• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1547-1552
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• 2009

Sphingomonas chungbukensis DJ77 has the ability to produce large quantities of an extracellular polysaccharide that can be used as a gelling agent in the food and pharmaceutical industries. We identified, cloned and expressed the UDP-glucose dehydrogenase gene of S. chungbukensis DJ77, and characterized the resulting protein. The purified UDP-glucose dehydrogenase (UGDH), which catalyzes the reversible conversion of UDP-glucose to UDPglucuronic acid, formed a homodimer and the mass of the monomer was estimated to be 46 kDa. Kinetic analysis at the optimal pH of 8.5 indicated that the $K_m\;and\;V_{max}$ for UDP-glucose were 0.18 mM and 1.59 mM/min/mg, respectively. Inhibition assays showed that UDP-glucuronic acid strongly inhibits UGDH. Site-directed mutagenesis was performed on Gly9, Gly12 Thr127, Cys264, and Lys267. Substitutions of Cys264 with Ala and of Lys267 with Asp resulted in complete loss of enzymatic activity, suggesting that Cys264 and Lys267 are essential for the catalytic activity of UGDH.

• 미생물학회지
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• 제34권4호
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• pp.207-211
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• 1998

메탄올을 이용하여 성장하는 Methylovorus sp. strain SS1은 formaldehyde의 산화를 위한 linear route의 주효소인 $NAD^+$-linked formaldehyde dehydrogenase 및 $NAD^+$-linked formate dehydrogenas와 cyclic route의 주효소인 hexulose-6-phosphate synthase, glucose-6-phosphate isomerae, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase 등의 활성을 나타내었는데, cyclic route에 관여하는 효소의 활성이 상대적으로 더 높았다. 이 세균은 formaldehyde의 동화와 관련된 ribulose monophosphate 경로의 주효소와 Entner-Doudoroff 경로의 주효소 및 transaldolase 활성과 함께 세포외 다당류 합성과 관련된 phosphoglucomutase, UDP-glucose pyrophyosphorylase, mannose-6-phosphate isomerase의 활성도 나타내었다. 2.3 mM의 ammonium sulfate가 포함된 배지에서 성장한 세균은 7.6 mM의 ammonium sulfate가 포함된 배지에서 성장한 세균보다 더 많은 세포외 다당류를 생산하였지만 균체 수율은 낮았고, 6-phosphogluconate dehydrogenase와 phosphoglucomutase 및 UDP-glucose pyrophoshorylase의 활성은 높게 나타내었으나 6-phosphogluconate dehydratase/2-keto-3-deoxy-6-phosphogluconate aldolase의 활성은 낮았다.

• BMB Reports
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• 제40권5호
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• pp.690-696
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• 2007

There are conflicting views for the polymerization process of human UDP-glucose dehydrogenase (UGDH) and no clear evidence has been reported yet. Based on crystal coordinates for Streptococcus pyogenes UGDH, we made double mutant A222Q/S233G. The double mutagenesis had no effects on expression, stability, and secondary structure. Interestingly, A222Q/S233G was a dimeric form and showed an UGDH activity, although it showed increased $K_m$ values for substrates. These results suggest that Ala222 and Ser233 play an important role in maintaining the hexameric structure and the reduced binding affinities for substrates are attributable to its altered subunit communication although quaternary structure may not be critical for catalysis.

• Journal of Microbiology and Biotechnology
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• 제12권2호
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• pp.217-221
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• 2002

dTDP-D-glucose 4,6-dehydratase (TDPDH) catalyzes the conversion of dTDP-D-glucose to dTDP-4-keto-6-deoxy-D-glucose, and requires $NAD^＋$ as a coenzyme for its catalytic activity. The dTDP-D-glucose 4,6-dehydratase from Streptomyces antibioticus $Tu{\ddot}99$ tightly binds $NAD^＋$ [19]. In order to determine the role of lysine-148 in the $NAD^＋$ binding, the lysine of the dTDP-D-glucose 4,6-dehydratase from Streptomyces antibioticus $Tu{\ddot}99$ was mutated to various amino acids by site-directed mutagenesis. The catalytic activity of the four mutated enzymes of TDPDH did not recover after addition of $NAD^＋$ . However, the activity of K159A, the mutated enzyme of UDP-D-glucose 4-epimerase (UDPE), recovered after the addition of $NAD^＋$ [15]. Although dTDP-glucose 4,6-dehydratase, and UDP-galactose (glucose) 4-epimerase are members of the short-chain dehydrogenase/reductase SDR family and the lysine-148 of TDPDH was highly conserved as in UDPE (Lys-159), the function of the lysine-148 of TDPDH was different from that of UDPE. The mutated enzymes showed that the lysine-148 of the dTDP-D-glucose 4,6-dehydratase played no role in the $NAD^＋$ binding. Accordingly, it is suggested that the lysine-148 of the dTDP-D-glucose 4,6-dehydratase is involved in the folding of TDPDH.

• Molecules and Cells
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• 제28권4호
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• pp.397-401
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• 2009

Flavonoids are a group of polyphenolic compounds that have been recognized as important due to their physiological and pharmacological roles and their health benefits. Glycosylation of flavonoids has a wide range of effects on flavonoid solubility, stability, and bioavailability. We previously generated the E. coli BL21 (DE3) ${\Delta}pgi$ host by deleting the glucose-phosphate isomerase (Pgi) gene in E. coli BL21 (DE3). This host was further engineered for whole-cell biotransformation by integration of galU from E. coli K12, and expression of calS8 (UDP-glucose dehydrogenase) and calS9 (UDP-glucuronic acid decarboxylase) from Micromonospora echinospora spp. calichensis and arGt-4 (7-O-glycosyltransferase) from Arabidopsis thaliana to form E. coli (US89Gt-4), which is expected to produce glycosylated flavonoids. To test the designed system, the engineered host was fed with naringenin as a substrate, and naringenin 7-O-xyloside, a glycosylated naringenin product, was detected. Product was verified by HPLC-LC/MS and ESI-MS/MS analyses. The reconstructed host can be applied for the production of various classes of glycosylated flavonoids.

• 생약학회지
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• 제24권2호
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• pp.153-158
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• 1993

As a part of pharmacological studies of saikosaponins, which were reported to exhibit diverse biological activities especially concerning with liver function, effects of saikosaponin on metabolizing enzymes and lipid peroxide contents in liver were examined. As the result, UDP-glucose dehydrogenase activity and lipid peroxidation which were due to acetaminophen were inhibited by saikosaponin treatment. But other metabolizing enzyme activities were not modified.

• 대한약리학회지
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• 제21권1호
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• pp.1-11
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• 1985

이물질(xenobiotics) 대사에 관여하는 간장 microsome과 cytosol 효소 활성에 indole, indole-3-carbinol 및 benzofuran이 미치는 영향을 검색하기위하여 마우스에 이들 약물을 각각 5 mmole/kg씩 10일간 투여하여 다음 몇 가지의 성적을 얻었다. Benzofuran은 microsome 효소인 aniline hydroxylase, 7-ethoxycoumarin O-deethylase, p-nitrophenol UDPGA-transferase, epoxide hydrolase와 cytosol 효소인 glutathione S-tranferase, NADH : quinone reductase, UDP-glucose dehydrogenase의 활성도를 증가시켰다. 그러나 benzofuran과는 구조적으로 furan ring내의 N원소가 O원소로 치환되었을 뿐 주된 구조가 유사한 indole과 indole-3-carbinol 투여로는 UDPGA-transferase와 NADH: quinone reductase의 활성도 증가를 볼 수 없었으며, 특히 indole은 NADPH : cytochrome C reductase만을 증가시킨데 비하여 구조상 indole에 carbinol (methanol)기가 붙은 indole-3-carbinol은 수종의 mixed function oxidase와 아울러 특히 epoxide hydrolase의 활성도 역시 증가시켰다. 이러한 결과는 benzofuran과 indole-3-carbinol에 의한 epoxide hydrolase 활성도 증가의 기전의 일부를 설명할 수 있을 것으로 생각된다.