• Clean Technology
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• v.20 no.2
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• pp.103-107
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• 2014

Acrylic acid is a commodity chemical which is applicable for various industries such as polymer and textile industry. Currently, it has been produced by chemical synthesis from petroleum. However, due to the high price of petroleum and global $CO_2$ emission, renewable materials such as sugar are interesting alternative carbon sources for the biological production of acrylic acid. For an economic production of acrylic acid from renewable carbon sources, a cost effective separation process for acrylic acid should be needed. In this study, reactive extraction by TOA (tri-n-octylamine) was used for the recovery of acrylic acid from its aqueous solutions. The effects of polarity of diluents and concentration of TOA on extraction equilibrium were investigated. The extraction efficiency was proportional to concentration of TOA and polarity of diluents and its value was more than 95% in the case of sufficient concentration of TOA. From IR spectroscopy, it was concluded that the ratio of (1,1) acid-amine complex was increased and the ratio of acid dimer was decreased with concentration of TOA. Equilibrium model based on IR spectroscopy was well fitted with experimental data.

• Polymer(Korea)
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• v.29 no.6
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• pp.599-604
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• 2005

The hyaluronic acid (HA) with excellent biocompatibility has been combined with lactide, the ester dimer of polylactide, with good biodegradability to produce biocompatible materials which can control the period of degradation in a human body. By freeze frying method, HA and lactide were crosslinked with crosslinking agent, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC). Degree of lactide and EDC reaction was determined by the analysis of nuclear magnetic resonance spectroscopy. Both lactyl group and EDC conversion increased as the mole ratio of lactide to HA increased from 5 to 13. The membrane swelled less and became more brittle with the more addition of lactyl group resulting from the higher mole ratio of lactide to HA. Swelling ratio decreased and tensile modulus increased due to the more addition of lactyl group as the EDC concentration increased or reaction temperature decreased. Drug release experiment from various membranes with different degree of crosslinking showed that permeability decreased with increasing degree of crosslinking. The degradation became slower with the more addition of lactyl group. Mechanical property and degradation rate of the synthesized membrane were shown to be controlled through adjusting operation parameters such as mole ratio, temperature, and crosslinking agent concentration.

• Genomics & Informatics
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• v.13 no.1
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• pp.15-24
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• 2015

Fatty acid synthase (FASN, EC 2.3.1.85), is a multi-enzyme dimer complex that plays a critical role in lipogenesis. This lipogenic enzyme has gained importance beyond its physiological role due to its implications in several clinical conditions-cancers, obesity, and diabetes. This has made FASN an attractive pharmacological target. Here, we have attempted to predict the theoretical models for the human enoyl reductase (ER) and ${\beta}$-ketoacyl reductase (KR) domains based on the porcine FASN crystal structure, which was the structurally closest template available at the time of this study. Comparative modeling methods were used for studying the structure-function relationships. Different validation studies revealed the predicted structures to be highly plausible. The respective substrates of ER and KR domains-namely, trans-butenoyl and ${\beta}$-ketobutyryl-were computationally docked into active sites using Glide in order to understand the probable binding mode. The molecular dynamics simulations of the apo and holo states of ER and KR showed stable backbone root mean square deviation trajectories with minimal deviation. Ramachandran plot analysis showed 96.0% of residues in the most favorable region for ER and 90.3% for the KR domain, respectively. Thus, the predicted models yielded significant insights into the substrate binding modes of the ER and KR catalytic domains and will aid in identifying novel chemical inhibitors of human FASN that target these domains.

• Natural Product Sciences
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• v.22 no.4
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• pp.299-306
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• 2016

This study aimed to establish the quantitative method to analyze the content of peroxynitrite-scavengers belonging to polyphenols in six Korean Quercus species (Quercus mongolica, Q. dentata, Q. acutissima, Q. alienta, Q. serrata, and Q. variabilis) by HPLC. The twelve peroxynitrite-scavengers, flavanols (catechins: (+)-catechin, (-)-epicatechin, and (-)-epigallocatechin), flavonols (kaempferol and quercetin), flavonol glycosides (astragalin, quercitrin, and isoquercitrin), flavonol acylated glycosides (astragalin 6''-gallate and isoquercitrin 6''-gallate), gallic acid and its dimer (ellagic acid) were analyzed by HPLC. Further, anti-Alzheimer's activity was assayed in a passive avoidance testusing mice by measuring the retention latency (sec), the concentration of acetylcholine (ACh), and acetylcholinesterase (AChE) activity. Simultaneous analysis of the extracts of the six Quercus leaves was achieved on a Capcell C18 column ($5{\mu}m$, $250mm{\times}4.6mm\;i.d.$) with a gradient elution of 0.05% HAc and 0.05% HAc in $CH_3CN$. In the extract of Q. mongolica leaves, the content of gallic acid (32.53 mg/g), (+)-catechin (28.78 mg/g), (-)-epicatehin (22.03 mg/g), astragalin 6''-gallate (20.94 mg/g), and isoquercitrin 6''-gallate (44.11 mg/g) and peroxynitrite-scavenging activity ($IC_{50}$, $0.831{\mu}g/ml$) were high. This extract delayed the retention latency and inhibited acetylcholinesterase activity in scopolamine-induced memory impairment of mice, suggesting that it has anti-Alzheimer's activity.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.531-542
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• 2012

The thesis covers the trend of research on bio-based polyurethane which is made from polyols derived mainly from plant oils and isocyanates. Castor oil is a triglyceride of ricinoleic acid containing hydroxyl group. Hydroxylation is done on the unsaturated bonds of the oils by the reactions of epoxidation/ring opening, hydroformylation/hydrogenation, ozonolysis/hydrogenation, and thiol-ene reaction. Polyols from hyperbranch, primary alcohol, polysaccharide have been studied to control the reactivity of the polyol and morphology of the microdomains. Besides, researches cover biodegradable polylactic acid polyol for medical use, fatty acid dimer polyol for the prevention of hydrolysis, and polyol with ionic group for water-borne polyurethane. Bio-based polyurethanes are being used in flexible and rigid foams, coatings, sealants, and elastomers.

• Membrane Journal
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• v.15 no.4
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• pp.281-288
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• 2005

The hyaluronic acid (HA) with excellent biocompatibility can be combined with lactide, the ester dimer of polylactide, with good biodegradability to produce biocompatible materials applicable to drug delivery system. By freeze drying method, HA and lactide were crosslinked with crosslinking agent, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide. Degree of lactide and EDC reaction was determined by the analysis of nuclear magnetic resonance (NMR) spectroscopy. The degree of lactide and EDC reaction increased and swelling ratio decreased as the mole ratio of lactide to HA or crosslinking agent concentration increased or reaction temperature decreased. The drug release experiment result from membranes having different degree of lactide reaction showed that drug release rate reduced in proportion to the degree of lactide reaction. The drug release experiment result from drugs having different hyrodphobicity showed that the more hydrophobic drug was released more slowly.

• Journal of Microbiology
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• v.45 no.4
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• pp.318-325
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• 2007

Glucose 6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) in Deinococcus radiophilus, an extraordinarily UV-resistant bacterium, was investigated to gain insight into its resistance as it was shown to be involved in a scavenging system of superoxide $(O_2^{-1})$ and peroxide $(O_2^{-2})$ generated by UV and oxidative stresses. D. radiophilus possesses two G6PDH isoforms: G6PDH-1 and G6PDH-2, both showing dual coenzyme specificity for NAD and NADP. Both enzymes were detected throughout the growth phase; however, the substantial increase in G6PDH-1 observed at stationary phase or as the results of external oxidative stress indicates that this enzyme is inducible under stressful environmental conditions. The G6PDH-1 and G6PDH-2 were purified 122- and 44-fold (using NADP as cofactor), respectively. The purified G6PDH-1 and G6PDH-2 had the specific activity of 2,890 and 1,033 U/mg protein (using NADP as cofactor) and 3,078 and 1,076 U/mg protein (using NAD as cofactor), respectively. The isoforms also evidenced distinct structures; G6PDH-1 was a tetramer of 35 kDa subunits, whereas G6PDH-2 was a dimer of 60kDa subunits. The pIs of G6PDH-1 and G6PDH-2 were 6.4 and 5.7, respectively. Both G6PDH-1 and G6PDH-2 were inhibited by both ATP and oleic acid, but G6PDH-1 was found to be more susceptible to oleic acid than G6PDH-2. The profound inhibition of both enzymes by ${\beta}-naphthoquinone-4-sulfonic$ acid suggests the involvement of lysine at their active sites. $Cu^{2+}$ was a potent inhibitor to G6PDH-2, but a lesser degree to G6PDH-1. Both G6PDH-1 and G6PDH-2 showed an optimum activity at pH 8.0 and $30^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.848-854
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• 2012

We have studied the oligomerization of a fibril-forming segment of ${\alpha}$-Synulcein using a replica exchange molecular dynamics (REMD) simulation. The simulation was performed with trimers and tetramers of a 12 amino acid residue stretch (residues 71-82) of ${\alpha}$-Synulcein. From extensive REMD simulations, we observed the spontaneous formation of both trimer and tetramer, demonstrating the self-aggregating and fibril-forming properties of the peptides. Secondary structure profile and clustering analysis illustrated that antiparallel ${\beta}$-sheet structures are major species corresponding to the global free energy minimum. As the size of the oligomer increases from a dimer to a tetramer, conformational stability is increased. We examined the evolution of simple order parameters and their free energy profiles to identify the process of aggregation. It was found that the degree of aggregation increased as time passed. Tetramer formation was slower than trimer formation and a transition in order parameters was observed, indicating the full development of tetramer conformation which is more stable than that of the trimer. The shape of free energy surface and change of order parameter distributions indicate that the oligomer formation follows a dock-and-lock process.

• Applied Biological Chemistry
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• v.41 no.4
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• pp.235-240
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• 1998

The myristoyl-acyl carrier protein (ACP) specific thioesterase from Iris tectorum was purified to a considerable homogeneity and characterized. The enzyme was eluted with a considerable stability by double-gradients using Triton X-100 and low ionic KCl or Na-phosphate through DEAE-52, Octyl-Sepharose, Q-Sepharose, and hydroxyapatite chromatoraphy. SDS-PAGE analysis showed a single band of 39 kDa. The native molecular weight was estimated to be 82 kDa by Sephacryl S-200 chromatography, indicating that the enzyme was a dimer. The thioesterase showed a chain-length specificity to myristoyl-ACP in preference to other-ACPs. The enzyme activity decreased by 1.0 mM myristate to about 27% of the original activity, whereas the remaining activity with decanoate was about 90%. The purified thioesterase was inhibited by myristoyl-CoA more than by myristate, suggesting that the myristoyl-AGP thiolesterase might be controlled by myristic acid and/or a subsequent product myristoyl-CoA. In addition, some biochemical characteristics of the enzyme were described.

• Natural Product Sciences
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• v.17 no.3
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• pp.202-205
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• 2011

The Angelica root has been used as a medicinal herb in many Asian countries including Korea, China, and Japan. Angelica gigas, A. sinensis, and A. acutiloba have been considered as Angelicae radix in Korean, Chinese, and Japanese Pharmacopoeia, respectively. Since the origins of Angelicae radix differ from country to country, there is a need to develop an efficient analytical method to identify the origin of the Angelica root. In order to obtain chemical fingerprints, three different Angelicae Radices were analyzed by direct analysis in real time mass spectrometry (DART-MS). Significantly different DART-MS spectra were observed from three different species of Angelicae Radix. Strong peaks of decursin or decusinol angelate, and its dimer were exclusively found from A. gigas. Ligustilide and linoleic acid were detected as the major component from A. acutiloba. The strongest ligustilide peak was observed from A. sinensis. DART-MS fingerprinting is a promising method for the rapid identification and/or quality control of Angelicae Radix.