• Journal of Microbiology and Biotechnology
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• 제33권1호
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• pp.28-34
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• 2023

Endoribonuclease YbeY is specific to the single-stranded RNA of ribosomal RNAs and small RNAs. This enzyme is essential for the maturation and quality control of ribosomal RNA in a wide range of bacteria and for virulence in some pathogenic bacteria. In this study, we determined the crystal structure of YbeY from Staphylococcus aureus at a resolution of 1.9 Å in the presence of zinc chloride. The structure showed a zinc ion at the active site and two molecules of tricarboxylic acid citrate, which were also derived from the crystallization conditions. Our structure showed the zinc ionbound local environment at the molecular level for the first time. Molecular comparisons were performed between the carboxylic moieties of citrate and the phosphate moiety of the RNA backbone, and a model of YbeY in complex with a single strand of RNA was subsequently constructed. Our findings provide molecular insights into how the YbeY enzyme recognizes singlestranded RNA in bacteria.

• 한국환경과학회지
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• 제32권11호
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• pp.757-765
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• 2023

Lead, a heavy metal widely employed in various industries, continues to pose a threat to both human health and the environment. Therefore, the development of a sensor capable of rapidly and accurately detecting lead(II) ions in real-time at contaminated sites is crucial. In this study, we have engineered a fluorescent sensor with the ability to efficiently detect lead(II) ions under actual environmental conditions, including tap water and freshwater. The compound, tetraphenylethylene carboxylic acid derivative (TPE-COOH), exhibits high selectivity and sensitivity toward lead(II) ions in aqueous solution, where the interaction between TPE-COOH and lead(II) ions leads to its aggregation, thus triggering a fluorescence "turn-on" based on the aggregation-induced emission (AIE) mechanism. Impressively, compound TPE-COOH proficiently detects lead(II) ions within a range of 30 to 100 𝜇M in tap water and freshwater, even in the presence of various interfering substances.

• 농업과학연구
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• 제50권4호
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• pp.759-771
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• 2023

Plant growth-promoting rhizobacteria (PGPR) are naturally occurring bacteria that intensively colonize plant roots and are crucial in promoting the crop growth. These beneficial microorganisms have garnered considerable attention as potential bio-inoculants for sustainable agriculture. PGPR directly interacts with plants by providing essential nutrients through nitrogen fixation and phosphate solubilization and accelerating the accessibility of other trace elements such as Cu, Zn, and Fe. Additionally, they produce plant growth-promoting phytohormones, such as indole acetic acids (IAA), indole butyric acids (IBA), gibberellins, and cytokinins.PGPR interacts with plants indirectly by protecting them from diseases and infections by producing antibiotics, siderophores, hydrogen cyanide, and fungal cell wall-degrading enzymes such as glucanases, chitinases, and proteases. Furthermore, PGPR protects plants against abiotic stresses such as drought and salinity by producing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and modulating plant stress markers. Bacteria belonging to genera such as Bacillus, Pseudomonas, Burkholderia, Pantoa, and Enterobacter exhibit multiple plant growth-promoting traits, that can enhance plant growth directly, indirectly, or through synergetic effects. This comprehensive review emphasizes how PGPR influences plant growth promotion and presents promising prospects for its application in sustainable agriculture.

• 분석과학
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• 제37권4호
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• pp.239-250
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• 2024

This study reports the synthesis of a bi-dentate Schiff base ligand (L), 7-(2-((2-formylbenzylidene) amino)-2-phenylacetamido)-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, prepared from phthalaldehyde and cephalexin antibiotic. The synthesized Schiff base ligand (L) and the secondary ligand alizarin (Az) are used to prepare the new complexes [M(Az)₂(L)] and [Cr(Az)₂(L)]Cl, where M = Mn(II), Co(II), Ni(II), Cu(II), and Zn(II). The mode of bonding of the Schiff base has been characterized by UV-Visible, FT-IR, Mass, ¹H-, and ¹³C-NMR spectroscopic techniques, and micro elemental analysis (CHNS). The complexes were characterized using UV-Vis, FT-IR, molar conductance, magnetic moment, and thermal analysis (TG/DTG). The molar conductance data revealed that the complexes are non-electrolytes except for [Cr(L)(Az)₂]Cl, which is an electrolytic type 1:1. The Schiff base and its complexes have been tested for their biological activity against two strains of bacteria and one fungus. When screened against gram-positive and gram-negative pathogens, the Az and L ligands and their complexes showed potential antimicrobial activity.

• 공업화학
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• 제17권2호
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• pp.132-137
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• 2006

Methyl methacrylate (MMA), 2-hydroxy ethylmethacrylate (2-HEMA), n-butyl acrylate (n-BA) acrylic acid (AAc)를 아크릴레이트 단량체로 사용하고 친수성기인 카르복실 말단기를 갖는 수분산성 폴리우레탄을 시드로 하여 시드중합 방법을 이용한 폴리우레탄 아크릴레이트 하이브리드 에멀젼을 합성하였다. 합성된 혼성 에멀젼의 입자경과 폴리우레탄 수분산체의 입자경과 단독 아크릴레이트 에멀젼의 입자경 그리고 수분산 폴리우레탄과 아크릴레이트 에멀젼을 기계적으로 브랜드한 혼합물의 입자경을 입도 분석기를 이용하여 입자의 크기 및 분포를 측정하였고 하이브리드한 에멀젼은 기계적으로 브랜드한 에멀젼보다 평균입자경이 큰 것을 알 수 있었다 그리고 수분기 용매에 대한 팽윤을 비교 분석하였다. 또한 물리 화학적 물성을 개선하기 위하여 폴리우레탄 아크릴레이트 하이브리드 에멀젼에 멜라민 포름알데히드 경화제의 첨가에 따른 효과를 비교하였다.

• 콘크리트학회지
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• 제7권2호
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• pp.175-182
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• 1995

스티렌과 무수말레인산의 라디칼 공중합에 의해 스티렌-무수말레인산 공중합체(SMA)를 합성하고 SMA를 m-amino phenol과 치환반응하여 m-amino phenol 이 치환된 스티렌-무수말레인산 공중합체(mSMA)도 합성하였다. 합성한 SMA와 mSMA를 황산화하여 각각 황산화 SMA(SSMA) 및 황산화 mSMA(SmSMA)를 제조하였다. 공중합체의 합성은 적외분광스펙트럼의 특성피크로부터 확인할 수 있었다. 원소분석 결과 mSMA의 m-amino phenol의 치환율은 44%이었고 이것은 황산화 과정을 거치면서 35%로 감소하였다. 공중합체의 시멘트에 대한 흡착실험 결과 공중합체의 첨가량이 적을수록 흡착율이 높게 나타났고, 첨가량에 관계없이 SSMA의 흡착율이 SmSMA의 그것보다 크게 나타났다. 본 연구에서 합성한 공중합체 (SSMA, SmSMA)는 시멘트 분산제로서의 가능성이 기대되어진다.

• 한국식품위생안전성학회지
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• 제5권3호
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• pp.159-164
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• 1990

To detect and quantitation residual antibiotics and antibacterial agents in meats, we performed a biological assay employing the three microorganisms Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341, and Bacillus cereus var. mycoides ATCC 11778 for the screening purpose and developed a Gas Chromatography-mass Spectrometry(GC/MS) analysis for the confirmation and quantiation. In the biological assay (paper disk method), three test solution are used depending on the character of the residual antibiotics and antibacterial agents, follow by a simple clean up procedure which includes homogenization with Mcilvaine buffer, defatting with includes homogenization with Mcilvaine buffer, defatting with hexane, extraction with chloroform, clean-up by Sep-Pak $C_{18}$ and Bakerbond SPE carboxylic acid column. The chloroform layer is used for the analysis of sulfa agents. macrolides antibiotics and antibacterial agents, Adsorbed materials in the Sep-Pak $C_{18}$ were also employed for th analysis of penicillins and tetracyclines. Effluents from the Sep-Pak $C_{18}$ were cleaned-up one more by Bakerbond 10 SPE COOH column and employed for the analysis of aminoglycosides. In the instrumental analysis by using the GC/MSD, residual antibiotics and antibacterial agent were quantitated by selected ion monitoring (SIM) mode after derivatization. A simultaneous analysis of six residual antibiotic and antibacterial agent such as oxytetracycline, penicillin, ampicillin, choliraphenicol and thiamphenicol was developed with simple cleanup procedures revealing good recovery and reproducibility. Also, simultaneous detection of macrolides antibiotics such as erythromycin, spiramycin, and oleandomycin was developed after acid hydrolysis due to their large molecular structures. Because of the high reproducibility and selectivity of these two methods, it is very desirable that the combination of the two methods be used in the bioassay for the screening of residual antibiotics and antibacterial agent and that GC/MSD analysis be used for the confirmation and quantitation.

• 동의생리병리학회지
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• 제27권5호
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• pp.631-636
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• 2013

This study was to evaluate the antioxidant properties of the leaf extracts of Diospyros lotus (DLE) on the chemical-induced free radical and rat red blood cell (RBC) oxidative damage in vitro. DLE were prepared by extracting with water. DLE showed the high antioxidant activities on the scavenging of 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid)-induced radicals. An antioxidant activities of DLE was similar to the reference antioxidant butylated hydroxytoluene (BHT) and (${\pm}$)6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox). Reducing power of $1,000{\mu}g/mL$ DLE also was similar to the vitamin C. In RBC, oxidative hemolysis induced by the aqueous peroxyl radical generator (2,2'-Azobis (2-methylpropionamidine) dihydrochloride (AAPH)) were significantly suppressed by DLE in a dose-dependent manner. Furthermore, DLE prevented the depletion of cytosolic antioxidant glutathione in RBC damaged with AAPH. These results suggest that DLE may has value as natural product with its high quality antioxidant properties against oxidative stress.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.157-167
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• 2000

A thermostable chitosanase gene from the isolated strain, Bacillus sp. CK4, was cloned, and its complete DNA sequence was determined. The thermostable chitosanase gene was composed of an 822-bp open reading frame which encodes a protein of 242 amino acids and a signal peptide corresponding to a 30 kDa enzyme in size. The deduced amino acid sequence of the chitosanase from Bacillus sp. CK4 exhibits 76.6%, 15.3%, and 14.2% similarities to those from Bacillus subtilis, Bacillus ehemensis, and Bacillus circulans, respectively. C-terminal homology analysis shows that Bacillus sp. CK4 belongs to the Cluster III group with Bacillus subtilis. The size of the gene was similar to that of a mesophile, Bacillus subtilis showing a higher preference for codons ending in G or C. The functional importance of a conserved region in a novel chitosanase from Bacillus sp. CK4 was investigated. Each of the three carboxylic amino acid residues were changed to E50D/Q, E62D/Q, and D66N/E by site-directed mutagenesis. The D66N/E mutants enzymes had remarkably decreased kinetic parameters such as $V_{max}$ and k$\sub$cat/, indicating that the Asp-66 residue was essential for catalysis. The thermostable chitosanase contains three cysteine residues at position 49, 72, and 211. Titration of the Cys residues with DTNB showed that none of them were involved in disulfide bond. The C49S and C72S mutant enzymes were as stable to thermal inactivation and denaturating agents as the wild-type enzyme. However the half-life of the C211S mutant enzyme was less than 60 min at 80$^{\circ}C$, while that of the wild type enzyme was about 90 min. Moreover, the residual activity of C211S was substantially decreased by 8 M urea, and fully lost catalytic activity by 40% ethanol. These results show that the substitution of Cys with Ser at position 211 seems to affect the conformational stability of the chitosanase.

• 콘크리트학회지
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• 제8권4호
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• pp.161-169
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• 1996

화학조성이 다른 스티렌-무수말레인산 공중합체(1:1SMA, 5:1SMA)를 합성하고 이들을 황산화하여 수용성의 공중합체(1:1SSMA, 5:1SSMA)를 제조하였다. 이들 공중합체를 첨가한 시멘트 모르타르의 유동특성을 조사한 결과, 5:1SSMA는 1:1SSMA보다 우수한 플로우를 나타내었다. 또한 5:1SSMA를 1%첨가한 시멘트 모르타르는 60분 후에도 95% 이상의 플로우를 유지하였다. 한편 합성고분자를 0.5% 첨가한 경화시멘트 모르타르의 압축강도도 조사하였다. 그 결과 5:1SSMA를 첨가한 시험체의 28일 압축강도는 첨가하지 않은 시험체보다 41%증가한 반면 1:1SSMA는 29%의 증가를 나타내었다. 본 연구에서 제조한 5:1SSMA는 새로운 카르본산계 고성능감수제로서 그 활용이 크게 기대되어 진다.