• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6029-6038
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• 2013

In this study we attempt to modify the backbone structure and improve processibility of PBO having high melting and glass transition temperature. A series of aromatic poly(o-hydroxyamide)s(PHAs) were synthesized by direct polycondensaton of diacides containing diimide unit with two types of bis(o-aminophenol)s including 3,3'-dihydroxybenzidine and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. PHAs were studied by FT-IR, $^1H$-NMR, DSC and TGA. PHAs exhibited inherent viscosities in the range of 0.34~0.65 dL/g at $35^{\circ}C$ in DMAc solution. The PHA 1 and 6F-PHA 6, introducing o-phenylene unit in the main chain showed excellent solubilities in aprotic solvents such as NMP etc. However, the PHA 3, having p-phenylene unit was not even dissolved perfectly with LiCl salt. 6F-PHAs were readily soluble at room temperature in aprotic solvents except 6F-PHA 3. But they showed better solubility than that of PHAs. The polybenzoxazoles(PBOs) were quite insoluble in other solvents except partially soluble in sulfuric acid. PBOs exhibited relatively high glass transition temperatures(Tg) in the range of 306~$311^{\circ}C$ by DSC. The maximum weight loss temperature and char yields of PHA3 and 6F-PHA3 showed the highest values of $658^{\circ}C$ and $653^{\circ}C$, 62.6 % and 62.1 %, respectively.

• Polymer(Korea)
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• v.34 no.6
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• pp.495-500
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• 2010

Crosslinked PI films were synthesized from 4,4'-(hexafluoro isopropylidene)diphthalic anhydride (6FDA) and bis[4-(3-aminophenoxy) phenyl] sulfone(BAPS) with various ratios of the reactive monomer cis-4-cyclohexene-1,2-dicarboxylic anhydride(CDBA). We prepared crosslinked poly(amic acid) (PAA) using a 0.1 wt% Grubbs catalyst as a crosslinking agent. The crosslinked PAA was heat-treated at different temperatures to give PI films. The thermo-mechanical properties and optical transparency of the PI films were investigated. The thermal properties of the PI films were examined using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry(DSC), thermogravimetric analysis(TGA), thermo-mechanical analysis(TMA), and universal tensile machine(UTM), and their optical transparencies were investigated using UV-vis. spectrophotometry. The thermomechanical properties of the PI films improved with increasing CDBA content. However, the optical transparency of the PI films decreased slightly with increasing CDBA content.

• Macromolecular Research
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• v.14 no.1
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• pp.87-93
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• 2006

Copolymers composed of hyaluronic acid (HA) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to create temperature-sensitive injectable gels for use in controlled drug delivery applications. Semi-telechelic PNIPAAm, with amino groups at the end of each main chain, was synthesized by radical polymerization using 2-aminoethanethiol hydrochloride (AESH) as the chain transfer agent, and was then grafted onto the carboxyl groups of HA using carbodiimide chemistry. The result of the thermo-optical analysis revealed that the phase transition of the PNIPAAm-grafted HA solution occurred at around 30$\∼$33$^{circ}C$. As the graft yield of PNIPAAm onto the HA backbone increased, the HA-g-PNIPAAm copolymer solution exhibited sharper phase transition. The short chain PNIPAAm-grafted HA ($M_{w}$=6,100) showed a narrower temperature range for optical turbidity changes than the long chain PNIPAAm-grafted HA ($M_{w}$=13,100). PNIPAAm-grafted HA exhibited an increase in viscosity above 35$^{circ}C$, thus allowing the gels to maintain their shape for 24 h after in vivo administration. From the in vitro riboflavin release study, the HA-g-PNIPAAm gel showed a more sustained release behavior when the grafting yield of PNIPAAm onto the HA backbone was increased. In addition, BSA released from the PNIPAAm-g-HA gels showed a maximum concentration in the blood 12 h after being injected into the dorsal surface of a rabbit, followed by a sustained release profile after 60 h.

• Molecules and Cells
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• v.27 no.1
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• pp.47-54
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• 2009

A cDNA clone for a transcript preferentially expressed during an early phase of flooding was isolated from Nicotiana tabacum. Nucleotide sequencing of the cDNA clone identified an open reading frame that has high homology to the previously reported glycine-rich RNA-binding proteins. The open reading frame consists of 157 amino acids with an N-terminal RNA-recognition motif and a C-terminal glycine-rich domain, and thus the cDNA clone was designated as Nicotiana tabaccum glycine-rich RNA-binding protein-1 (NtGRP1). Expression of NtGRP1 was upregulated under flooding stress and also increased, but at much lower levels, under conditions of cold, drought, heat, high salt content, and abscisic acid treatment. RNA homopolymer-binding assay showed that NtGRP1 binds to all the RNA homopolymers tested with a higher affinity to poly r(G) and poly r(A) than to poly r(U) and poly r(C). Nucleic acid-binding assays showed that NtGRP1 binds to ssDNA, dsDNA, and mRNA. NtGRP1 suppressed expression of the fire luciferase gene in vitro, and the suppression of luciferase gene expression could be rescued by addition of oligonucleotides. Collectively, the data suggest NtGRP1 as a negative modulator of gene expression by binding to DNA or RNA in bulk that could be advantageous for plants in a stress condition like flooding.

• Journal of Plant Biology
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• v.39 no.1
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• pp.9-13
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• 1996

A clone, LCM1, which encodes calmodulin (CaM) was isolated and characterized from monocot lily (Lilium longiflorum Thunb.) plants. The clone is 681 bps and contains the 447 bp coding region, 8 bp leader sequence, 210 bp 3'-untraslated region, and a poly(A) tail. The coding region of 149 amino acids encodes a protein of predicted Mr 17 kD. Comparison of the LCM1 amino acid sequence with other CaMs revealed that the protein is highly conserved among various living organisms. The expression level of calmodulin gene in lily was studied by RNA blot analysis. The LCM1 mRNA was present in all tissues tested. However, a higher level of calmodulin was observed in anther and floral bud. The level of calmodulin mRNA in anther was about 10 times higher than that in anther was about 10 times higher than that in vegetative tissues. The anther preferential expression of CaM in lily is currently investigated in dicot plants.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.31-35
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• 1998

1. INTRODUCTION : Recognition and binding of organic substrates by biological molecules are of vital importance in biophysics and biophysical chemistry. Most studies of the application focused on the development of biosensors, which detected reaction products generated by the binding between enzymes and substrates. Other types of biosensors in which membrane proteins (e.g., nicotinic acetylcholine receptor, auxin receptor ATPase, maltose bining protein, and glutmate receptor) were utilized as a receptor function were also developed. In the previous study[1], the shifts in membrane potential, caused by the injection of substrates into a permeation cell, were measured using immobilized glucose oxidase membranes. It was suggested that the reaction product was not the origin of the potential shifts, but the changes in the charge density in the membrane due to the binding between the enzyme and the substrates generated the potential shifts. In this study, $\gamma$-globulin was immobilized (entrapped) in a poly($\gamma$-amino acid) network, and the shifts in the membrane potential caused by the injection of some amino acids were investigated.

• The Plant Pathology Journal
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• v.15 no.5
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• pp.270-279
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• 1999

cDNAs complementary to the 3'-terminal regions of two potyvirus genomes were cloned and sequenced. The clone G7 contains one open reading frame (ORF) of 1,338 nucleotides and a 3' untranslated region (3'-UTR) of 403 nucleotides at the 3'-end excluding the 3'end poly(A) tail. The putative viral coat protein (CP) shows 55%-92% amino acid sequence homology to those of Allium potyviruses. The genome size of the virus was analyzed to be about 9.0 kb by Northern blot analysis. Five cDNA clones were screened out using GPV2 oligonucleotide as a probe. One of these clones, DEA72, which has a longest cDNA insert, contains one ORF of 1,459 nucleotides and a 3'-UTR of 590 nucleotides at the 3'-end excluding the 3'-end poly(A) tail. The putative viral CP shows 57%-88% amino acid sequence homologies to those of Allium potyviruses. The genome size of the virus was analyzed to be about 9.6 kb by Northern blot analysis. The results of immunoblot and Northern blot analyses suggest that almost all of the tested garlic plants showing mosaic or streak symptoms are infected with DEA72-potyvirus in variable degrees but rarely infected with G7-potyvirus in variable degrees but rarely infected with DEA72-potyvirus in variable degrees but rarely infected with G7-potyvirus. Immunoelectron microscopy using anti-DEA72 CP antibody shows that this potyvirus is about 750 nm long and flexuous rod shaped.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1279-1284
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• 2008

When cheonggukjgang was manufactured using a Bacillus subtilis CH10-1 starter culture, a short-term fermentation for 14-18 hr appeared to be the optimal for the raw cheonggukjang to avoid the formation of a bitter taste and to contain a high concentration of free sugars, whereas a long-term fermentation for more than 4 days was the optimal for the cheonggukjang for stew in order to contain a high concentration of free amino and organic acids, which are responsible for sweet, savory, and bitter tastes present in stewed cheonggukjang, During activation of murine splenic T cells with phytohemagglutinin (PHA), the presence of either poly-$\gamma$-glutamic acid ($\gamma$-PGA) or partially hydrolyzed $\gamma$-PGA resulted in reduction in the level of interferon-$\gamma$ production and enhancement in the level of interleukin-5 production, possibly due to suppression of Th1 activity and augmentation of Th2 activity. Taken together these results indicate that the raw cheonggukjang and the cheonggukjang for stew are different in their quality and taste as well as immunomodulating activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.16 no.4
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• pp.306-310
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• 1987

These experiments were conducted to find out the possibility of utilizing apricot seed as resources of food protein. The apricot seed contained 23.3% of crude protein. The salt soluble protein of apricot seed was highly dispersible in 0.2M sodium phosphate buffer containing about 0.3M $MgSO_4$, and the extractability of seed protein was about 35%. Major amino acid composition of apricot protein were glutamic acid and aspartic acid. The electrophoretic analysis showed 9 bands in apricot seed protein. Molecular weight for the main protein of the apricot seed separated by 1% SDS polyacrylamide gel electrophoresis was 49,000. Molecular weights of salt soluble protein measured by Sephadex G-200 was 110,000.

• The Plant Pathology Journal
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• v.34 no.5
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• pp.451-457
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• 2018

The Sweet potato chlorotic fleck virus (SPCFV), of the genus Carlavirus (family Betaflexiviridae), was first detected as one of several viruses infecting sweet potatoes (Ipomea batatas L.) in Korea. Out of 154 sweet potato samples collected in 2012 that were showing virus-like symptoms, 47 (31%) were infected with SPCFV, along with other viruses. The complete genome sequences of four SPCFV isolates were determined and analyzed using previously reported genome sequences. The complete genomes were found to contain 9,104-9,108 nucleotides, excluding the poly-A tail, containing six putative open reading frames (ORFs). Further, the SPCFV Korean isolates were divided into two groups (Group I and Group II) by phylogenetic analysis based on the complete nucleotide sequences; Group I and Group II had low nucleotide sequence identities of about 73%. For the first time, we determined the complete genome sequence for the Group II SPCFV isolates. The amino acid sequence identity in coat proteins (CP) between the two groups was over 90%, whereas the amino acid sequence identity in other proteins was less than 80%. In addition, SPCFV Korean isolates had a low amino acid sequence identity (61% CPs and 47% in the nucleotide-binding protein [NaBp] region) to that of Melon yellowing-associated virus (MYaV), a typical Carlavirus.