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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.
자기장이 있는 경우 결합무질서를 갖는 3D XY 모델의 상전이
류희문,차민철 한양대학교 이학기술연구소 2002 이학기술연구지 Vol.5 No.-
본 연구에서는 몬테칼로 시늉내기 방법을 사용하여 자기장에 의한 쩔쩔맴이 있는 경우 결합무질서가 있는 3차원 XY 모델의 상전이를 살펴본다. 그 결과 쩍쩔맴이 f = 1/2 인 경우 자기장 방향의 상관관계거리를 결정하는 임계지수로 z = 1.0이고, 자기장에 수직한 방향의 상관관계거리 임계지수로 v = 0.67을 얻었다. We have studied the phase transition in a bond-disordered 3D XY model using Monte Carlo methods in the presence of frustration due to a magnetic field. As a result, we obtain z = 1.0, which is the critical exponent characterizing the correlation length along the magnetic field, and v = 0.67, which is the correlation length exponent, when frustration is f = 1/2.
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+.
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.
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.