The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform
Tsuei-yun Fang - One of the best experts on this subject based on the ideXlab platform.
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Characterization of a thermophilic L-rhamnose isomerase from Caldicellulosiruptor saccharolyticus ATCC 43494.
Journal of agricultural and food chemistry, 2011Co-Authors: Chia-jui Lin, Wen-chi Tseng, Tsuei-yun FangAbstract:L-Rhamnose isomerase (EC 5.3.1.14, l-RhI) catalyzes the reversible aldose-ketose isomerization between L-rhamnose and L-rhamnulose. In this study, the L-rhi gene encoding L-RhI was PCR-cloned from Caldicellulosiruptor saccharolyticus ATCC 43494 and then expressed in Escherichia coli. A high yield of active L-RhI, 3010 U/g of Wet Cells, was obtained after 20 °C induction for 20 h. The enzyme was purified sequentially using heat treatment, nucleic acid precipitation, and ion-exchange chromatography. The purified L-RhI showed an apparent optimal pH of 7 and an optimal temperature at 90 °C. The enzyme was stable at pH values ranging from 4 to 11 and retained >90% activity after a 6 h incubation at 80 °C and pH 7-8. Compared with other previously characterized L-RhIs, the L-RhI from C. saccharolyticus ATCC 43494 has a good thermostability, the widest pH-stable range, and the highest catalytic efficiencies (k(cat)/K(M)) against L-rhamnose, L-lyxose, L-mannose, D-allose, and D-ribose, suggesting that this enzyme has the potential to be applied in rare sugar production.
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characterization of a thermophilic l rhamnose isomerase from thermoanaerobacterium saccharolyticum ntou1
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Chia-jui Lin, Wen-chi Tseng, Tienhsiang Lin, Shiumei Liu, Wenshyong Tzou, Tsuei-yun FangAbstract:L-Rhamnose isomerase (EC 5.3.1.14, L-Rhl) catalyzes the reversible aldose-ketose isomerization between L -rhamnose and L-rhamnulose. In this study, the L-rhi gene encoding L -Rhl was PCR-cloned from Thermoanaerohacterium saccharolyticum NTOU1 and then expressed in Escherichia coli. A high yield of the active L-Rhl, 9780 U/g of Wet Cells, was obtained in the presence of 0.2 mM IPTG induction. L -Rhl was purified sequentially using heat treatment, nucleic acid precipitation, and anion-exchange chromatography. The purified L -Rhl showed an apparent optimal pH of 7 and an optimal temperature at 75 °C. The enzyme was stable at pH values ranging from 5 to 9, and the activity was fully retained after a 2 h incubation at 40-70 °C. L -Rhl from T. saccharolyticum NTOU1 is the most thermostable L -Rhl to date, and it has a high specific activity (163 U/mg) and an acceptable purity after heat treatment, suggesting that this enzyme has the potential to be used in rare sugar production.
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expression purification and characterization of the maltooligosyltrehalose trehalohydrolase from the thermophilic archaeon sulfolobus solfataricus atcc 35092
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Tsuei-yun Fang, Wen-chi Tseng, Tongyuan Shih, Xingguang HungAbstract:The maltooligosyltrehalose trehalohydrolase (MTHase) mainly cleaves the α-1,4-glucosidic linkage next to the α-1,1-linked terminal disaccharide of maltooligosyltrehalose to produce trehalose and the maltooligosaccharide with lower molecular mass. In this study, the treZ gene encoding MTHase was PCR-cloned from Sulfolobus solfataricus ATCC 35092 and then expressed in Escherichia coli. A high yield of the active wild-type MTHase, 13300 units/g of Wet Cells, was obtained in the absence of IPTG induction. Wild-type MTHase was purified sequentially using heat treatment, nucleic acid precipitation, and ion-exchange chromatography. The purified wild-type MTHase showed an apparent optimal pH of 5 and an optimal temperature at 85 °C. The enzyme was stable at pH values ranging from 3.5 to 11, and the activity was fully retained after a 2-h incubation at 45−85 °C. The kcat values of the enzyme for hydrolysis of maltooligosyltrehaloses with degree of polymerization (DP) 4−7 were 193, 1030, 1190, and 1230 s-1, respect...
Kathryn Grandfield - One of the best experts on this subject based on the ideXlab platform.
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simultaneous visualization of Wet Cells and nanostructured biomaterials in sem using ionic liquids
ChemBioChem, 2021Co-Authors: Bryan E J Lee, Lizaanastasia Dicecco, Hourieh Exir, Arnaud Weck, Kyla N Sask, Kathryn GrandfieldAbstract:This work presents a successful methodology to image mammalian Cells adhered to nanostructured titanium by using scanning electron microscopy (SEM) operating in low-vacuum mode following ionic liquid treatment. Human osteoblast-like Saos-2 Cells were treated with a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, and subsequently imaged on titanium by SEM. Titanium substrates were modified to create laser-induced periodic surface structures (LIPSS) for visualization at the submicron scale. By using a combination of fluorescence-based cell metabolism along with light microscopy and SEM image analysis, the shape and location of irradiated Cells were confirmed to be unchanged after multiple irradiation sessions; the viability of minimally irradiated Cells was also unaltered. The Wet imaging conditions combined with a rapid facile protocol using ionic liquid allows this technique to fulfill a niche in examining cellular behavior on biomaterials with submicron surface features. The demonstrated method to track observed cell adhesion to submicron surface features by SEM has great implications for understanding cell migration on nanostructured surfaces as well as the exploration of simpler SEM preparation methods for cellular imaging.
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a facile method for simultaneous visualization of Wet Cells and nanostructured biomaterials in sem using ionic liquids
bioRxiv, 2020Co-Authors: Bryan E J Lee, Lizaanastasia Dicecco, Hourieh Exir, Arnaud Weck, Kyla N Sask, Kathryn GrandfieldAbstract:In schistosomiasis mansoni, soluble egg antigens of the worm induce chronic T-cell-mediated granulomatous tissue responses. Since the first preparation of crude soluble egg antigen extract, a dearth of highly purified antigens has hampered the identification of granuloma inducer molecules. Here we report that a cloned 38-kDa egg polypeptide (r38) with homologies to small heat shock proteins is a strong immunogen. The recombinant and the sodium dodecyl sulfate-polyacrylamide gel electrophoresis separated and eluted native 38-kDa (p38) polypeptides, used in microgram amounts and unaided by adjuvant, sensitized mice for a Th1-type immune response, with strong interleukin-2 (IL-2) and gamma interferon secretion but no IL-4 and IL-10 secretion. Extensive cross-reactivity between these two polypeptides was evident. THis pattern was confirmed by reverse transcription-PCR that showed strong IL-2 and gamma interferon message expression but trace amounts of IL-4 message expression in r38-sensitized splenocytes. In mice, the polypeptide induced pulmonary mononuclear granuloma formation around antigen-coupled beads or worm eggs. We propose that the superior immunogenicity of r38 is linked to its relatedness to small heat shock proteins and that the 38-kDa polypeptide may induce the Th1 cytokine responses observed during the early development phase of the egg-induced granuloma.
G S De Hoog - One of the best experts on this subject based on the ideXlab platform.
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indoor Wet Cells harbour melanized agents of cutaneous infection
Medical Mycology, 2010Co-Authors: X Lian, G S De HoogAbstract:The biota of black fungi in humid indoor environments was established using a protocol that consisted of non-selective and selective isolation procedures. In total, 113 samples were taken from bathrooms of residences in The Netherlands, Germany and Austria. Samples were processed either (i) directly by culturing on agar media, or (ii) by pre-incubating samples for enrichment in mineral solutions with perlite granules under constant toluene atmosphere for three months. Dilutions from the latter were then cultured and incubated as were those directly plated to agar media. Black colonies were selected and identified by sequencing the rDNA Internal Transcribed Spacer (ITS) region. Twenty-eight strains of black fungi were found in 26 positive samples without enrichment, and 42 strains were isolated from 38 positive samples after enrichment in toluene. The great majority of black fungal species were members of the order Chaetothyriales, which is the main order of melanized human opportunistic pathogens. Cladosporium species (Capnodiales) were the most frequent isolates when no enrichment was applied, as opposed to Exophiala species (Chaetothyriales) with enrichment. The enrichment method provides insight into a fungal biota commonly occurring in homes which has previously been overlooked. Several species have been previously known only from cutaneous infections and could suggest that bathrooms are a likely reservoir of these fungi.
Eman Afkar - One of the best experts on this subject based on the ideXlab platform.
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localization of the dissimilatory arsenate reductase in sulfurospirillum barnesii strain ses 3
American Journal of Agricultural and Biological Sciences, 2012Co-Authors: Eman AfkarAbstract:Problem statement: Sulfurospirillim barnesii strain SeS-3 is one of the recently known bacterial isolates that can obtain energy to support growth by respiring the toxic oxyanions of arsenic and selenium under anaerobic conditions. Approach: The ultimate goal of this investigation is to localize the active sites for the reduction of arsenate arsenite as well as selenate selenite in S. barnesii strain SeS-3. Results: The ability of the type strain Sulfurospirillium barnesii strain SES-3 (ATCC 700032) to reduce selenate and arsenate were tested using cell grown anaerobically with 20 mM lactate as the carbon source and either 10 mM selenate or 5 mM arsenate as the terminal electron acceptors were harvested after the turbidity reached 0.3, 0.4 absorption units at 600 nm, cell density 4gm Wet Cells. The results of this study showed that the mobilization of the toxic oxyanions of arsenic and selenium by Sulfurospirillum barnesii strain SES-3 is linked to the membrane. The enzyme is specific for the reduction of arsenate, selenate, selenite, nitrite, thiosulfate and phosphate. Whereas, no specificity was detected for arsenite nitrate, fumarate, when they served as the final electron acceptor. Conclusion/Recommendations: This study concluded that the mechanism of arsenate reduction by S.barnesii strain SeS-3 is connected into the membrane. The environmental significance of this bacterium and its impact to the bioremediation potential in the underground water and sedimentary environment is also discussed.
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localization of the dissimilatory arsenate reductase in sulfurospirillum barnesii strain ses 3
American Journal of Agricultural and Biological Sciences, 2012Co-Authors: Eman AfkarAbstract:Problem statement: Sulfurospirillim barnesii strain SeS-3 is one of the recently known bacterial isolates that can obtain energy to support growth by respiring the toxic oxyanions of arsenic and selenium under anaerobic conditions. Approach: The ultimate goal of this investigation is to localize the active sites for the reduction of arsenate arsenite as well as selenate selenite in S. barnesii strain SeS-3. Results: The ability of the type strain Sulfurospirillium barnesii strain SES-3 (ATCC 700032) to reduce selenate and arsenate were tested using cell grown anaerobically with 20 mM lactate as the carbon source and either 10 mM selenate or 5 mM arsenate as the terminal electron acceptors were harvested after the turbidity reached 0.3, 0.4 absorption units at 600 nm, cell density 4gm Wet Cells. The results of this study showed that the mobilization of the toxic oxyanions of arsenic and selenium by Sulfurospirillum barnesii strain SES-3 is linked to the membrane. The enzyme is specific for the reduction of arsenate, selenate, selenite, nitrite, thiosulfate and phosphate. Whereas, no specificity was detected for arsenite nitrate, fumarate, when they served as the final electron acceptor. Conclusion/Recommendations: This study concluded that the mechanism of arsenate reduction by S.barnesii strain SeS-3 is connected into the membrane. The environmental significance of this bacterium and its impact to the bioremediation potential in the underground water and sedimentary environment is also discussed.
Chia-jui Lin - One of the best experts on this subject based on the ideXlab platform.
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Characterization of a thermophilic L-rhamnose isomerase from Caldicellulosiruptor saccharolyticus ATCC 43494.
Journal of agricultural and food chemistry, 2011Co-Authors: Chia-jui Lin, Wen-chi Tseng, Tsuei-yun FangAbstract:L-Rhamnose isomerase (EC 5.3.1.14, l-RhI) catalyzes the reversible aldose-ketose isomerization between L-rhamnose and L-rhamnulose. In this study, the L-rhi gene encoding L-RhI was PCR-cloned from Caldicellulosiruptor saccharolyticus ATCC 43494 and then expressed in Escherichia coli. A high yield of active L-RhI, 3010 U/g of Wet Cells, was obtained after 20 °C induction for 20 h. The enzyme was purified sequentially using heat treatment, nucleic acid precipitation, and ion-exchange chromatography. The purified L-RhI showed an apparent optimal pH of 7 and an optimal temperature at 90 °C. The enzyme was stable at pH values ranging from 4 to 11 and retained >90% activity after a 6 h incubation at 80 °C and pH 7-8. Compared with other previously characterized L-RhIs, the L-RhI from C. saccharolyticus ATCC 43494 has a good thermostability, the widest pH-stable range, and the highest catalytic efficiencies (k(cat)/K(M)) against L-rhamnose, L-lyxose, L-mannose, D-allose, and D-ribose, suggesting that this enzyme has the potential to be applied in rare sugar production.
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characterization of a thermophilic l rhamnose isomerase from thermoanaerobacterium saccharolyticum ntou1
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Chia-jui Lin, Wen-chi Tseng, Tienhsiang Lin, Shiumei Liu, Wenshyong Tzou, Tsuei-yun FangAbstract:L-Rhamnose isomerase (EC 5.3.1.14, L-Rhl) catalyzes the reversible aldose-ketose isomerization between L -rhamnose and L-rhamnulose. In this study, the L-rhi gene encoding L -Rhl was PCR-cloned from Thermoanaerohacterium saccharolyticum NTOU1 and then expressed in Escherichia coli. A high yield of the active L-Rhl, 9780 U/g of Wet Cells, was obtained in the presence of 0.2 mM IPTG induction. L -Rhl was purified sequentially using heat treatment, nucleic acid precipitation, and anion-exchange chromatography. The purified L -Rhl showed an apparent optimal pH of 7 and an optimal temperature at 75 °C. The enzyme was stable at pH values ranging from 5 to 9, and the activity was fully retained after a 2 h incubation at 40-70 °C. L -Rhl from T. saccharolyticum NTOU1 is the most thermostable L -Rhl to date, and it has a high specific activity (163 U/mg) and an acceptable purity after heat treatment, suggesting that this enzyme has the potential to be used in rare sugar production.
