• Journal of Plant Biotechnology
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• v.29 no.4
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• pp.265-275
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• 2002

Flavonoid biosynthesis is one of the most extensively studied areas in the secondary metabolism. Due to the study of flavonoid metabolism in diverse plant system, the pathways become the best characterized secondary metabolites and can be excellent targets for metabolic engineering. These flavonoid-derived secondary metabolites have been considerably divergent functional roles: floral pigment, anticancer, antiviral, antitoxin, and hepatoprotective. Three species have been significant for elucidating the flavonoid metabolism and isolating the genes controlling the flavonoid genes: maize (Zea mays), snapdragon (Antirrhinum majus) and petunia (Prtunia hybrida). Recently, many genes involved in biosynthesis of flavonoid have been isolated and characterized using mutation and recombinant DNA technologies including transposon tagging and T-DNA tagging which are novel approaches for the discovery of uncharacterized genes. Metabolic engineering of flavonoid biosynthesis was approached by sense or antisense manipulation of the genes related with flavonoid pathway, or by modified expression of regulatory genes. So, the use of a variety of experimental tools and metabolic engineering facilitated the characterization of the flavonoid metabolism. Here we review recent progresses in flavonoid metabolism: confirmation of genes, metabolic engineering, and applications in the industrial use.

• Applied Biological Chemistry
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• v.47 no.4
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• pp.390-395
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• 2004

In order to characterize ion channels present in tomato roots, microsomes were incorporated into an artificial lipid bilayer arranged for electrophysiological analysis. Of the five different ion channels that could be found, a channel of 450 pS conductance was found most frequently. This channel displayed subconductance states of 450, 257 and 105 pS. All subconductance states showed linear current-voltage relationships. At positive holding potentials, high frequency of transient channel openings was observed; however, at negative potentials, the open times were long and open probability high. Po was 0.83 at -40 mV. When an additional 50 mM $K^+\;or\;Na^+$ was added to the cis side of bilayer, the reversal potentials shifted in the negative direction to near -10 mV. Thus, the 450 pS cation channel selects poorly between $K^+\;and\;Na^+$. In the presence of $100\;{\mu}M$ metal ions, the channel activity was severely inhibited by $La^{3+},\;Ba^{2+},\;and\;Zn^{2+}$, and Po was decreased to 0.2 or even less. However, $Al^{3+}\;and\;Cd^{2+}$ decreased the activity by only 20%. Interestingly, each metal ion showed different kinetics of channel inhibition. While $500\;{\mu}M\;La^{3+}$ inhibited the activities of all subconductance state, 1 mM $Zn^{2+}$ inhibited all except the 105 pS state. $Cd^{2+}$ changed the gating of the channel from a long-opening state to brief transient openings even at negative holding potentials. These data represent that the metal ions may have different binding sites on the channel protein and could be useful modulators and probes to investigate structural characteristics as well as the functional roles of the 450 pS channel on the root physiology.

• Economic and Environmental Geology
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• v.53 no.4
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• pp.347-362
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• 2020

Iron (hydro)oxides in aqueous environments are primarily formed due to mining activities, and they are known to be typical colloidal particles disturbing surrounding environments. Among them, hematites are widespread in surface environments, and their behavior is controlled by diverse factors in aqueous environments. This study was conducted to elucidate the effect of environmental factors, such as ionic composition and strength, pH, and natural organic matter (NOM) on the behavior of colloidal hematite particles. In particular, two analytical methods, such as dynamic light scattering (DLS) and single-particle ICP-MS (spICP-MS), were compared to quantify and characterize the behavior of colloidal hematites. According to the variation of ionic composition and strength, the aggregation/dispersion characteristics of the hematite particles were affected as a result of the change in the thickness of the diffuse double layer as well as the total force of electrostatic repulsion and van der Walls attraction. Besides, the more dispersed the particles were, the farther away the aqueous pH was from their point of zero charge (PZC). The results indicate that the electrostatic and steric (structural) stabilization of the particles was enhanced by the functional groups of the natural organic matter, such as carboxyl and phenolic, as the NOM coated the surface of colloidal hematite particles in aqueous environments. Furthermore, such coating effects seemed to increase with decreasing molar mass of NOM. On the contrary, these stabilization (dispersion) effects of NOM were much more diminished by divalent cations such as Ca²⁺ than monovalent ones (Na⁺), and it could be attributed to the fact that the former acted as bridges much more strongly between the NOM-coated hematite particles than the latter because of the relatively larger ionic potential of the former. Consequently, it was quantitatively confirmed that the behavior of colloidal hematites in aqueous environments was significantly affected by diverse factors, such as ionic composition and strength, pH, and NOM. Among them, the NOM seemed to be the primary and dominant one controlling the behavior of hematite colloids. Meanwhile, the results of the comparative study on DLS and spICPMS suggest that the analyses combining both methods are likely to improve the effectiveness on the quantitative characterization of colloidal behavior in aqueous environments because they showed different strengths: the main advantage of the DLS method is the speed and ease of the operation, while the outstanding merit of the spICP-MS are to consider the shape of particles and the type of aggregation.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.167-173
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• 2007

To study the transcriptional mechanisms by which expression of the murine glial cell-derived neurotrophic factor inducible transcription factor (mGIF) gene is regulated, a murine genomic clone was iso-lated using a mGIF cDNA as probe. A 13-kb genomic fragment, which comprises 4-kb upstream of the transcription initiation site was sequenced. The promoter region lacks a TATA box and CAAT box, is rich in G+C content, and has multiple putative binding sites for the transcription factor Spl. The mGIF gene also has consensus sequences for AP2 binding sites. The transcriptional activity of five deletion mutants of a 2.1-kb fragment was analyzed by modulating transcription of the heterologous luciferase gene in the promoterless plasmid pGL2-Basic. All mutants showed significant transcriptional activity in the murine neuroblastoma cell line NB41A3. Transient expression assays suggested the presence of a positive regulator between -213 and -129 while a negative regulator was found in the region between -806 and -214. Relatively strong transcriptional activity was observed in neuronal NB41A3, glial C6 cells and hepatic HepG2, but very weak activity in skeletal muscle C2C12 cells. These findings confirm the tissue-specific activity of the mGIF promoter and suggest that this gene shares structural and functional similarities with the dopamine receptor genes that it regulates.

• Journal of Life Science
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• v.27 no.11
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• pp.1369-1375
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• 2017

The purpose of this study was to investigate the cellular characterization of phospholipase C-${\delta}1$ in olive flounders (Paralichthys olivaceus). In general, phospholipase C signaling pathways are distributed in nuclei at plasma membranes and in cytoplasms, although the pathways' nuclear localization mechanisms are unclear. P. olivaceus duplicates type-A PoPLC-${\delta}1$ (PoPLC-${\delta}1A$), which has a high similarity to the human isoform PLC-${\delta}$; type-B PoPLC-${\delta}1$ (PoPLC-${\delta}1B$ [Sf]), which has a low similarity to the human isoform PLC-${\delta}$ and the alternative splice variant PoPLC-${\delta}1B$ (Lf), which has a nuclear localization signal (NLS) and a nuclear export signal (NES) for nuclear imports and exports, respectively. This study confirmed the effects of the cellular localization and translocation of GFP-tagged PoPLC-${\delta}1A$, PoPLC-${\delta}1B$ (Sf) and PoPLC-${\delta}1B$ (Lf). It administered treatments of $Ca^{2+}$ ionophore ionomycin and endoplasmic reticulum (ER)-$Ca^{2+}$ pump inhibitor thapsigargin to hirame natural-embryo (HINAE) cells. A laser-scanning confocal microscope was used. GFP-tagged PoPLC-${\delta}1A$ was distributed to the cellular organelles, rather than to the cytoplasms and cytomembranes, when PoPLC-${\delta}1B$ (Lf) and PoPLC-${\delta}1B$ (Sf) were localized at the plasma membranes. The treatments of ionomycin and thapsigargin showed the accumulation of PoPLC-${\delta}1A$ in the nuclei when PoPLC-${\delta}1B$ (Lf) nucleocytoplasmic shuttling and PoPLC-${\delta}1B$ (Sf) nucleocytoplasmic shuttling were not observed. The results were the first evidence that PoPLC-${\delta}1A$, which contains functional, intact NES sequences, has a main role in nucleocytoplasmic shuttling and translocation in fish.

• Microbiology and Biotechnology Letters
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• v.45 no.1
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• pp.63-70
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• 2017

A functional screen of 60,672 fosmid metagenomic clones amplified from marine sediment obtained from the Dokdo islets in Korea identified the gene EstES1, whose product, EstES1, displayed lipolytic properties on tributyrin-supplemented media. EstES1 is a 576 amino acid protein with a predicted molecular weight of 59.4 kDa including 37 N-terminal leader amino acids. EstES1 exhibited the highest sequence similarity (44%) to a carboxylesterase found in Haliangium ochraceum DSM14365. Phylogenetic analysis indicated that EstES1 belongs to a currently uncharacterized family of lipases. Within the conserved domain, EstES1 retains the catalytic triad that consists of the consensus penta-peptide motif, GESAG. EstES1 demonstrated a broad substrate specificity toward the long acyl group of ethyl esters (C2-C12), and its optimal activity was recorded toward p-Nitrophenyl butyrate (C4) at pH 9.0 and $40^{\circ}C$ (specific activity of 255.4 U/mg). The enzyme remained stable in the ranges of $60-65^{\circ}C$ and pH 9.0-10.5 and in the presence of methanol, ethanol, isopropanol, and dimethyl sulfoxide. Therefore, EstES1 has potential for use in industrial applications involving high temperature, organic solvents, and/or alkaline conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.3
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• pp.348-356
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• 2008

For the effective use of rainbow trout, the seasoned and dried rainbow trout slice (SR) was prepared and its characterization was compared with the commercial skipjack tuna (CSS) and pork products (CSP) by determining chemical components and sensory evaluation. The moisture content of SR, 20.5%, was lower, and the lipid content of SR, 7.5%, was higher than those of commercial products, CSS and CSP. The protein content of SR (41.4%) was higher than that of CSS (28.6%), but lower than that of CSP (50.1%). The water activity of SR was 0.654, which was lower than those of CSS and CSP, 0.724 and 0.771, respectively. According to the results, the color of SR was lower in lightness and redness and higher in browning index and ${\Delta}$E value than that of commercial products. The texture of SR was harder than that of CSS, but softer than that of CSP. According to the result of taste value, the taste of SR was stronger than that of CSP, while weaker than that of CSS. The mineral (Ca, P, and Fe), total amino acid contents, and the n-3/n-6 of SR showed significant levels in nutrition and health functional senses.

• Microbiology and Biotechnology Letters
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• v.42 no.1
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• pp.58-66
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• 2014

In the course of study for a use for non-edible parts of broccoli (Brassica oleracea L), and the development of processed food utilizing these parts, edible floret and non-edible stalk were extracted with ethanol and different organic solvent fractions were prepared. With 10 different extracts and fractions, their useful components and various biological activities, such as antioxidant, antimicrobial and anti-proliferation activity, were investigated. The stalk has more abundant water soluble carbohydrate when compared with the floret, and floret has higher hexane-soluble pigments. Analysis of total flavonoid and total polyphenol contents showed that the floret has 1.5~1.99 times higher concentrations than the stalk. Among the fractions, ethylacetate (EA) fractions have the highest amount of total flavonoid and total polyphenol. The stalk and floret possessed 9.45 and 42.01 mg-total flavonoid/g, respectively. In the antioxidation activity assay, the EA fraction of floret showed strong radical scavenging activity and reducing power, while the n-hexane fraction of the stalk exhibited nitrite scavenging activity. In the antimicrobial activity assay, the EA fraction of floret showed a strong and broad-range of antibacterial activity, irrespective of gram positive or gram negative bacteria. In a while, the hexane and EA fractions revealed anti-proliferative effects against the human colorectal cancer cell HCT-116. Strong anti-proliferative activities were found in the hexane fraction of stalk (18.4% of cell viability), and the n-butanol fraction of floret (6.9% of cell viability). Our results suggest that the further study of the characterization of active fractions and the identification of active components from different parts of broccoli are needed to develop functional foods or novel plant-derived medicines.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.926-934
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• 2006

The base for preparing oyster hydrolysate-added yogurt was consisted of whole milk (1,000 mL), skim milk (44.05 to 42.05 g), enzymatic oyster hydrolysates powder (OHP, 0 to 2.0 g) and pectin. The yogurt base was fermented with 7 kinds of starter cultures (3% based on yogurt volume), such as Lactobacillus acidophilus, lactobacillus bulgaricus, lactobacillus casei, Lactobacillus fermentum, Lactobacillus pentosus, Streptcoccus thermophilus and the mixed starters (L. bulgaricus and S. thermophilus) at optimal temperature. Processing condition and quality characteristics of the yogurt were evaluated by analyzing pH, titratable acidity, viscosity, viable cell count, functional properties and sensory evaluation. The results suggested that the optimal conditions for preparing the good quality yogurt revealed the mixed starters (L. bulgaricus and S. thermophilus) for starter culture, 1.0 g of 3 kDa hydrolysate for amount, and 5.5 hrs for fermentation time. The good quality yogurt showed 4.31 for pH, 1.07% for titratable acidity, 469 cps for viscosity and $4.9{\times}10^8\;CFU/mL$ for viable cell count. The hydrolysate-added yogurt was 2 times higher in ACE inhibitory and antioxidant activities than commercial yogurt, and kept good quality during storage of 15 days at $5^{\circ}C$.

• Journal of Life Science
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• v.32 no.1
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• pp.1-10
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• 2022

Natural products have gained increasing attention due to their advantage of long-term safety and low toxicity for a very long time. Torreya nucifera is widespread in southern Korea and Jeju Island and its seeds are commonly used as edible food. Oriental ingredients have often been reported for their insecticidal, antioxidant and antibacterial properties, but there have not yet been any studies on their antidiabetic effect. In this study, we investigated several biological activities of T. nucifera pericarp (TNP) and seeds (TNS) extracts and proceeded to characterize the antidiabetic compounds of TNS. The initial results suggested that TNS extract at 15 and 10 ㎍/ml concentration has inhibitory effects on α-glucosidase and protein tyrosine phosphatase 1B, that is 14.5 and 4.35 times higher than TNP, respectively. Thus, the stronger antidiabetic TNS was selected for the subsequent experiments to characterize its active compounds. Ultrafiltration was used to determine the apparent molecular weight of the active compounds, showing 300 kDa or more. Finally the mixture was then partially purified using Diaion HP-20 column chromatography by eluting with 50~100% methanol. Therefore we concluded that the active compounds of TNS have potential as therapeutic agents in functional food or supplemental treatment to improve diabetic diseases.