소 뇌막으로부터 5'-Nucleotidase의 효소적 용출에 대한 내재계면활성제의 효과

류희문,석대은 충남대학교 약학대학 의약품개발연구소 2000 藥學論文集 Vol.16 No.-

Glycosylphosphatidylinositol (GPI)-linked 5'-nucleotidase is released as both amphiphilic form (Amp-nucleotidase) and hydrophilic form (Hyd-nucleotidase) from bovine brain membrane. Exposure of brain membrane to deoxycholate, lysolecithin or monooleoylglycerol leads to a concentration-dependent release of Hyd-nucleotidase with deoxycholate being the most effective. Next, the brain GPI-PLD-catalyzed conversion of Amp-nucleotidase to Hyd-nucleotidase was investigated. The GPI-PLD-catalyzed conversion of required detergents, and among detergents used, monooleoylglycerol was the most effective for the enzymatic conversion. Monooleoylglycerol exhibited a concentration-dependent effect on GPI-PLD activity up to 0.3 mM, but its effect decreased at 1 mM. In addition, the combinational effect of monooleoylglycerol and lysolecithin on GPI-PLD action was not significant. Based on these results. it is suggested that the formation of Hyd-nucleotidase in brain tissue may be ascribed to the activities of GPI-PLC and GPI-PLD in the presence of bio-detergent.

합성품 Peptide와의 비교실험을 통한 Bovine Thyroglobulin의 50K Polypeptide내에 존재하는 Diiodotyrosine-1375의 구조동정

류희문,석대은 충남대학교 약학대학 의약품개발연구소 2000 藥學論文集 Vol.16 No.-

A peptide fragment containing residues 1218-1591, prepared from thermolysin-mediated proteolysis of bovine thyroglobulin, was reduced by dithiothreitol and then treated with iodoacetic acid. The carboxymethylated peptide was digested with endoproteinase Asp-N, and fractionated by RP-HPLC. The fractions were analyzed by LC/ESI-MS for the monitor of a peptide with a hormonogenic site at Tyr-1375, and a fraction was found to contain to a peptide (residues 1366-1381) containing Tyr-1375. This observation was positively confirmed by the comparison with synthetic peptide, DVEEALAGK (diiodotyrosine) LAGRFA, which was produced from the oxidative iodination of DVEEALAGKYLAGRFA by lactoperoxidase employing KI and (H_2)(O_2)-generating system.

소 뇌 조직으로부터 5'-Nucleotidase의 정제 및 특성규명

류희문,석대은 충남대학교 약학대학 의약품개발연구소 2002 藥學論文集 Vol.17 No.-

5'-Nucleotidase, bound to brain membranes as a glycosylphosphatidyl-inositol (GPI)-anchored protein, is responsible for the conversion of adenosine-5'-monophosphate into adenosine, which is an agonist in adenosine receptor signalling. Here, 5'-nucleotidase was isolated from bovine brain using PI-PLC treatment, and purified by concanavalin A sepharose chromatography, DEAE-sephacel chromatography, and finally AMP affinity chromatography. For higher yield of enzyme purification, Zn^2+ was Included in the elution buffer in DEAE-sephacel chromatography. Especially, NaCl was more favorable than MgCl_2 for the elution of 5'-nucleotidase, proper for inactivation study, from AMP affinity column. The purified 5'-nucleotidase was relatively pure on SDS-PAGE analysis, showing a specific activity of 30.27 μmole/min/㎎ (purification fold 19,000 fold). The purified enzyme, possessing a K_m value of 44μM and an optimum pH of 7.5, was inhibited competitively by ATP (K_i, 12 μM), and uncompetitively by cysteine (K_i, 0.32 mM). In addition, the enzyme was activated slighty (1.5-folds) by Mg^2+.

효소 Lipoxygenase의 신규기질 : Acylglycerol, acylethanolamide, lysophospholipids 및 phospholipids

황룡쌍,류희문,박천호,석대은 충남대학교 약학대학 의약품개발연구소 2007 藥學論文集 Vol.22 No.-

Lipoxygenase belongs to a diverse family of nonheme ferroproteins that oxygenate polyenoic fatty acids containing 1,4-pentadiene structure to form their corresponding hydroperoxy derivatives. Lipoxygenases (LOXs), widely distributed in animals and plants, have a key function in the formation of biologically active substances from pulyunsaturated fatty acids. Generally, free polyunsaturated fatty acids, liberated from membrane phospholipids via phospholipase-catalyzed hydrolysis, are used as substrates for LOXs. Although it is acknowledged that free polyunsaturated fatty acids are preferred to phospholipids or triglycerides as substrates, there have been recent reports that mammalian enzymes can oxidize certain phospholipids. Especially, reticulocyte LOX (15-LOX) leukocyte 15-LOX, leukocyte LOX (12-LOX) can oxygenate complex substrates such as phospholipids and biomembranes. In addition, acylglycerol and acylethanolamide are utilized by lipoxygeanse as well as cycoloxygenase; the latter enzyme contributes to generation of bioactive prostanoids derivative. Furthermore, lysophosphatidylcholine or lysophosphatidic acid containing linoleoyl or arachidonoyl moieties are known to be oxygenated by reticulocyte LOX, leukocyte 15-LOX or leukocyte-type 12-LOX; oxygenated lysophospholipids can play a carrier role in transporting oxygenated derivatives. Thus, the use of various lipid substrates as new substrates for lipoxygenase may extend the physiological roles of those lipids containing unsaturated fatty acyl chains.

Cumene hydroperoxide에 의한 paraoxonase 1의 산화적 불활성화에 대한 보호 방안

스, 위엥쥐,류희문,김주령,석대은 충남대학교 약학대학 의약품개발연구소 2003 藥學論文集 Vol.18 No.-

Paraoxonase 1 (PON1), an enzyme associated with high density lipoprotein (HDL), is known to protect low density lipoprotein (LDL) from lipid peroxidation involving copper ion. However, Paraoxonase 1 activity was observed to decrease during LDL oxidation. Here, the inactivation of PON1 by various peroxides was examined. Paraoxonase 1, purified from human plasma, was subjected to cumene hydroperoxide, hydrogen peroxide or tert-butyl hydroperoxide. PON activity, based on the hydrolysis of phenyl acetate, decreased by approximately 40 and 38 %, respectively, after the exposure to 2mM cumene hydroperoxide and hydrogen peroxide, while tert-butyl hydroperoxide had no remarkable inhibitory effect. Next, the compounds capable of preventing against cumene hydroperoxide-induced inactivation of PONl were screened. While quercetin or phenyl acetate failed to protect PON1, lauric acid or calcium chloride was found to protect PONl from cumene hydroperoxide-induced inactivation. Especially, lauric acid appeared to show the greater protection than the other fatty acids tested. In further study, lauric acid showed a dose-dependent protection with an E& value of around 35 μM. Based on these results, It is proposed that the alky hydroperoxide-induced inactivation of Paraoxonase 1 can be prevented by a proper fatty acid recipe.

인체 혈장 Paraoxonase의 산화적 불활성화

위엥쥐스,김주령,정태숙,류희문,석대은 충남대학교 약학대학 의약품개발연구소 2002 藥學論文集 Vol.17 No.-

Paraoxonase (PON), an enzyme associated with high density lipoprotein (HDL), is known to protect low density lipoprotein (LDL) from lipid peroxidation involving copper ion. However, PON activity was observed to decrease during LDL oxidation. Here, we attempted to elucidate the possible mechanism for the inactivation of PON. PON was partially purified from human plasma, and subjected to various oxidant systems. PON activity, based on the hydrolysis of phenyl acetate, decreased slightly after the exposure to H_2O_2 or ascorbate, while oxidants such as peroxynitrite or HOCl had no remarkable effect. Inclusion of Cu^2+ in the incubation with ascorbate (0.3∼1 mM) led to a rapid decrease of activity in a time-and concentration-dependent manner. In comparison, ascorbate/Cu^2+ system was much more effective than ascorbate/Fe^2+ system in inactivating PON. A further study indicates that general hydroxyl radical scavengers such as mannitol, ethanol or benzoate failed to prevent the PON inactivation. Based on these results, it is proposed that the PON inactivation during LDL oxidation may be ascribed mainly to the Cu^2+-catalyzed oxidation.

Knowledge Acquisition Approach Based on Rough Set in Online Aided Decision System for Food Processing Quality and Safety

Liu Peng,Liu Wen,Li Qiang,Yang Li,Duan Min,Dai Yue 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.6

For the problem that the use effect of food processing information system is poor due to absence of knowledge acquisition measures and knowledge self-updating function, a knowledge acquisition approach based on rough set is put forward. First, the approach establishes a set of predicted samples for the relationship between food processing parameters and product quality; then uses the discretization of continuous attribute, attribute reduction and rule extraction algorithm of rough set to acquire automatically predicted knowledge from a large number of predicted sample sets, and then saves the predicted knowledge in the knowledge base of expert system; finally, realizes the extraction of knowledge of food processing process based on the inference engine, which greatly enhances the effectiveness and practicality of the acquired knowledge in online aided decision system of the food processing quality and safety.

“Nothing” as Head and “Things” as Beginning: Zhuangzi and Shen Dao on EqualizingThings

Liu Dai 영남퇴계학연구원 2019 The Journal of Toegye Studies Vol.2 No.2

Starting from “equalizing all things”, Shen Dao develops the life philosophy of “rolling and swirling along with things” and the political theory of respecting the law and emphasizing the people. Based on “everything exists”, his theory of equalizing things shows respect to differences and the objective value of things, requiring to act along with things at the cost of agency. Yet Zhuangzi believes in an ultimate state when “before things exist”, and tries to equalize “things” with “nothing”. His philosophy embraces a complete picture from before the beginning of things to after there are already things, in which “things” are merely the temporary appearanceof the Creation-Transformation in an inferior level. Having found the origin of “things”, i.e. “the Way”, the spirit is able to go beyond limits of things toward the state of independently rambling.

Design and Prediction of Three Dimensional Flows in a Low Speed Highly Loaded Axial Flow Fan

Liu, Xuejiao,Chen, Liu,Dai, Ren,Yang, Ailing Korean Society for Fluid machinery 2013 International journal of fluid machinery and syste Vol.6 No.2

This paper describes the design to increase the blade loading factor of a low speed axial flow fan from normal 0.42 to highly loaded 0.55. A three-dimensional viscous solver is used to model the flows in the highly-loaded and normal loaded stages over its operation range. At the design point operation the static pressure rise can be increased by 20 percent with a deficit of efficiency by 0.3 percent. In the highly loaded fan stage, the rotor hub flow stalls, and separation vortex extends over the rotor hub region. The backflow, which occurs along the stator hub-suction surface, changes the exit flow from the prescribed axial direction. Results in this paper confirm that the limitation of the two dimensional diffusion does not affect primarily on the fan's performance. Highly loaded fan may have actually better performance than its two dimensional design. Three dimensional designing approaches may lead to better highly loaded fan with controlled rotor hub stall.

Conformational Transitions of Polymer Brushes for Reversibly Switching Graphene Transistors

Liu, Song,Jamali, Safa,Liu, Qingfeng,Maia, Joao,Baek, Jong-Beom,Jiang, Naisheng,Xu, Ming,Dai, Liming American Chemical Society 2016 Macromolecules Vol.49 No.19

<P>We developed a facile, but efficient, approach to graphene field-effect transistors (FET) functionalized with polymer brushes, in which the conductance can be reversibly switched by solvent-induced polymer conformational changes. Our experimental and stimulation results demonstrated that the solvent-induced conformational transition of the polymer brush could affect the carrier concentration by changing the number of,scattering sites associated with the graphene-polymer contact areas, leading to reversible electrical switching for the graphene FET device. Both end-adsorbed diblock and triblock copolymers showed similar switching effect through the solvent-induced chain stretching-collapse and tail-to-loop conformational changes, respectively. This work provides new platform technologies for developing novel electronic devices with tunable electrical properties and for studying macromolecular conformations and conformational transitions.</P>