• KSBB Journal
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• v.19 no.2
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• pp.164-167
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• 2004

Cyclodextrin glucanotransferase (EC 2.4.1.19, abbreviated as CGTase) is one of the most applied industrial enzymes that produces cyclodextrins from starch and related ${\alpha}$-1,4-glucans by intramolecular transglycosylation reaction upon Ca$\^$2＋/ dependent manner. The reaction of CLEC, ${\alpha}$-CGTases from Bacillus macerans with the soluble starch as a substrate reveals that the surfactants (SDS, N-octyl-${\beta}$-D-glucoside) significantly affect not only the overall products of CDs but also their selectivity. The surfactants (SDS, Lubrol PX) trigger the increase of ${\alpha}$-CD production, but Triton x-100 and Tween 80 suppress ${\alpha}$-CD specificity. Organic solvents (dimethyl sulfoxide, formamide, 2-methyl-2,4-pentandiol, and ethylene glycol) also cause changes of total product and product selectivity.

• Journal of Environmental Health Sciences
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• v.36 no.3
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• pp.236-246
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• 2010

In preparative anti-corrosive coating experiments, polyaniline was obtained by reacting an oxidizing agent with the monomer aniline. Further, the primer coating was prepared using a variety of widely-used materials such as urethane resin. For the top coating, epoxy resin and acrylic urethane resin were used. Characteristics of the coatings were assessed according to KS and ASTM specifications, and the structure of the polyaniline was characterized using FT-IR and TGA. For analysis of anti-corrosive properties in salt-spray experiments, measurements of the oxidation state of iron and surface atomic analysis were conducted using XPS and SEM-EDX. Unlike general anti-corrosive coatings which exhibit anti-corrosive effects only as a primer coating, the anti-corrosive coatings using polyaniline as the anti-corrosive pigment showed a marked synergistic effect with the top coatings. In other words, the top coatings not only produce a fine view effect, but also increase, through interaction with the primer coatings, the resistance to diffusion of corrosive factors from the external environment. It was also found that, unlike the heavy metal oxide-forming layer of the passive barrier alone, the polyaniline anti-corrosive pigment oxidized iron at the interface with the iron substrate to form a passive barrier in the oxidic layer, and itself formed a potential barrier layer with anti-corrosive factors from the external environment. Although the passive layer was damaged, the damaged area did not become completely oxidized iron; on the contrary, it showed a tendency to reduction. This can be interpreted such that a passive layer is formed again on the damaged area, and that at the same time there is a tendency to self-healing.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.468-471
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• 2015

Microalgae have the advantages of being able to utilize the solar energy and culturing at a low cost. In particular, microalgae have a great potential in the production of biodiesel due to the high lipid content. Lipids produced from microalgae are converted to fatty acid methyl ester (FAME) by trans-esterification reaction and FAME is called a biodiesel in general. In addition, microalgae can also be utilized as a substrate for ethanol fermentation after saccharification reaction. In this study, three types of microalgae (Nanochloris, Dunaliella tertiolecta, Tetraselmis) were cultured and their lipid contents were compared. In addition, the effects of lighting period on the growth rate and lipid content were studied. Finally, the amounts of glucose produced from each saccharified microalgae were investigated. As a result, we demonstrated that D. tertiolecta has 43.6% higher lipid content and 22% higher glucose conversion than two others.

• Biomedical Science Letters
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• v.15 no.1
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• pp.55-60
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• 2009

Insect cells such as Spodoptera frugiperda Clone 9 (Sf9) cells are widely chosen as the host for heterologous expression of a mammalian sugar transport protein using the baculovirus expression system. Characterization of the expressed protein is expected to include assay of its function, including its ability to transport sugars and to bind inhibitory ligands such as cytochalasin B. It is therefore very important first to establish the transport characteristics and other properties of the endogenous sugar transport proteins of the host insect cells. However, very little is known of the transport characteristics of Sf9 cells, although their ability to grow on TC-100 medium strongly suggested the presence of endogenous glucose transport system. In order to investigate the substrate and inhibitor recognition properties of the Sf9 cell transporter, the ability of pentoses to inhibit 2-deoxy-D-glucose (2dGlc) transport was investigated by measuring inhibition constants $(K_i)$. To determine the time period over which of sugar into the Sf cells was linear, the uptake of 2dGlc 0.1mM extracellular concentration was measured over periods ranging from 30 seconds to 30 minutes. The uptake was linear for at least 2 minutes at the concentration, implying that uptake made over a 1 minute time course would reflect initial rates of the sugar uptake. The data have also revealed the existence of a saturable transport system for pentose uptake by the insect cells. The transport was inhibited by D-xylose and D-ribose, although not as effective as hexoses. However, L-xylose had a little effect on 2dGlc transport in the Sf9 cells, indicating that the transport is stereoselective. Unlike the human erythrocyte-type glucose transport system, D-ribose had a somewhat greater apparent affinity for the Sf9 cell transporter than D-xylose. It is therefore concluded that Sf9 cells contain an endogenous sugar transport activity that in some aspects resembled the human erythrocyte-type counterpart, although the Sf9 and human transport systems do differ in their affinity for cytochalasin B.

• BMB Reports
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• v.29 no.6
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• pp.500-506
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• 1996

We have isolated a water-extracted novel regulator for blood coagulation from an earthworm, Lumbricus rubellus. As a folk remedy, the earthworm has been known to facilitate blood circulation. After complete heat inactivation of endogenous proteases in the earthworm, an anticoagulant(s) was purified through ammonium sulfate fractionation and three consecutive gel permeation chromatography of Sephacryl S-300, Sephadex G-75, and G-150 by measuring activated partial thromboplastin time (APTT) The anticoagulant was further purified to 2,800 fold with a C4 reversed-phase HPLC This activity was stable under heat ($100^{\circ}C$ for 30 min) and acidic conditions (0.4 N HCl). The effects of this partially purified anticoagulant on thrombin were observed with various substrates such as N${\alpha}$-benzoyl-DL-arginine-p-nitroanilide (BApNA), H-D-phenylalanyl-L-pipecoyl-L-arginine-p-nitroanilide (S-2238), N${\alpha}$-p-tosyl-L-arginine methyl ester (TAME), and fibrinogen as a natural substrate. Only TAME hydrolysis, due to an esterase activity of the enzyme, was inhibited among the chromogenic substrates. In addition, the anticoagulant not only inhibited the conversion of fibrinogen to fibrin but also prolonged the fibrin clot formation monitored with the in vitro coagulation test. Based on these observations, we suggest the significance of measuring the ability of antithrombotic drugs to inhibit the esterase activity of thrombin. In this report, it was also shown that the earthworm indeed contained a water-extractable, heat- and acid-stable anticoagulant which could be used as a novel antithrombotic agent.

• Journal of Ginseng Research
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• v.19 no.3
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• pp.212-218
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• 1995

A human hepatoma cell line, hep G2, was used to investigate the mechanism of serum cholesterol reduction by ginseng total saponin, ginsenoside-$Rb_1$, - $Rb_2$, and non-saponin fraction (ether extraction). Hep G2 cells were incubated in 10 $\mu\textrm{g}$/ml of cholesterol containing serum free-RPMl1640 medium with various concentration of ginseng components. The amounts of cholesterol in Hep G2 cells were decreased to maximum 51% in total saponin or two ginsenoside-treated groups while there was 137% increase in cholesterol level of control group as compared with that of normal group. Nonsaponin groups did not show the same effect. In order to elucidate the observed changes in the amount of cholesterol, the activity of amyl CoA : cholesterol acyltransferase (ACAT) in groups showing remarkable reduction in cholesterol amount, i.e., total saponin 10-6%, ginsenoside-$Rb_1$ $10^{-4}$%, ginsenoside-$Rb_2$, $10^{-4}$%, and non-saponin fraction $10^{-4}$%, was assayed using [1-$^{-14}C$%]oleic acid as enzyme substrate. The activity of ACAT was increased in all groups tested as compared with that of control group except for non-saponin group cultured in water soluble cholesterol containing medium. The serum cholesterol lowering effects of ginseng components can partially be attributed to the increased hepatocellular ACAT activity.

• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.137-143
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• 2020

This study examined the effects of rapid thermal annealing (RTA) on the physical and chemical characteristics of thin silver (Ag) layers on SiO2 coated metal foils. Ag layers were annealed at various temperatures of the range between 150 ℃ and 550 ℃ for 20 min. The surface roughness and resistivity are increased at the annealing temperatures of 550 ℃. We also found that oxygen (O) and silicon (Si) atoms exist at the Ag film surface by using compositional analysis in the annealing temperatures of 550 ℃. The total reflectance is decreased with increasing temperature. These phenomena are due to an out-diffusion of Si atoms from SiO2 layers during the RTA annealing. The results offer the possibility of using it as a substrate for various flexible optoelectronic devices.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1972-1978
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• 2012

The polymer of (2,2-dimethyl-1,3-propanediaminebis(salicylideneaminato))-nickel(II), Ni(saldMp), was deposited on multi-walled carbon nanotubes (MWCNTs) substrate by the route of potential linear sweep. The nano structures of poly[Ni(saldMp)] have been obtained by adjusting the monomer concentration of 0.1, 0.2, 0.5, 1.0 and 1.5 mmol $L^{-1}$. The poly[Ni(saldMp)] prepared in acetonitrile solution with monomer concentration of 1.0 mmol $L^{-1}$ shows the fastest growth rate. The effects of potential window on charge-discharge efficiency and electrodeposition scan number on capacitance performance were discussed. Poly[Ni(saldMp)] prepared with less electrodeposition scans exhibits higher capacitance, but this goes against the improvement of the whole electrode capacitance. Sample with 8 deposition scans is the best compromise with the geometric specific capacitance 3.53 times as high as that of pure MWCNTs, and 1.24 times for the gravimetric specific capacitance under the test potential window 0.0-1.0 V.

• Journal of the Korean Chemical Society
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• v.57 no.6
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• pp.703-711
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• 2013

In the present investigation, kinetic studies of oxidation of formic acid with and without catalyst and promoter in aqueous acid media were studied under the pseudo-first order conditions [formic acid]T ${\gg}[Cr(VI)]_T$ at room temperature. In the 1,10-phenanthroline (phen) promoted path, the cationic Cr(VI) phen complex is the main active oxidant species undergoes a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition through several steps leading to the products $CO_2$ and $H_2$ along with the Cr(III) phen complex. The anionic surfactant (i.e., sodium dodecyl sulfate, SDS) and neutral surfactant (i.e., Triton X-100, TX-100) act as catalyst and the reaction undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Whereas the cationic surfactant (i.e., N-cetyl pyridinium chloride, CPC) acts as an inhibitor restricts the reaction to aqueous phase. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. The neutral surfactant TX-100 has been observed as the suitable micellar catalyst for the phen promoted chromic acid oxidation of formic acid.

• Korean Journal of Agricultural Science
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• v.47 no.3
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• pp.497-508
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• 2020

In this study, we investigated the protective effects of 'Donganme' (Sorghum bicolor L. Moench) against oxidative stress under in vitro conditions and in a cellular system using C6 glial cells. The radical scavenging activities were observed using the substrates 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl (•OH) radicals. The Donganme extract had an •OH radical scavenging activity of 82.66% at a concentration of 100 ㎍·mL^-1. Additionally, when DPPH was used as the substrate, the Donganme extract exhibited a strong radical scavenging activity in a concentration-dependent manner with an IC₅₀ value of 28.56 ㎍·mL^-1. Furthermore, treating C6 glial cells with hydrogen peroxide (H₂O₂) reduced the cell viability and generated reactive of oxygen species (ROS) and lactate dehydrogenase (LDH) compared to the normal levels, indicating that H₂O₂ induced oxidative stress. However, Donganme extracts increased the cell viability and inhibited ROS and LDH production against oxidative stress by H₂O₂ in the C6 glial cells. In particular, it showed effective cell protection with the cell viability, ROS production, and LDH release at 83.50, 88.06, and 14.87%, respectively, which were lower than the control or similar to the normal levels even at a low concentration of 100 ㎍·mL^-1. The present study suggests that the Donganme extract was effective in protecting against oxidative stress in C6 glial cells through its antioxidant activity. Thus, Donganme could be a promising therapeutic agent for neurodegenerative diseases due to oxidative stress.