• BMB Reports
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• 제49권5호
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• pp.245-246
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• 2016

The level and activity of critical regulatory proteins in cells are tightly controlled by several tiers of post-translational modifications. HIF-1α is maintained at low levels under normoxia conditions by the collaboration between PHD proteins and the VHL-containing E3 ubiquitin ligase complex. We recently identified a new physiologically relevant mechanism that regulates HIF-1α stability in the nucleus in response to cellular oxygen levels. This mechanism is based on the collaboration between the SET7/9 methyltransferase and the LSD1 demethylase. SET7/9 adds a methyl group to HIF-1α, which triggers degradation of the protein by the ubiquitin-proteasome system, whereas LSD1 removes the methyl group, leading to stabilization of HIF-1α under hypoxia conditions. In cells from knock-in mice with a mutation preventing HIF-1α methylation (Hif1α^KA/KA), HIF-1α levels were increased in both normoxic and hypoxic conditions. Hif1α^KA/KA knock-in mice displayed increased hematological parameters, such as red blood cell count and hemoglobin concentration. They also displayed pathological phenotypes; retinal and tumor-associated angiogenesis as well as tumor growth were increased in Hif1α^KA/KA knock-in mice. Certain human cancer cells exhibit mutations that cause defects in HIF-1α methylation. In summary, this newly identified methylation-based regulation of HIF-1α stability constitutes another layer of regulation that is independent of previously identified mechanisms.

• Korean Chemical Engineering Research
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• 제44권1호
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• pp.92-96
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• 2006

유기용매에서 효소를 이용하면 다양한 선택적 반응을 쉽게 수행할 수 있어 산업적 적용 가능성이 매우 높지만, 효소의 안정성 저하는 아직까지 큰 문제 중의 하나로 남아있다. 유기용매에서 효소 반응시 효소의 실활 원인과 효소의 안정화 방법 연구를 위하여 단백질의 folding에 관여하는 molecular chaperone의 일종인 heat-shock protein Hsp90을 이용하여, 대표적인 유기용매 반응시스템에서의 과산화효소 HRP 안정성 향상 연구를 수행하였다. 그 결과 Hsp90은 30％ DMSO, 30％ 및 50％ dioxane 완충용액에서 HRP의 실활 방지 효과를 보였고, 실활된 효소의 재생에도 탁월한 효과를 보였다. 그리고 형광분석과 CD(circular dichroism)에 의한 구조분석을 수행하여 Hsp90이 유기용매에 의해 unfolding되어 있는 효소를 다시 refolding하는 데 기여함을 알았다.

• Applied Biological Chemistry
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• 제39권4호
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• pp.282-286
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• 1996

어류껍질 젤라틴의 수식에 의한 유화성 및 유화안정성과 같은 기능성을 개선하여 적색육어류 연제품의 품질개선제로 이용할 목적으로 붕장어껍질 젤라틴의 succinylation을 시도하였다. Succinylation의 정도는 젤라틴에 대하여 첨가하는 succinic anhydride의 비율 0.3까지는 첨가량에 따라 증가하였으나, 그 이상의 농도에서는 거의 변화가 없었다. 유지흡수성, 유화성 및 유화안정성은 무수식 젤라틴이 각각 1.8ml/g, 55% 및 49%이었고, 수식에 의해 개선되어 succinylation 정도가 89.9%일 때 이들의 값이 각각 5.8ml/g, 84% 및 78%이었고, 그 이상의 농도에서는 거의 변화가 없거나 서서히 감소하였다. 또한 용해도의 경우 40%, 보수력의 경우 50%, 거품성 및 거품안정성의 경우 0.4 및 0.3정도 개선되었다. 수식 젤라틴은 무수식 젤라틴에 비하여 아미노산조성의 경우 거의 차이가 없었고, 중금속함량은 오히려 낮았다.

• Applied Biological Chemistry
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• 제39권5호
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• pp.374-378
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• 1996

들깨를 여러 볶음조건에서 처리한 후 착유한 들기름의 저장중 산화안정성 변화를 살펴보았다. 이때 들깨의 볶음온도는 $150,\;170,\;190,\;210^{\circ}C$로 볶음시간은 10, 20, 30분으로 하였다. 전체적으로 들깨의 볶음온도가 높고 볶음 시간이 길어질수록 착유한 들기름의 산화안정성은 높아졌다. 들깨를 볶지 않고 착유한 들기름의 유도기간은 3.9일이었으며 $210^{\circ}C$에서 30분 볶아 착유한 들기름의 유도기간은 55일이었다. 들기름의 DPPH에 대한 전자공여작용은 들깨의 볶음온도가 높고 볶음시간을 길게하여 착유한 들기름일수록 증가하는 경향을 보였다. 들깨를 볶지 않고 착유한 들기름의 전자공여능이 24%로 나타난 반면 $210^{\circ}C$에서 30분 볶아 착유한 들기름은 64%이었다. 그리고 들기름의 fluorescence는 들깨의 볶음온도가 높고 볶음시간을 길게 하여 착유한 들기름일수록 증가하였다.

• Journal of Applied Biological Chemistry
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• 제63권4호
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• pp.407-412
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• 2020

Ulmus parvifolia 잎의 약리학적 지표 성분을 제시하기 위해 간단하고 신뢰할 수 있는 HPLC 분석방법을 개발하였다. 지표 성분들은 NMR 및 UPLC-QTof-MS 분석에 의해 neochlorogenic acid (trans-5-O-caffeoylquinic acid, 5-CQA)과 chlorogenic acid (trans-3-O-caffeoylquinic acid, 3-CQA)로 구조 동정 되었다. HPLC를 이용하여 두개 화합물을 포함한 잎 추출물의 정성/정량 분석 방법을 평가하였다. 잎 30% 에탄올 추출물과 지표 성분의 안정성 테스트는 6개월 동안 평가되었다. 그러나 안정성 조사 기간 동안 추출물과 지표 성분들 각각의 함량에 대한 유의한 변화는 관찰되지 않았다.

• The Plant Pathology Journal
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• 제37권3호
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• pp.215-231
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• 2021

Brown leaf spot disease caused by Nigrospora guilinensis on Phellodendron chinense occurs in a large area in Dayi County, Chengdu City, Sichuan Province, China each year. This outbreak has severely reduced the production of Chinese medicinal plants P. chinense and caused substantial economic losses. The bacterial isolate JKB05 was isolated from the healthy leaves of P. chinense, exhibited antagonistic effects against N. guilinensis and was identified as Bacillus megaterium. The following fermentation medium and conditions improved the inhibitory effect of B. megaterium JKB05 on N. guilinensis: 2% glucose, 0.1% soybean powder, 0.1% KCl, and 0.05% MgSO₄; initial concentration 6 × 10⁶ cfu/ml, and a 42-h optimal fermentation time. A composite of 0.1% nano-SiO₂ JKB05 improved the thermal stability, acid-base stability and ultraviolet resistance by 16%, 12%, and 38.9%, respectively, and nano-SiO₂ was added to the fermentation process. The best formula for the wettable powder was 35% kaolin, 4% polyethylene glycol, 8% Tween, and 2% humic acid. The following quality test results for the wettable powder were obtained: wetting time 87.0 s, suspension rate 80.33%, frequency of microbial contamination 0.08%, pH 7.2, fineness 95.8%, drying loss 1.47%, and storage stability ≥83.5%. A pot experiment revealed that the ability of JKB05 to prevent fungal infections on P. chinense increased considerably and achieved levels of control as high as 94%. The use of nanomaterials significantly improved the ability of biocontrol bacteria to control this disease.

• 한국생물정보학회:학술대회논문집
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• 한국생물정보시스템생물학회 2004년도 The 3rd Annual Conference for The Korean Society for Bioinformatics Association of Asian Societies for Bioinformatics 2004 Symposium
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• pp.265-271
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• 2004

The interaction network of protein -protein plays an important role to understand the various biological functions of cells. Currently, the high -throughput experimental techniques (two -dimensional gel electrophoresis, mass spectroscopy, yeast two -hybrid assay) provide us with the vast amount of data for protein-protein interaction at the proteome scale. In order to recognize the role of each protein in their network, the efficient bioinformatical and computational analysis methods are required. We propose a systematic and mathematical method which can analyze the protein -protein interaction network rigorously and enable us to capture the biological and physical essence of a topological character and stability of protein -protein network, and sensitivity of each protein along the biological pathway of their network. We set up a Laplacian matrix of spectral graph theory based on the protein-protein network of yeast proteome, and perform an eigenvalue analysis and apply a perturbation method on a Laplacian matrix, which result in recognizing the center of protein cluster, the identity of hub proteins around it and their relative sensitivities. Identifying the topology of protein -protein network via a Laplacian matrix, we can recognize the important relation between the biological pathway of yeast proteome and the formalism of master equation. The results of our systematic and mathematical analysis agree well with the experimental findings of yeast proteome. The biological function and meaning of each protein cluster can be explained easily. Our rigorous analysis method is robust for understanding various kinds of networks whether they are biological, social, economical...etc

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.96-110
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• 2024

Polymer electrolyte membrane fuel cells (PEMFCs) are green energy conversion devices, for which commercial markets have been established, owing to their application in fuel cell vehicles (FCVs). Development of cathode electrocatalysts, replacing commercial Pt/C, plays a crucial role in factors such as cost reduction, high performance, and durability in FCVs. PtNi octahedral catalysts are promising for oxygen reduction reactions owing to their significantly higher mass activity (10-15 times) than that of Pt/C; however, their application in membrane electrode assemblies (MEAs) is challenged by their low stability. To overcome this durability issue, various approaches, such as third-metal doping, composition control, halide treatment, formation of a Pt layer, annealing treatment, and size control, have been explored and have shown promising improvements in stability in rotating disk electrode (RDE) testing. In this review, we aimed to compare the features of each strategy in terms of enhancing stability by introducing a stability improvement factor for a direct and reasonable comparison. The limitations of each strategy for enhancing stability of PtNi octahedral are also described. This review can serve as a valuable guide for the development of strategies to enhance the durability of octahedral PtNi.

• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1077-1083
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• 2012

Previously, an extracellular ${\alpha}$-amylase (BKA) had been purified from the culture of Bacillus sp. KR8104. Subsequently, the crystal structure of the active enzyme revealed a 422 amino acids polypeptide. In this study, the bka was cloned into E. coli, which encoded a polypeptide of 659 amino acids including two additional fragments: one 44 residues N-terminal fragment and another 193 residues C-terminal fragment. In order to investigate the role of the C-terminal fragment, two constructs with and without this region [$BKA{\Delta}$(N44) and $BKA{\Delta}$(N44C193)] were designed and expressed in E. coli BL21. The optimum pH, thermal stability, and the end-products of starch hydrolysis were found to be similar in both constructs. The $K_m$ and $V_{max}$ values for $BKA{\Delta}$(N44) were lower than $BKA{\Delta}$(N44C193), using either starch or ethylidene-blocked 4-nitrophenylmaltoheptaoside as a substrate.

• Journal of Applied Biological Chemistry
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• 제58권2호
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• pp.157-174
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• 2015

토양 중금속 안정화를 위해 농축수산 부산물, 산업부산물 등과 같은 다양한 폐자원이 활용되고 있다. 일례로 석회, 패각류, 난각류, 산업부산물 등의 알칼리물질, 동물의 뼈 및 인산용액, 인광석 등의 인 함유물질, 퇴비(compost), 가축분(manure), 바이오차(biochar) 등의 유기성물질과 이 외에도 영가철, 제오라이트(zeolite) 등의 다양한 물질들을 토양 내 중금속 안정화의 소재로 활용하기 위한 효율성, 적용성 연구가 진행되고 있다. 이들 물질에 대한 토양 적용 후 중금속 안정화 기작은 일부 보고된 바 있으나 장기적 안정성과 현장 적용성을 평가한 연구는 여전히 부족한 실정이다. 본 연구에서는 여러 가지 폐자원을 활용한 선행 연구들에서 제시된 토양 중금속 안정화 관련 내용을 요약하였다.