• Food Science of Animal Resources
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• v.39 no.2
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• pp.296-308
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• 2019

Although the yellow mealworm (Tenebrio molitor L.) is a promising alternative protein source, the effects of processing conditions on functional properties are unclear. In this study, a protein extract of yellow mealworm larvae (PEYM) was subjected to different heat temperature ($55^{\circ}C$, $75^{\circ}C$, and $95^{\circ}C$) with different time (20, 40, and 60 min) to evaluate the functional properties and protein oxidation. Different heat temperature treatment significantly affected the exposure of surface hydrophobicity of the proteins and protein molecule aggregation, which reached maximum levels at $95^{\circ}C$ for 60 min. Protein oxidation was inversely proportional to the temperature. Both the highest carbonyl value (1.49 nmol/mg protein) and lowest thiol value (22.94 nmol/mg protein) were observed at $95^{\circ}C$ for 60 min. The heating time-temperature interaction affected several functional properties, including solubility, emulsifying potential, and gel strength (GS). Solubility decreased near the isoelectric point (pH 5 to 6). As the temperature and heating time increased, emulsifying properties decreased and GS increased. The oil absorption capacity and foaming properties decreased and the water absorption capacity increased. These results confirmed that PEYM is a suitable source of proteins for processing and applications in the food industry.

• BMB Reports
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• v.53 no.5
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• pp.260-265
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• 2020

Scorpion venom comprises a cocktail of toxins that have proven to be useful molecular tools for studying the pharmacological properties of membrane ion channels. HelaTx1, a short peptide neurotoxin isolated recently from the venom of the scorpion Heterometrus laoticus, is a 25 amino acid peptide with two disulfide bonds that shares low sequence homology with other scorpion toxins. HelaTx1 effectively decreases the amplitude of the K⁺ currents of voltage-gated Kv1.1 and Kv1.6 channels expressed in Xenopus oocytes, and was identified as the first toxin member of the κ-KTx5 subfamily, based on a sequence comparison and phylogenetic analysis. In the present study, we report the NMR solution structure of HelaTx1, and the major interaction points for its binding to voltage-gated Kv1.1 channels. The NMR results indicate that HelaTx1 adopts a helix-loop-helix fold linked by two disulfide bonds without any β-sheets, resembling the molecular folding of other cysteine-stabilized helix-loop-helix (Cs α/α) scorpion toxins such as κ-hefutoxin, HeTx, and OmTx, as well as conotoxin pl14a. A series of alanine-scanning analogs revealed a broad surface on the toxin molecule largely comprising positively-charged residues that is crucial for interaction with voltage-gated Kv1.1 channels. Interestingly, the functional dyad, a key molecular determinant for activity against voltage-gated potassium channels in other toxins, is not present in HelaTx1.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.25-34
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• 2002

Background: Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial hyperplasia and joint destruction. The synovial fibroblasts express cell adhesion molecules and have a role in adhesive interation with inflammatory cells in synovial tissue. It has been suggested that hypoxic conditioins are thought to exist in arthritic joints, and several studies indicate that reactive oxygen species (ROS) produced in hypoxic condition can initiate events that lead to pro-adhesive changes via increased expression of adhesion molecules. So, this study wsa designed to examine whether antioxidant can inhibit hypoxia-induced expression of ICAM-1 in cultured human synovial fibroblasts. Methods: Synovial fibroblasts were isolated from synovial tissue in patients with RA and cultured at hypoxic condition. Antioxidant, PDTC (pyrrolidine dithiocarbamate) were pre-treated for an hour before the hypoxic culture and synovial fibroblasts were harvested at 0, 6, 12, 24, 48 hours time points. Cell surface ICAM-1 expression in synovial fibroblasts was examined by the flow cytometric analysis. To analyse the expression of ICAM-1 mRNA, reverse-transcriptase polymerase chain reaction (RT-PCR) was performed. The levels of cytokines in culture supernatants were measured by ELISA, and activation of NF-${\kappa}B$ was analysed by electrophoretic mobility shift assay. The adhesive reaction between synovial fibroblasts and lymphocytes was assayed by measurement of fluorescent intensity of BCECF-AM in lymphocytes. Results: Hypoxic stimuli up-regulated the ICAM-1 expression as well as the adhesive interaction of human synvial fibroblasts to lymphocytes in a time-dependent manner, and PDTC inhibited hpyoxia-induced ICAM-1 expression and cell-cell interaction. PDTC also inhibited the hypoxia-induced activation of intracellular transcription factor, NF-${\kappa}B$. PDTC decreased the amount of hypoxia-induced production of IL-$1{\beta}$ and TNF-${\alpha}$. Conclusion: These studies demonstrate that PDTC inhibit the hypoxia-induced expression of the adhesion molecule, ICAM-1 and activation of NF-${\kappa}B$ in cultured human synovial fibroblasts.

• Journal of the Korean Vacuum Society
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• v.13 no.4
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• pp.157-163
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• 2004

Dependence of residual compressive stress of diamond-like carbon (DLC) films on relative humidity was investigated. Polymeric, graphitic and diamond-like carbon films were prepared by r.f.-PACVD using methane or benzene with the negative self bias voltage of the substrate ranging from -100 to -800 V. In-situ measurements of the residual stress were carried out in an environment chamber where the relative humidity was varied from 10％ to 90％. In dense DLC film of high residual compressive stress and hardness, we could not observe any change in the residual compressive stress with relative humidity. However, in the cases of graphitic and polymeric DLC films, abrupt change in the residual stress occurred by changing the relative humidity. The quantity of the stress change was inversely proportional to the film thickness, which means that the stress change with humidity is not due to the penetration of the water molecule into the film structure, but due to surface interaction between water molecules and film surface.

• KSBB Journal
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• v.21 no.4
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• pp.279-285
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• 2006

We investigated the effects of immobilization chemistry on the yield of immobilization and the bioactivity of the immobilized enzymes. Trypsin as a model protein and macroporous polymer beads(Toyopearl AF 650M, Tosho Co., Japan) was used as a model matrix. Four methods were used to immobilize trypsin; covalent conjugation by reductive amination(at pH 10.0 and pH 4.0) and affinity interaction via streptavidin-biotin, and double-affinity interaction via biotin-streptavidin-biotin system. The covalent conjugation immobilized $3{\sim}4$ mg/ml-gel, ca. 3-fold higher than the affinity method. However, the specific activity of the covalently(pH 10.0) and affinity-immobilized trypsin(via streptavidin-biotin) are ca. 37% and 50%, respectively, of that of the soluble enzyme(on the low-molecular-weight BAPNA substrate). When the molecular size of a substrate increased, the affinity-immobilized trypsin showed higher clavage activity on insulin and BSA. This result seemed to indicate the streptavidin-biotin system allowed more steric flexibility of the immobilized trypsin in its interaction with a substrate molecule. To confirm this, we studied the molecular flexibility of immobilized trypsin using quartz crystal microbalance-dissipation. Self-assembled monolayers were formed on the Q-sensor surface by aminoalkanethiols, and gultaraldehyde was attached to the SAMs. Trypsin was immobilized in two ways: reductive amination(at pH 10.0) and the streptavidin-biotin system. The dissipation shift of the affinity-immobilized trypsin was $0.8{\times}10^{-6}$, whereas that of the covalently attached enzyme was almost zero. This result confirmed that the streptavidin-biotin system allowed higher molecular flexibility. These results suggested that the bioactivity of the immobilized enzyme be strongly dependent on its molecular flexibility.

• Journal of the Korean Chemical Society
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• v.37 no.3
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• pp.294-301
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• 1993

${\pi}$-A isotherms of the Palmitic acid(PA) with increasing pH shifted to the low area/molecule due to the dissociation of PA at the air-water interface. More condensation of PA monolayers occurred by the addition of Mg$^{2+}$, Ca$^{2+}$ and Ba$^{2+}$ ion in subphase. This condensing effect was increased with increasing the concentration of these ions. Due to the interaction with each ion, PA were formed Mg, Ca, Ba-Palmitate complex. The binding structure between alkaline earth ion and carboxylate ligand in PA has been identified by IR spectrometry. The order of condensing effect of alkaline earth ions at pH 8 was Ca$^{2+}$ > Ba$^{2+}$+ > Mg$^{2+}$. The condensing effect except for Mg$^{2+}$ decreased with increasing atomic number. Whereas, the condensing effect in pure water system decreased with decreasing atomic number in the sequence: Ba$^{2+}$ > Ca$^{2+}$ > Mg$^{2+}$. The miscibility of binary system of PA and hexadecanol in monolayer showed that the miscibility was good for the pure water system. But, in the buffered pH 8 system, bad miscibility was found.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.546-546
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• 2008

Copper (Cu) Chemical mechanical polishing (CMP) has been an essential process for Cu wifing of DRAM and NAND flash memory beyond 45nm. Copper has been employed as ideal material for interconnect and metal line due to the low resistivity and high resistant to electro-migration. Damascene process is currently used in conjunction with CMP in the fabrication of multi-level copper interconnects for advanced logic and memory devices. Cu CMP involves removal of material by the combination of chemical and mechanical action. Chemicals in slurry aid in material removal by modifying the surface film while abrasion between the particles, pad, and the modified film facilitates mechanical removal. In our research, we emphasized on the role of chemical effect of slurry on Cu CMP, especially on the effect of amine functional group on removal rate selectivity between Cu and Tantalum-nitride (TaN) film. We investigated the two different kinds of complexing agent both with amine functional group. On the one hand, Polyacrylamide as a polymer affected the stability of abrasive, viscosity of slurry and the corrosion current of copper film especially at high concentration. At higher concentration, the aggregation of abrasive particles was suppressed by the steric effect of PAM, thus showed higher fraction of small particle distribution. It also showed a fluctuation behavior of the viscosity of slurry at high shear rate due to transformation of polymer chain. Also, because of forming thick passivation layer on the surface of Cu film, the diffusion of oxidant to the Cu surface was inhibited; therefore, the corrosion current with 0.7wt% PAM was smaller than that without PAM. the polishing rate of Cu film slightly increased up to 0.3wt%, then decreased with increasing of PAM concentration. On the contrary, the polishing rate of TaN film was strongly suppressed and saturated with increasing of PAM concentration at 0.3wt%. We also studied the electrostatic interaction between abrasive particle and Cu/TaN film with different PAM concentration. On the other hand, amino-methyl-propanol (AMP) as a single molecule does not affect the stability, rheological and corrosion behavior of the slurry as the polymer PAM. The polishing behavior of TaN film and selectivity with AMP appeared the similar trend to the slurry with PAM. The polishing behavior of Cu film with AMP, however, was quite different with that of PAM. We assume this difference was originated from different compactness of surface passivation layer on the Cu film under the same concentration due to the different molecular weight of PAM and AMP.

• Journal of the Korean Chemical Society
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• v.31 no.4
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• pp.295-300
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• 1987

Spectroscopic studies have been carried out on the metachromatic behavior of methylene blue(MB) and acridine orange(AO) in the presence of chondroitin sulfate A(CSA) and chondroitin sulfate C(CSC). The characteristic changes of the meta-band with the changes of P/D value are discussed in terms of the stacking theory. Quantitative studies on the stacking effect are made to calculate the number of bound molecules of dye per unit molecule of the polyanion. The result shows that MB has stronger stacking effect than AO. A stacking model and the dimension of the bound dyes on the surface of the polyanion are proposed, on the basis of the dimer model of planar aromatic dyes and the most stable conformation of the CSA chain. The model is found to be reasonable in accordance with the experimental results.

• YAKHAK HOEJI
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• v.51 no.6
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• pp.482-489
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• 2007

Kaempferitrin, isolated from Kenaf (Hibiscus cannabinus), was examined to evaluate its modulatory effects on antigen-presenting cell functions of macrophages/monocytes such as phagocytosis of foreign materials, up-regulation of costimulatory molecules (CD40, CD80 and CD86), adhesion molecule activation, and antigen processing and presentation. Kaempferitrin strongly blocked up-regulation of CD40, CD80 and CD86, but not pattern recognition receptor (PRR) (e.g., TLR2). It also suppressed functional activation of CD29 (${\beta}1$-integrins), as assessed by cell-cell adhesion assay, required for T cell-antigen-presenting cell (APC) interaction. Furthermore, this compound did not block a simple activation of CD29, as assessed by cell-fibronectin adhesion assay. However, the compound did not diminish phagocytic uptake, an initial step for antigen processing, and ROS generation in RAW264.7 cells. In particular, to understand molecular mechanism of kaempferitrin-mediated inhibition, the regulatory role of LPS-induced signaling events was examined using immunoblotting analysis. Interestingly, this compound dose dependently suppressed the phosphorylation of $I{\kappa}B{\alpha}$, Src, Akt and Syk, demonstrating that it can negatively modulate the activation of these signaling enzymes. Therefore, our data suggested that kaempferitrin may be involved in regulating APC function-relevant immune responses of macrophages and monocytes by regulating intracellular signaling.

• KSBB Journal
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• v.24 no.3
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• pp.227-238
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• 2009

In the recent years, some organic toxic chemicals were used for obtaining high-yield productivity in agriculture. The undegraded pesticides may remain in the agricultural foods through atmosphere, water, and soil and cause public health problems to environmental resources and human beings even at very low concentrations. Small amounts of pesticides can affect a central nervous system, resulting in immunogenic diseases, infertility problems, respiratory diseases and born marrow diseases, which can lead even to death. Monitoring of the environmental pesticide is one of the important issues for the human well-being. Several kinds of biosensors have been successfully applied to the detection of agrichemical toxicity. Also, few platforms for biocide detection have been definitely developed for the degradation and reaction of pesticides. Biochip and electrochemistry experiments involve immobilizing a receptor molecule on a solid substrate surface, and monitoring its interaction with an analyze in a sample solution. Furthermore, nanotechnology can be applied to make high-throughput analyses that are smaller, faster and sensitive than conventional assays. Some nanomaterials or nanofabricated surfaces can be coupled to biomolecules and used in antibody-based assays and enzymatic methods for pesticide residues. The operation procedure has become more convenient as it does not require labeling procedure. In this paper, we review the recent advances in agrichemical defection research and also describe the label-free biosensor for pesticides using various useful detection methods.