http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Simkhada, Dinesh,Oh, Tae-Jin,Kim, Eui Min,Yoo, Jin Cheol,Sohng, Jae Kyung Kluwer Academic Publishers 2009 Biotechnology letters Vol.31 No.1
<P>The deoxysugar biosynthetic gene cluster of calicheamicin contains the calS7, which encodes glucose-1-phosphate nucleotidyltransferase and converts glucose-1-phosphate and nucleotides (NTP) to NDP-glucose and pyrophosphate. calS7 was expressed in Escherichia coli BL21(DE3), and the purified protein had significant thymidylyltransferase and uridylyltransferase activities as well, with some guanidylyltransferase activity but negligible cytidyl and adenyltransferase activity. The functions of thymidylyltransferase and uridylyltransferase were also verified using one-pot enzymatic synthesis of TMK and ACK. The products were analyzed by HPLC and ESI/MS, which showed peaks at m/z = 563 and 565 for TDP-D: -glucose and UDP-D-glucose, respectively, in negative mode.</P>
A New Thermolabile Alkaline Phospholipase D from Streptomyces sp. CS628
Simkhada, Jaya Ram,Cho, Seung-Sik,Choi, Hong-Seok,Kim, Si-Wouk,Lee, Hei-Chan,Sohng, Jae-Kyung,Yoo, Jin-Cheol 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.4
A phospholipase D ($PLD_{628}$), constitutively secreted by Streptomyces sp. CS628, was purified by ion exchange with CM Trisacryl and gel filtration with Sepharose CL-6B. The enzyme production was highest with peptone and starch as nitrogen and carbon sources, and at $30^{\circ}C$ with an initial medium pH of 7.5. Molecular weight, optimum pH, optimum temperature, pH stability, and thermostability of the enzyme were 50 kDa, pH 9.6, $30^{\circ}C$, pH 5.7 ~ 10.6 and ${\leq}30^{\circ}C$, respectively. Detergents and metal ions had varied effects on the enzyme activity. Importantly, $PLD_{628}$ could not catalyze transphosphatidylation of glycerol, L-serine, myo-inositol or ethanolamine, which are extensively used to assess the activity, suggesting that $PLD_{628}$ lacks the transphosphatidylation activity. $PLD_{628}$ could be a novel PLD based on its biochemical characteristics, which are significantly different from previously reported PLDs, such as thermolability, highest activity at alkaline pH, and lack of transphosphatidylation activity.
Simkhada, Jaya Ram,Cho, Seung-Sik,Lee, Hyo-Jung,Yoo, Jin-Cheol 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.10
Streptomyces sp. CS-57, which was isolated from Korean soil, was found to produce phospholipase D ($PLD_{57}$) as an extracellular enzyme when cultured in medium containing 2% glucose, 1.5% yeast extract, 0.5% trypton, and 0.1% calcium carbonate at $28^{\circ}C$, and 160-rpm. $PLD_{57}$ was purified using Sepharose CL-6B column chromatography, and DEAE-Sepharose CL-6B ion exchange column chromatography. The specific activity of the purified enzyme increased 6.7 fold with 3% recovery. The purified enzyme was then analyzed using 12% SDS-PAGE, which revealed that the molecular mass of the purified enzyme was 55 kDa. $PLD_{57}$ showed both hydrolytic (H) and transphosphatidylation (T) activity, and the optimum temperatures of these activities were found to be $45^{\circ}C\;and\;35^{\circ}C$, respectively. Similarly, both of these activities were found to be optimal at a pH of 7.5. In addition, even after being heat treated at $45^{\circ}C$ for up to 2 h, the enzyme activity remained at 100%, and the H-activity was found to be stable at a pH of 6 to 8. Further, enzyme activity occurred in the presence of EDTA, indicating that metal ions are not required for their activity, although some metal ions did marginally increase the activity. Enzyme activity also increased by 75% in the presence of Triton-X 100 at a concentration of 0.375 %; however, none of the other detergents evaluated in this study were found to enhance enzyme activity.
Simkhada, Jaya Ram,Yoo, Hah-Young,Choi, Yun Hee,Kim, Seung Wook,Yoo, Jin Cheol Humana Press 2012 Applied biochemistry and biotechnology Vol.168 No.7
<P>Streptomyces sp. CS802, recently isolated from Korean soil, produced xylanase in corncob medium. An extracellular xylanase (Xyn802) was purified by a single-step gel filtration and biochemical properties were studied. It showed high activity in extremely alkaline condition with optimum pH at 12.0 and exhibited stability between pH?7.5 and 13.0. It produced xylobiose and xylotriose as the major products from xylan, suggesting its endoxylanase nature. N-terminal amino acid sequences of Xyn802 were ADRNANRD which are significantly different from the reported xylanase. The activity was enhanced by various detergents and a reducing agent and stable in various organic solvents. Xyn802 produced by utilizing corncob, an agro-waste material, might be a novel xylanase based on its peculiar biochemical characteristics, and it can be a suitable candidate for the production of xylooligosaccharides including other useful products.</P>
Metabolic Engineering of Escherichia coli for the Biological Synthesis of 7-O-Xylosyl Naringenin
Dinesh Simkhada,EuiMin Kim,Hei Chan Lee,송재경 한국분자세포생물학회 2009 Molecules and cells Vol.28 No.4
Flavonoids are a group of polyphenolic compounds that have been recognized as important due to their physio-logical and pharmacological roles and their health benefits. Glycosylation of flavonoids has a wide range of effects on flavonoid solubility, stability, and bioavailability. We previ-ously generated the E. coli BL21 (DE3) Δpgi host by delet-ing 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 dehydro-genase) 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.
Exploration of Glycosylated Flavonoids from Metabolically Engineered E. coli
Dinesh Simkhada,Nagendra Prasad Kurumbang,Hei Chan Lee,송재경 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.5
Flavonoids glycosylated with UDP-glucuronic acid and UDP-xylose are spatially distributed in nature. To produce these glycosides, E. coli was engineered to overexpress biosynthetic gene clusters of UDP-sugars (galU from E. coli K12, UDP-glucose dehydrogenase (calS8),and UDP-glucuronic acid decarboxylase (calS9) from Micromonospora echinospora spp. calichensis). Flavonoids were glycosylated by overexpression of the glycosyltransferase gene (atGt-5) from Arabidopsis thaliana. Finally, metabolically engineered host E. coli (US89Gt-5) was generated. Production of flavonoid glycosides was observed in a biotransformation system consisting of flavonoids (naringenin and quercetin) exogenously fed to host cells. The glycosylated derivatives 7-O-glucuronyl naringenin (m/z+449), 7-O-xylosyl naringenin (m/z+ 405), and 7-O-glucuronyl quercetin (m/z+ 479) were detected and confirmed by ESI-MS/MS, ESI-MS/MS and LC/MS-MS analysis, respectively.