Publications by authors named "Sun Ok Park"

3-Dehydroshikimate (DHS) is a useful starting metabolite for the biosynthesis of muconic acid (MA) and shikimic acid (SA), which are precursors of various valuable polymers and drugs. Although DHS biosynthesis has been previously reported in several bacteria, the engineered strains were far from satisfactory, due to their low DHS titers. Here, we created an engineered cell factory to produce a high titer of DHS as well as an efficient system for the conversion DHS into MA.

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The biological fermentation of plants is usually used to improve their product properties, including their biological activity. Acanthopanax koreanum is a plant indigenous to Jeju, Korea; however, fermented A. koreanum (FAK) has not been guaranteed to be safe.

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The antioxidant activity and chlorogenic acid and caffeic acid contents were investigated from different parts of Acanthopanax senticosus and A. koreanum. Antioxidant activity was assessed by various in vitro assays such as DPPH, ABTS, FRAP, reducing power assays and ORAC, and the chlorogenic acid and caffeic acid were validated by HPLC chromatography.

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The present study investigated the antibacterial effect of a bioprocessed polysaccharide (BPP) isolated from Lentinus edodes liquid mycelial culture supplemented with black rice bran against murine salmonellosis. BPP was not bactericidal in vitro, it did, however, stimulate uptake of the bacteria into RAW 264.7 murine macrophage cells, as indicated by increased colony-forming unit (CFU) counts of the contents of the lysed macrophages incubated with Salmonella Typhimurium for 30 and 60 min.

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Endotoxemia (sepsis, septic shock) is an inflammatory, virulent disease that results mainly from bacterial infection. The present study investigates the inhibitory effect of a bioprocessed polysaccharide (BPP) isolated from the edible Lentinus edodes liquid mycelial mushroom culture supplemented with black rice bran against murine endotoxemia induced by the Salmonella lipopolysaccharide and d-galactosamine (LPS/GalN). BPP was obtained after dialysis against water using a cellulose tube with a molecular weight cutoff of 10000.

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The quantitative determination of tetrahydrobiopterin (BH4) and its oxidized forms (dihydrobiopterin and biopterin) is important in searching for possible markers of neuropsychiatric and cardiovascular disorders as well as in diagnosing BH4 deficiencies. Currently, two high-performance liquid chromatography (HPLC) methods are available, although both have some limitations. We developed an enzymatic method to distinguish BH4 from the oxidized forms by employing BH4:UDP-glucose alpha-glucosyltransferase (BGluT), which catalyzes glucosyl transfer from UDP-glucose to BH4.

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Sepiapterin reductase from Chlorobium tepidum (cSR) catalyzes the synthesis of a distinct tetrahydrobiopterin (BH4), L-threo-BH4, different from the mammalian enzyme product. The 3-D crystal structure of cSR has revealed that the product configuration is determined solely by the substrate binding mode within the well-conserved catalytic triads. In cSR, the sepiapterin is stacked between two aromatic side chains of Phe-99 and Trp-196 and rotated approximately 180 degrees C around the active site from the position in mouse sepiapterin reductase.

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We investigated the in vitro effect of modified Je-Ho-Tang (MJHT) hot-water extract on platelet aggregation and activation induced by agonists in human whole blood, and on platelet adhesion to a collagen-coated surface under flow shear stress conditions. MJHT extract potently inhibited the collagen-induced platelet aggregation in human whole blood in a dose-dependent manner, with a half-maximal inhibitory dose (IC(50)) value of 526 microg/mL. We accessed several markers of platelet activation using receptor expression on platelet membranes, including GPIIb/IIIa-like expression (PAC-1) and P-selectin (CD62); we monitored the intracellular calcium mobilization response by flow cytometry in healthy subjects.

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A putative cellular function of tetrahydropteridines (l-erythro-tetrahydrobiopterin and d-threo-tetrahydrobiopterin) was investigated in Dictyostelium discoideum Ax2 using a mutant disrupted in the gene encoding sepiapterin reductase (SR). The SR mutant, which produces about 3% of tetrahydropteridines if compared to wild-type, was elucidated to have several functional defects related to mitochondria and oxidative stress: retarded growth, poor spore viability, impaired mitochondrial function, and increased susceptibility to oxidative stress induced by hydroxylamine or cumene-hydroperoxide. However, the physiological defects were almost completely rescued by extrachromosomal expression of Dictyostelium SR.

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Article Synopsis
  • Previous research indicated that a specific fragment of human fibronectin, called CCBD, helps osteoblasts attach and grow.
  • This study focuses on the heparin-binding domain (HBD) of fibronectin, which appears to boost the effects of CCBD on HOS cells.
  • Data shows that the HBD significantly improves cell adhesion and proliferation when combined with CCBD (P < 0.05).
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Transduction of cytokine gene into tumor cells is a promising method of tumor therapy, but the value is limited by accompanying side effects. To focus antitumor immune response to tumor antigen-specific CTL, we developed an antitumor vaccine by transfecting modified IL-2 gene in a membrane-bound form (mbIL-2) into B16F10 melanoma cells. The mbIL-2 clone showed reduced tumorigenicity and metastatic ability, and inhibited metastasis and prolonged the survival of mice against B16F10 cells.

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