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Now showing items 129 - 144 of 362

  • Natural rubber blends with epoxidized natural rubber

    Lee, Sang Yup   Kim, Joon Hyung   Kim, Byung Kyu  

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  • MEASURING THE ACTIVE AND PASSIVE CHARACTERISTICS OF CONTRACTILE SMOOTH MUSCLE IN PORCINE INTESTINE MODEL

    Jeen, Yoon Tae   Lee, Jung Min   Choi, Byeong Kwang   Lee, Sang Yup   Yoo, In Kyung   Kim, Seung Han   Choi, Hyuk Soon   Kim, Eun Sun   Keum, Bora   Lee, Hongsik   Kim, Chang Duck   Lee, Jae Min   Kim, Hunhee   Hong, Junghwa  

    Background and Aim: Electrical stimulation therapy is a new way to treat digestive disorders such as constipation, colonic inertia. It is necessary to understand the physiology of smooth muscle contraction in developing novel medical devices related with electrical stimulation therapy. The aims of this study were to measure the active characteristics of smooth muscle with acetylcholine in porcine intestine segment. Methods: We used five female pigs and obtained ten centimeters of each porcine small intestine. To measure passive characteristics of small intestine, a universal testing machine with a tensile rate of 30 mm/min. To estimate the active characteristic parameters of smooth muscle and isometric and isotonic intestinal motility of smooth muscle, muscle contraction was induced by applying the stimulation solution (HTK solution containing 1mM of acetylcholine chloride). Then, we obtained the maximum muscle contractile force of the specimens to measure the isometric and isotonic intestinal motility. Results: In tensile test, the maximum repulsive force, that indicate passive muscle force of smooth muscle 0.702 N, was measured. In the isometric and isotonic contractions in the porcine small intestine, the maximum myotility, 12.35 mN, was obtained in isometric experiments, and the maximum velocity of muscular contraction, 0.4476 mm/min, was obtained in isotonic experiments. We demonstrated that in equal lengths, the muscle contraction velocity of the smooth muscle is 10-100 times slower than that of the skeletal muscle indicating force-velocity relationship of smooth muscle. And we obtained that the maximum contraction force from each individual percentage of active force (25%, 50%, and 100%) was achieved at L/L-opt =3D 1. Conclusions: We straighten out the active and passive property of porcine intestinal smooth muscle. Our study may be helpful for developing novel medical devices and understanding the physiology of smooth muscle in the porcine small intestine.
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  • Antecedents of impression management motivations on social network sites and their link to social anxiety

    Lee, Sang Yup   Jang, Kyungeun  

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  • Metabolic Engineering of Escherichia coli for the Production of Hyaluronic Acid From Glucose and Galactose

    Woo, Ji Eun   Seong, Hyeon Jeong   Lee, Sang Yup   Jang, Yu-Sin  

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  • Repurposing type III polyketide synthase as a malonyl-CoA biosensor for metabolic engineering in bacteria.

    Yang, Dongsoo   Kim, Won Jun   Yoo, Seung Min   Choi, Jong Hyun   Ha, Shin Hee   Lee, Mun Hee   Lee, Sang Yup  

    Malonyl-CoA is an important central metabolite for the production of diverse valuable chemicals including natural products, but its intracellular availability is often limited due to the competition with essential cellular metabolism. Several malonyl-CoA biosensors have been developed for high-throughput screening of targets increasing the malonyl-CoA pool. However, they are limited for use only in Escherichia coli and Saccharomyces cerevisiae and require multiple signal transduction steps. Here we report development of a colorimetric malonyl-CoA biosensor applicable in three industrially important bacteria: E. coli, Pseudomonas putida, and Corynebacterium glutamicum RppA, a type III polyketide synthase producing red-colored flaviolin, was repurposed as a malonyl-CoA biosensor in E. coli Strains with enhanced malonyl-CoA accumulation were identifiable by the colorimetric screening of cells showing increased red color. Other type III polyketide synthases could also be repurposed as malonyl-CoA biosensors. For target screening, a 1,858 synthetic small regulatory RNA library was constructed and applied to find 14 knockdown gene targets that generally enhanced malonyl-CoA level in E. coli These knockdown targets were applied to produce two polyketide (6-methylsalicylic acid and aloesone) and two phenylpropanoid (resveratrol and naringenin) compounds. Knocking down these genes alone or in combination, and also in multiple different E. coli strains for two polyketide cases, allowed rapid development of engineered strains capable of enhanced production of 6-methylsalicylic acid, aloesone, resveratrol, and naringenin to 440.3, 30.9, 51.8, and 103.8 mg/L, respectively. The malonyl-CoA biosensor developed here is a simple tool generally applicable to metabolic engineering of microorganisms to achieve enhanced production of malonyl-CoA-derived chemicals.=20
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  • Recent advances in polyhydroxyalkanoate production by bacterial fermentation: mini-review

    Lee, Sang Yup   Choi, Jong-il   Wong, Heng Ho  

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  • METHOD FOR EXTRACELLULAR PRODUCTION OF TARGET PROTEINS BY CO-EXPRESSION OF OMPF AND TARGET PROTEINS

    The present invention relates to a method for secreting and producing a target protein into cell culture broth. More particularly, the invention relates to a microorganism co-transformed with a recombinant expression vector containing E. coli outer membrane protein F (OmpF) and a recombinant expression vector containing a target protein to be secreted into cell culture broth, as well as a method of secreting and producing the target protein into cell culture broth by culturing the microorganism. According to the invention, the target protein can be secreted into cell culture broth in a pure form without fusion with other proteins so that the efficient isolation and purification of the target protein is possible.
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  • Fed-batch culture of Escherichia coli for L-valine production based on in silico flux response analysis.

    Park, Jin Hwan   Kim, Tae Yong   Lee, Kwang Ho   Lee, Sang Yup  

    We have previously reported the development of a 100% genetically defined engineered Escherichia coli strain capable of producing L-valine from glucose with a high yield of 0.38g L-valine per gram glucose (0.58mol L-valine per mol glucose) by batch culture. Here we report a systems biological strategy of employing flux response analysis in bioprocess development using L-valine production by fed-batch culture as an example. Through the systems-level analysis, the source of ATP was found to be important for efficient L-valine production. There existed a trade-off between L-valine production and biomass formation, which was optimized for the most efficient L-valine production. Furthermore, acetic acid feeding strategy was optimized based on flux response analysis. The final fed-batch cultivation strategy allowed production of 32.3g/L L-valine, the highest concentration reported for E. coli. This approach of employing systems-level analysis of metabolic fluxes in developing fed-batch cultivation strategy would also be applicable in developing strategies for the efficient production of other bioproducts. Copyright 2010 Wiley Periodicals, Inc.
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  • Metabolic Engineering of Escherichia Coli for the Production of Polyhydroxyalkanoates

    Lee, Sang Yup   Choi, Jong-il  

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  • Microfluidic cell disruption system employing a magnetically actuated diaphragm (vol 28, pg 4748, 2007)

    Huh, Yun Suk   Choi, Jong Hyun   Kim, Kyoung Ae   Park, Tae Jung   Hong, Yeon Ki   Kim, Do Hyun   Hong, Won Hi   Lee, Sang Yup  

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  • Metabolic engineering of Escherichia coli for the production of 1,3-diaminopropane, a three carbon diamine.

    Chae, Tong Un   Kim, Won Jun   Choi, Sol   Park, Si Jae   Lee, Sang Yup  

    Bio-based production of chemicals from renewable resources is becoming increasingly important for sustainable chemical industry. In this study, Escherichia coli was metabolically engineered to produce 1,3-diaminopropane (1,3-DAP), a monomer for engineering plastics. Comparing heterologous C4 and C5 pathways for 1,3-DAP production by genome-scale in silico flux analysis revealed that the C4 pathway employing Acinetobacter baumannii dat and ddc genes, encoding 2-ketoglutarate 4-aminotransferase and L-2,4-diaminobutanoate decarboxylase, respectively, was the more efficient pathway. In a strain that has feedback resistant aspartokinases, the ppc and aspC genes were overexpressed to increase flux towards 1,3-DAP synthesis. Also, studies on 128 synthetic small RNAs applied in gene knock-down revealed that knocking out pfkA increases 1,3-DAP production. Overexpression of ppc and aspC genes in the pfkA deleted strain resulted in production titers of 1.39 and 1.35gl(-1) of 1,3-DAP, respectively. Fed-batch fermentation of the final engineered E. coli strain allowed production of 13gl(-1) of 1,3-DAP in a glucose minimal medium. =20
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  • The antiSMASH database,a comprehensive database of microbial secondary metabolite biosynthetic gene clusters

    Blin, Kai   Medema, Marnix H.   Kottmann, Renzo   Lee, Sang Yup   Weber, Tilmann  

    Secondary metabolites produced by microorganisms are the main source of bioactive compounds that are in use as antimicrobial and anticancer drugs, fungicides, herbicides and pesticides. In the last decade, the increasing availability of microbial genomes has established genome mining as a very important method for the identification of their biosynthetic gene clusters (BGCs). One of the most popular tools for this task is antiSMASH. However, so far, antiSMASH is limited to de novo computing results for user-submitted genomes and only partially connects these with BGCs from other organisms. Therefore, we developed the antiSMASH database, a simple but highly useful new resource to browse antiSMASH-annotated BGCs in the currently 3907 bacterial genomes in the database and perform advanced search queries combining multiple search criteria. antiSMASH-DB is available at http://antismash-db.secondarymetabolites.org/.
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  • Controllable gold-capped nanoporous anodic alumina chip for label-free,specific detection of bacterial cells

    Kim, Do-Kyun   Kim, Dong Min   Yoo, Seung Min   Lee, Sang Yup  

    We describe the development of a gold-capped nanostructured porous anodic alumina (PAA) chip, which makes use of localized surface plasmon resonance and interferometry for the label-free and specific detection of pathogenic bacterial cells via changes in relative reflected intensity (RRI) and wavelength shift. This chip is composed of PAA and gold layers that provide a reproducible and sensitive RRI and wavelength shift. We investigated the effects of varying the thicknesses of the PAA and gold layers on the optical responses of the chip. With this chip, we successfully detected and identified Pseudomonas aeruginosa in a proof-of-concept experiment; this chip can detect bacterial cells in a quantitative manner with a detection limit of 20 CFU per assay. Further, this chip based system can clearly identify target bacterial species in a multiplexed mode with high specificities on a single chip, so will be useful for the detection of various pathogenic microbes.
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  • METHOD FOR PRODUCING METAL NANOPARTICLES AND METALLIC SULFIDE NANOPARTICLES USING RECOMBINANT MICROORGANISMS

    The present invention relates to a method for producing metal nanoparticles and metal sulfide nanoparticles using recombinant microorganisms in which phytochelatin synthase and metallothionein are simultaneously expressed as heavy metal adsorption proteins, and a use of metal nanoparticles or metallic sulfide nanoparticles synthesized by the method. According to the present invention, by providing a method for synthesizing metal in the form of nanoparticles, in which the metal was difficult to synthesize by a conventional biological method, it is possible to synthesize metal nanoparticles in an eco-friendly and economical manner, and it is also possible to synthesize metal sulfide nanoparticles using metal and sulfur, and furthermore, the metal nanoparticles conventionally produced by a chemical or biological method significantly increase in yield by using the production method of the present invention.
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  • MUTANT MICROORGANISM HAVING HIGH PRODUCTION OF CADAVERINE, AND PREPARATION METHOD OF CADAVERINE USING SAME

    The present invention relates to a mutant microorganism having a high production of cadaverine, a preparation method of cadaverine using the same, and more specifically, to a mutant microorganism having a high production of cadaverine in which a gene involved in the degradation or use pathway of cadaverine is weakened or deleted, and a method for preparing putrescine in a high yield by cultivating the same under aerobic conditions. According to the present invention, the mutant microorganism having a high production of cadaverine is useful for preparing cadaverine, which is widely used by industries, in a high yield.
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  • A METHOD FOR PRODUCING HYDROXYCARBOXYLIC ACIDS BY AUTO-DEGRADATION OF POLYHYDROXYALKANOATES

    The present invention provides a method for producing optically active hydroxycarboxylic acid monomers by auto-degradation of polyhydroxyalkanoates (PHAs). In particular, the present invention provides a method for producing hydroxycarboxylic acid monomers (mostly optically active in (R)-(-)-configuration) comprising the steps of: (a) synthesizing and accumulating PHAs by culturing various microorganisms; and (b) preparing optically active hydroxycarboxylic acids which are monomers of PHAs, by auto-degradation of PHAs by keeping the cultured microorganism in a degradation solution such as water, salt solution, mixture of water and organic solvents, and buffer solution. The present invention also provides a method for the separation of the prepared (R)-(-)-hydroxycarboxylic acids using liquid chromatography (LC) or high performance liquid chromatography (HPLC), and also provides further purification method by removing impurities from the purely separated (R)-(-)-hydroxycarboxylic acids by organic solvent extraction and powder-making process of drying the purified hydroxycarboxylic acids. The present method is economical since hydroxycarboxylic acids can be efficiently produced with high purity and yield by simple process. Also, the present method is environmentally friendly since organic solvents, which are required in large amounts in conventional methods, are used only in minimal amounts in the present invention.
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