• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.153-157
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• 2004

Tyrosine phenol-lyase (TPL) is a useful enzyme for the synthesis of pharmaceutical aromatic amino acids. In the current study, sequential DNA shuffling and screening were used to enhance the stability of TPL. Twenty-thousand mutants were screened, and several improved variants were isolated. One variant named A13V, in which the $13^{th}$ amino acid alanine was substituted by valine, exhibited a higher temperature and denaturant stability than the wild-type TPL. The purified mutant TPL, A13V, retained about 60% of its activity at $76^\circ{C}$, whereas the activity of the wild-type TPL decreased to less than 20% at the same temperature. Plus, A13V exhibited about 50% activity with 3 M urea, while the wild-type TPL lost almost all its catalytic activity, indicating an increased denaturant tolerance in the mutant A13V. It is speculated that the substitution of Val for the Ala in the $\beta$-strand of the N-terminal arm was responsible for the heightened stabilization, and that the current results will contribute to further research on the structural stability of TPL.

• 한국염색가공학회지
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• 제27권4호
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• pp.261-269
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• 2015

Two new D-${\pi}$-A dyes were synthesized by the condensation reaction between active methyl and aromatic aldehyde and its biothiol sensing properties in DMSO/water were investigated by UV-vis spectroscopy. Upon addition of $Hg^{2+}$, the solution of D-${\pi}$-A dyes showed color change and the absorption band shows a formation of a dye-$Hg^{2+}$ coordination complex. These dyes exhibited high selectivity for $Hg^{2+}$ as compared with other cations. The dye-$Hg^{2+}$ could be recovered by adding glutathion(GSH). The absorption intensity of dye-$Hg^{2+}$ increased only by the addition of glutathione(GSH). The competition experiments revealed that no obvious interference was observed by performing the titration with the mixture of glutathione(GSH) and other amino acids. The results indicated that these D-${\pi}$-A dyes were highly selective for glutathione(GSH) detection.

• Journal of Microbiology and Biotechnology
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• 제23권2호
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• pp.218-224
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• 2013

The aldo-keto reductases catalyze reduction reactions using various aliphatic and aromatic aldehydes/ketones. Most reductases require NADPH exclusively as their cofactors. However, NADPH is much more expensive and unstable than NADH. In this study, we attempted to change the five amino acid residues that interact with the 2'-phosphate group of the adenosine ribose of NADPH. These residues were selected based on a docking model of the YOL151W reductase and were substituted with other amino acids to develop NADH-utilizing enzymes. Ten mutants were constructed by site-directed mutagenesis and expressed in Escherichia coli. Among them, four mutants showed higher reductase activities than wild-type when using the NADH cofactor. Analysis of the kinetic parameters for the wild type and mutants indicated that the $k_{cat}/K_{m}$ value of the Asn9Glu mutant toward NADH increased 3-fold. A docking model was used to show that the carboxyl group of Glu 9 of the mutant formed an additional hydrogen bond with the 2'-hydroxyl group of adenosine ribose. The Asn9Glu mutant was able to produce (R)-ethyl-4-chloro-3-hydroxyl butanoate rapidly when using the NADH regeneration system.

• Advances in nano research
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• 제14권4호
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• pp.355-362
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• 2023

Physical exercise, especially intense exercise and high intensity interval training (HIIT) by trampoline, can lead to muscle injuries. These effects can be reduced with intelligent products made of nanocomposite materials. Most of these nanocomposites are polymers reinforced with silicon dioxide, alumina, and titanium dioxide nanoparticles. This study presents a polymer nanocomposite reinforced with silica. As a result of the rapid reaction between tetraethyl orthosilicate and ammonia in the presence of citric acid and other agents, silica nanostructures were synthesized. By substituting bis (4-amino phenoxy) phenyl-triptycene in N, N-dimethylformamide with potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C, the diamine monomer bis (4-amino phenoxy) phenyl-triptycene is prepared. We synthesized a new polyaromatic (imide) with triptycene unit by sol-gel method from aromatic diamines and dianhydride using pyridine as a condensation reagent in NMP. PI readily dissolves in solvents and forms robust and tough polymer films in situ. The FTIR and NMR techniques were used to determine the effects of SiO₂ on the sol-gel process and the structure of the synthesized nanocomposites. By using a simultaneous thermal analysis (DTA-TG) method, the appropriate thermal operation temperature was also determined. Through SEM analysis, the structure, shape, size, and specific surface area of pores were determined. Analysis of XRD results is used to determine how SiO₂ affects the crystallization of phases and the activation energy of crystallization.

• 한국자원식물학회지
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• 제9권3호
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• pp.230-238
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• 1996

재배장소(栽培場所)에 따른 야생(野生)더덕 및 재배(栽培)더덕의 기상환경(氣象環境), 생육특성(生育特性), 일반성분(一般成分), 유리(遊離) 아미노산(酸) 및 식물성(植物性) 정유성분(精油成分)을 비교분석(比較分析)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 자생지(自生地)는 재배지(栽培地에)에 비하여 기온(氣溫)이 $2{\sim}3^{\circ}C$ 지온(地溫)은 $2^{\circ}C$ 정도(程度)로 낮았고 조도(照度) 량(量낮)은 재배지(栽培地)의 2.9%였다. 자생지(自生地) 토양(土壤)의 pH는 재배지(栽培地)보다 다소 낮았으며 유기물(有機物) 함량(含量)은 4.8%로 1.7배(倍) 정도 높게 나타났다. 2. 자생지(自生地) 재배(栽培)더덕의 개화기(開花期)가 8월(月)3일(日)로 같았지만 재배지(栽培地) 야생(野生)더덕은 재배(栽培) 더덕 보다 10일(日) 늦은 8월(月)15일(日)이었다. 만장(蔓長), 엽장(葉長), 경경(莖徑) 등(等)은 재배(栽培) 장소(場所)와는 무관(無關)하게 야생(野生)더덕에서 저조(低調)하였으나 방향성(芳香性)은 평균(平均) 5로서 재배(栽培)더덕이 평균(平均) 3.5인 것에 비해 높은 것으로 나타났다. 3. 야생(野生)더덕의 생체중(生體重)은 평균(平均) 11g/주(株)인 것에 비하여 재배(栽培)더덕은 23.5g/주(株딘)였으나 방향성(芳香性)은 재배지(栽培地)에서는 차이(差異)가 없었으나 자생지(自生地)에서는 야생(野生)더덕이 5 정도(程度)로 다소 높은 경향(傾向)을 보였다. 4. 야생(野生)더덕과 재배(栽培)더덕의 재배장소별(栽培場所別) 일반성분(一般性分)의 조성(組成)은 조단백질(粗蛋白質)의 경우(境遇) 재배장소(栽培場所)에 따른 차이(差異)를 보였으며 자생지(自生地)보다 재배지(栽培地)에서 높은 함량(含量)을 보였고 조(粗)사포닌은 재배지(栽培地)보다 자생지(自生地)에서 높은 함량(含量)을 보였다. 5. 무기성분함양(無機成分含量)의 차이(差異)는 K의 경우(境遇) 자생지(自生地)에서 보다 재배지(栽培地)에서 평균적(平均的)으로 10배이상(倍以上) 정도(程度) 높은 함량(含量)의 차이(差異)를 보였으나 Mn, Zn, Na, Cu 등(等)은 일정(一定)한 경향(傾向)을 보이지 않는 것으로 나타났다. 6. 유리(遊離) 아미노산(酸)의 함량(含量)은 자생지(自生地은)보다 재배지(栽培地)에서 전반적(全般的)으로 높은 함량(含量)을 나타내었고, 특(特)히 Arginine은 다른 성분(成分)들과 비교(比較)해 볼 때 가장 높은 조성(組成)의 차이(差異)를 나타내었다. 7. 야생(野生)더덕과 재배(栽培)더덕의 정유성분수율(精油成分收率)은 자생지재배(自生地栽培)에서는 모두 0.004% 였고 재배지(栽培地)에서는 야생(野生)더덕이 0.005%였다. 8. 더덕의 재배장소(栽培場所)에 따른 향기성분(香氣成分)은 총(總) 21종(種)이었으며 自生地(自生地)에서 야생(野生)더덕은 16종(種), 재배(栽培)더덕은 18종(種)이었고, 재배지(栽培地)에서 야생(野生) 더덕은 14종(種), 재배(栽培)더덕은 20(種)이었다. 9. Trans-2-hexanol은 야생(野生)더덕의 자생지(自生地) 재배(栽培)에서 피이크 면적(面積) 당(當) 50.3%, 재배지(栽培地)에서 피이크 면적(面積) 당(當) 43.3%를 보였으며 amylalcohol, furfuryl acetate, 2-methoxy-4-vinyl phenol(MVP)는 재배(栽培)더덕에서만 확인(確認)되었다.

• KSBB Journal
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• 제24권1호
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• pp.75-79
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• 2009

Coenzyme $Q_{10}$ 고역가 변이주인 Agrobacterium tumefaciens KPU-11-03의 다양한 유기 질소원에 대한 coenzyme $Q_{10}$ 생산량과 coenzyme $Q_{10}$의 구성비율 등을 비교한 결과, CSP 첨가 시 coenzyme $Q_{10}$ 생산량은 212.7 mg/l, 구성비율은 94%로 다른 유기질소원에 비해 매우 높게 나타났다. 특히 Bacto tryptone, Bacto peptone, soybean meal, casamino acid 등의 유기 질소원 첨가 시에는 극히 낮은 coenzyme $Q_{10}$ 역가를 나타내어 균체내의 coenzyme $Q_{10}$의 축적은 유기 질소원의 종류 즉 아미노산의 종류 및 량과 상관성이 있음을 추정할 수 있었다. 또한 무기질소원에 대하여 실험한 결과, $(NH_4)_2SO_4$ 첨가 시에 coenzyme $Q_{10}$역가가 약 2배 증가하였고 다른 무기질소원에 사용 시에는 오히려 감소하였다. Coenzyme $Q_{10}$ 역가와 관련된 아미노산을 확인하기 위해 유기질소원으로 Bacto tryptone을 첨가한 배지에 9가지의 아미노산을 첨가하여 실혐한 결과, 방향족 아미노산인 tyrosine 첨가 시의 coenzyme $Q_{10}$ 생산량은 99.5 mg/l로 비첨가구보다 약 8.2배 증가하였으나 phenylalanine과 tryptophan등의 다른 방향족 아미노산의 첨가 시에는 coenzyme $Q_{10}$ 생산량이 오히려 감소하는 것으로 나타나 tyrosine의 첨가가 coenzyme $Q_{10}$ 역가에 매우 중요함을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제25권10호
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• pp.1709-1713
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• 2015

Sepiapterin is a precursor for the synthesis of tetrahydrobiopterin (BH4), which is a wellknown cofactor for aromatic amino acid hydroxylation and nitric oxide synthesis in higher mammals. In this study, a recombinant Escherichia coli BL21(DE3) strain harboring cyanobacterial guanosine 5’-triphosphate cyclohydrolase 1 (GCH1) and human 6-pyruvoyltetrahydropterin synthase (PTPS) genes was constructed to produce sepiapterin. The optimum conditions for T₇ promoter–driven expression of GCH1 and PTPS were 30℃ and 0.1 mM isopropyl-β-D-thioglucopyranoside (IPTG). The maximum sepiapterin concentration of 88.1 ± 2.4 mg/l was obtained in a batch cultivation of the recombinant E. coli, corresponding to an 18-fold increase in sepiapterin production compared with the control condition (37℃ and 1 mM IPTG).

• BMB Reports
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• 제43권9호
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• pp.584-592
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• 2010

Tetrahydrobiopterin (BH4) is a multifunctional cofactor of aromatic amino acid hydroxylases and nitric oxide synthase (NOS) as well as an intracellular antioxidant in animals. Through regulation of NOS activity BH4 plays a pivotal role not only in a variety of normal cellular functions but also in the pathogenesis of cardiovascular and neurodegenerative diseases, which develop under oxidative stress conditions. It appears that a balanced interplay between BH4 and NOS is crucial for cellular fate. If cellular BH4 homeostasis maintained by BH4 synthesis and regeneration fails to cope with increased oxidative stress, NOS is uncoupled to generate superoxide rather than NO and, in turn, exacerbates impaired BH4 homeostasis, thereby leading to cell death. The fundamental biochemical events involved in the BH4-NOS interplay are essentially the same, as revealed in mammalian endothelial, cardiac, and neuronal cells. This review summarizes information on the cellular BH4 homeostasis in mammals, focusing on its regulation under normal and oxidative stress conditions.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2001년도 Proceedings of 2001 International Symposium
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• pp.118-119
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• 2001

A Southern-hybridization analysis and size-selected DNA library screening led to the isolation of a 6.3-kbp S. setonii DNA fragment, from which the Cl20-encoding genetic locus was found to be located within a 1.4-kbp DNA fragment. A complete nucleotide sequencing analysis of the 1.4-kbp DNA fragment revealed a 0.84-kbp ORF, which showed a strong overall amino acid similarity to the known high－G＋C gram-positive bacterial mesophilic C120s. The heterologous expression of the cloned 1.4-kbp DNA fragment in E. coli demonstrated that this Cl20 possessed a thermophilic activity within a broad temperature range and showed a higher activity against 3-methy1catechol than catechol or 4-methy-catechol, but no activity against protocatecuate.

• Archives of Pharmacal Research
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• 제13권2호
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• pp.142-146
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• 1990

Reaction of ethyl 4-chloro-2-phenylpyrimidine-4-carboxylate (4) with 5-chloro-2-methylthiophenol or 3-aryl-4-phenyl-1, 2, 4-triazole-5 thiol yielded the corresponding thioethers (5) and (8a, b), respectively. Careful alkaline hydrolysis of (5) yielded the corresponding carboxylic acid (6). Reaction of (4) with p-aminoacetophenone yielded compound (10) which was reacted with certain aromatic aldehyde to afford the$\alpha,\beta$-unsaturated ketones (11a-d). Condensation of (11a-d) with malononitrile or phenylhydrazine yielded the 2-amino-3-cyanopyridines (12a-f) or the 2-pyrazolines (13a, b) respectively. Seven representative compounds were tested for their in vitro antimicrobial activity against some pathogenic micro-organisms, some of them were proved to be active.