수율 및 폐기량에서 많은 차이를 보일 것으로 판단된다. 당근의 효소 처리군과 마쇄 처리군의 성분 변화를 비교하기 위하여 당근의 주요성분인 ${\beta}$-carotene의 함량 변화를 측정한 결과 protection factor(PF) 각각 $2.2{\pm}0.2$ PF, $1.4{\pm}0.4$ PF의 차이를 보였으며, 총 폴리페놀 함량은 $89{\pm}3.42{\mu}g/g$, $64{\pm}4.16{\mu}g/g$, 총 플라보노이드 함량은 각각 $68{\pm}2.73\mu}g/g$, $41{\pm}3.26{\mu}g/g$을 보임으로써 세포막의 보존으로 인한 영양소의 파괴가 기계적 마쇄 처리군에 비하여 덜 발생한 것을 확인할 수 있었다. 두 처리군의 항산화력을 측정하기 위하여 DPPH radical 소거능과 hydroxyl radical 소거능, 아질산염 소거능을 측정하였으며 DPPH radical 소거능은 1,000 ppm에서 $87{\pm}0.29%$, $74{\pm}1.56%$로 약 13%의 DPPH radical 소거능을 보였고, hydroxyl radical 소거능 결과 10,000 ppm에서 $44{\pm}0.49%$와 $32{\pm}0.48%$로 약 12%의 hydroxyl radical 소거능을 보였다. 아질산염 소거능 측정 결과 1,000 ppm에서 $59{\pm}0.53%$와 $46{\pm}0.62%$로 약 13% 높은 아질산염 소거능을 보였다. 이는 protopectinase 효소 처리로 인한 세포막의 보존이 가공 중 발생되는 영양소의 손실을 줄임과 동시에 당근이 가지고 있는 항산화 물질들을 보존하고 있음을 확인할 수 있었다.

• 한국식품조리과학회지
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• 제9권4호
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• pp.278-283
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• 1993

This study was attempted to investigate the effects of enzymatic modification of milk protein with protease on functional properties. The selected functional properties were solubility, emulsifying activity (EA), emulsion stability(ES), foam expansion(FE), and foam stability(FS). These properties were measu-red from pH 3.0 to pH 8.0. The proteases used in this study were iaolated from Meju(fermemted soybean) and had specific activity of 250 units/㎎ protein at pH 7.0, 1600 units of pretense was used for 1gr. of skim milk protein. Skim milk showed 30.5％ degree of hydrolysis for 1 hr. and 36.4% degree of hydrolysis for 3.5 hrs. of protease treatment at pH 7.0. Solubility of native skim milk, control, 1 hr. and 3.5 hrs. groups were 3.37, 3.64, 10.21, 14.34％o at pH 4.0 respcetively. The emulsifying activity of native skim milk, control, 1 hr. and 3.5 hrs. groups were 38.8,42.0,43.0,46.7ft at pH 4.0, respectively. Enzymatic modification resulted in the increase of solubility and emulsifying activity at pH 4.0. However at pH 5.0 emulsifying activity of 1 hr. and 3.5 hr. group were lower than native skim milk and control groups. 1 hr. protease treatment was found to be most effective way of increasing foam expansion at pH 4.0 to 6.0. It was supported that, protease treated skim milk can be used to improve solubility, emulsifying activity, foam expansion at acid pH. meju protease. skim milk, solubility, emulsion, foam.