• Bulletin of the Korean Chemical Society
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• v.28 no.3
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• pp.365-366
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• 2007

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.220-223
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• 2004

Club root caused by Plasmodiophora brassicae is found in crucifers. Among the over hundreds of Streptomyces isolated from soil in Korea. One strain showed prominent activity against P. brassicae. The strain was identified based on 16S rDNA sequencing and the morphology by a method of scanning electron microscopy. An active compound in the fermented broth obtained from the strain was separated. Even though the complete assignments of the compound remain for future work, the results regarding the isolation and characterization of the strain with a certain activity against P. brassicae are shown in this paper.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.253-255
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• 2005

최근 생물학 문제를 해결하기 위하여 생명 정보 분야에서 많은 컴퓨터 기술들이 응용되고 있다. 플라보노이드 정보는 항암, 항산화 효과가 있는 유용한 물질인 플라보노이드의 연구와 관련된 정보를 분석하고 관리하는 컴퓨터 기술 기반의 응용 기술이다. 현재 플라보노이드 정보 관련 연구는 일부에서 수행되고 있으며 플라보노이드의 다양한 정보를 효율적으로 저장 검색 할 수 있는 시스템은 부족한 실정이다. 플라보노이드 물질에 관한 정보를 더욱 효과적으로 저장 관리하고 관련된 연구자들 간에 정보를 쉽게 공유할 수 있도록 본 논문에서는 플라보노이드 정보를 위한 그리드 웹 포탈 시스템 구조와 관련된 데이타 모델을 제안한다. 본 논문에서 제안한 시스템과 데이타 모델의 유용함을 보이기 위해 웹 기반으로 플라보노이드 정보 그리드 포탈을 구현한다.

• Journal of Microbiology and Biotechnology
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• v.19 no.4
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• pp.387-390
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• 2009

Microbial UDP-glycosyltransferases can convert many small lipophilic compounds into glycons using uridine-diphosphate-activated sugars. The glycosylation of flavonoids affects solubility, stability, and bioavailability. The gene encoding the UDP-glycosyltransferase from Bacillus cereus, BcGT-3, was cloned by PCR and sequenced. BcGT-3 was expressed in Escherichia coli BL21(DE3) with a glutathione S-transferase tag and purified using a glutathione S-transferase affinity column. BcGT-3 was tested for activity on several substrates including genistein, kaempferol, luteolin, naringenin, and quercetin. Flavonols were the best substrates for BcGT-3. The enzyme dominantly glycosylated the 3-hydroxyl group, but the 7-hydroxyl group was glycosylated when the 3-hydroxyl group was not available. The kaempferol reaction products were identified as kaempferol-3-O-glucoside and kaempferol-3,7-O-diglucoside. Kaempferol was the most effective substrate tested. Based on HPLC, LC/MS, and NMR analyses of the reaction products, we conclude that BcGT-3 can be used for the synthesis of kaempferol 3,7-O-diglucose.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1475-1479
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• 2012

Human peroxisome proliferator-activated receptor gamma ($hPPAR{\gamma}$) has been implicated in numerous pathologies, including obesity, diabetes, and cancer. In this study, we verified that amentoflavone is an agonist of $hPPAR{\gamma}$ and probed the molecular basis of its action. It was demonstrated that amentoflavone bound $hPPAR{\gamma}$ with high (picomolar) affinity and increased the binding between $hPPAR{\gamma}$ and steroid receptor coactivator-1 (SRC-1) by approximately 4-fold. Based on a docking study, for the first time, we propose a model of amentoflavone and $hPPAR{\gamma}$ binding in which amentoflavone forms three hydrogen bonds with the side chains of His323, Tyr327, and Arg280 in $hPPAR{\gamma}$ and participates in two hydrophobic interactions.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.465-468
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• 2006

Even though many pesticides are known for barley powdery mildew and wheat leaf rust, alternative controls are necessary, because of consumer rejection of chemical pesticides and the appearance of fungi resistant to fungicides. To discover biopesticides, many broths of microorganisms were screened. Of those, a culture broth of Burkholderia ambifaria showed an excellent antifungal activity against both Erysiphe graminis and Puccinia recondita, which cause barley powdery mildew and wheat leaf rust, respectively.

• Journal of Microbiology and Biotechnology
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• v.19 no.7
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• pp.709-712
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• 2009

Enzymatic glucosylation with glycosyltransferases can be used to regulate the water solubility of aglycone. The drawback of this process is the demand of UDP-glucose as a sugar donor. We made an in-frame fusion of the flavonoid O-glucosyltransferase (OsUGT-3) and sucrose synthase (AtSUS) genes. The resulting fusion protein, OsUGT3-AtSUS, was expressed in E. coli and purified. When sucrose and UDP were supplied, the fusion protein was able to convert quercetin into quercetin O-glucoside without the addition of UDP-glucose. In addition, UDP-glucose was recycled when sucrose was added to the reaction mixture. This fusion protein is useful for the enzymatic production of flavonoid O-glucosides.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2248-2252
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• 2007

SOMT-9 is an O-methyltransferase that utilizes quercetin to produce 3'-methoxy quercetin. In order to determine which amino acids of SOMT-9 are important for this reaction and its regioselectivity, molecular docking experiments followed by site directed mutagenesis were performed. Molecular modeling and molecular docking experiments identified several amino acid residues involved in metal binding, AdoMet binding, and substrate binding. Site-directed mutagenesis showed that Asp188 is critical for metal binding and that Lys165 assists other metal binding residues in maintaining quercetin in the proper position during the reaction. In addition, Tyr207 was shown to play an important role in the determination of the regioselectivity and Met60 was shown to be involved in formation of the hydrophobic pocket necessary for substrate binding. The molecular modeling and docking experiments discussed in this study could be applicable to future research including prediction of substrate binding and regioselectivity of an enzyme.

• Journal of Microbiology and Biotechnology
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• v.20 no.10
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• pp.1393-1396
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• 2010

The attachment of sugar to flavonoids enhances their solubility. Glycosylation is performed primarily by uridine diphosphate-dependent glycosyltransferases (UGTs). The UGT from Bacillus cereus, BcGT-1, transferred three glucose molecules into kaempferol. The structural analysis of BcGT-1 showed that its substrate binding site is wider than that of plant flavonoid monoglucosyltransferases. In order to create monoglucosyltransferase from BcGT-1, the error-prone polymerase chain reaction (PCR) was performed. We analyzed 150 clones. Among them, two mutants generated only kaempferol O-monoglucoside, albeit with reduced reactivity. Unexpectedly, the two mutants harbored mutations in the amino acids located outside of the active sites. Based on the modeled structure of BcGT-1, it was proposed that the local change in the secondary structure of BcGT-1 caused the alteration of triglucosyltransferase into monoglucosyltransferase.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1147-1150
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• 2011

Xanthomonas oryzae causes rice bacterial blight, which has been reported as one of the most destructive diseases of rice. Metabolites were identified through cheonggukjang, a traditional Korean fermented soybean product fermented by the Bacillus spp., to control the bacteria. HPLC, MS, and UPLC-Q-TOF-MS analyses were performed to identify metabolites responsible for antimicrobial activity. In this analysis, the m/z values of 253.0498, 283.0600, 269.0455, 992.6287, and 1,006.6436 were identified as daidzein, glycitein, genistein, surfactin B, and surfactin A, respectively. The levels of surfactin B and surfactin A were found to be high at 24 h (4.35 ${\mu}g$/ml) and 36 h (3.43 ${\mu}g$/ml) of fermentation, respectively.