• Journal of Microbiology and Biotechnology
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• 제25권5호
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• pp.718-722
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• 2015

Techniques for immobilizing effective enzymes on nanoparticles for stabilization of the activity of free enzymes have been developing as a pharmaceutical field. In this study, we examined the effect of three different pH conditions of phosphate buffer, as a dissolving solvent for lysosomal enzymes, on the direct immobilization of lysosomal enzymes extracted from Hen's egg white and Saccharomyces cerevisiae. Titanium(IV) oxide (TiO₂) nanoparticles, which are extensively used in many research fields, were used in this study. The lysosomal enzymes immobilized on TiO₂ under each pH condition were evaluated to maintain the specific activity of lysosomal enzymes, so that we can determine the degree of melanin treatment in lysosomal enzymes immobilized on TiO₂. We found that the immobilization efficiency and melanin treatment activity in both lysosomal enzymes extracted from Hen's egg white and S. cerevisiae were the highest in an acidic condition of phosphate buffer (pH 4). However, the immobilization efficiency and melanin treatment activity were inversely proportional to the increase in pH under alkaline conditions. In addition, enhanced immobilization efficiency was shown in TiO₂ pretreated with a divalent, positively charged ion, Ca²⁺, and the melanin treatment activity of immobilized lysosomal enzymes on TiO₂ pretreated with Ca²⁺ was also increased. Therefore, this result suggests that the immobilization efficiency and melanin treatment activity of lysosomal enzymes can be enhanced according to the pH conditions of the dissolving solvent.

• 한국멀티미디어학회논문지
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• 제12권3호
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• pp.345-353
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• 2009

P2P 온라인 게임 시스템에서 대규모 사용자의 동시 접속을 수용할 수 있는 안전한 게임 운영 시스템이 필수적이다. 본 논문에서 제안하는 P2P 온라인 게임 시스템은 RS(Region Server)들의 재구성 및 RS간의 상호 정보 교환을 통해 한 영역에 플레이어가 집중되는 현상을 피하여 대규모 플레이어를 수용할 수 있으며, 안전한 게임을 운영할 수 있다. 또한 모니터링 서버의 광역 버퍼(Global Zone Buffer)를 이용한 부하분산으로 타임스탬프 시간 내의 게임 동기화가 가능하며, 미들웨어를 단위 영역별로 관리하여 게임 월드의 크기에 관계없이 수행 가능하다. 따라서, 고비용의 서버 추가 문제 및 메시지 전송의 안정성을 확보할 수 있다. 또한, 시뮬레이션을 통하여 제안 시스템에 대한 효율성을 입증한다.

• 한국가축번식학회지
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• 제22권4호
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• pp.405-410
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• 1998

본 연구는 독자 개발한 돼지액상정액희석제 Kp(한국생명과학연구소)에 pH를 안정화하여 보존 중 정자의 운동성을 유지시킬 수 있도록 EDTA, Tris, Citrate buffer의 적정 첨가농도를 결정하고자 실시하였다. Basic Kp와 BTS (Mini-tube, Germany; BT-Sg), BTS (Tri-bio, USA; BTSa), Modena (SGI, USA)를 17$^{\circ}C$ 에서 각각 보관한 경우 모든 희석액에서 시간 경과에 따라 pH가 증가하였고, Basic Kp 는 희석 당일의 pH가 다른 희석액에 비해 높게 나타났는데 이것은 돼지액상정액의 생리적인 pH인 6.8~7.5에 비해서도 높은 수준이었다. 정액내의 pH 저하를 방지해 주고 정액의 생리적인 pH를 유지하기 위하여 Basic Kp에 EDTA, Tris, Citrate buffer를 단계적으로 첨가하면서 시간 경과에 따른 pH 변화를 살펴 본 결과 1.25g /L EDTA, 1.42g /L Tris, 1.00g /L Citrate를 첨가한 경우 (Modified Kp) pH는 l일째 6.88에서 6일째 7.33으로 유지되었다. 특히, Modified Kp에 첨가된 buffer 의 농도는 Modena와 다른 희석제에 첨가된 농도에 비해 1/2 에서 1/4 정도로 낮은 수준이었다. Modified Kp 와 Basic Kp, BTSg, BTSa 및 Modena로 냉동-융해된 돼지 정자를 희석하여 보존한 경우 정자의 운동성은 Modified Kp가 다른 희석액에 비해 유의하게 높게 나타났다(87.0% vs. 71.0~48.0% in day 1; 13.3% vs. 6.3~0% of day 6), 이상의 결과를 종합해 볼 때, Modified Kp는 낮은 농도의 EDTA, Tris, Citrate buffer 첨가에도 불구하고 돼지정자의 생리적인 pH 수준을 잘 유지할 수 있었으며, 수입되어 냉동-융해된 돼지 정자에 사용하는 희석제 BTSg, BTSa, Modena 보다도 정자의 운동성에 효과적이었다.

• Journal of Pharmaceutical Investigation
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• 제26권3호
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• pp.175-185
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• 1996

To inhibit the enzymatic degradation of leucine enkephalin (Leu-Enk) and its synthetic analog. $[D-ala^2]$-leucine enkephalinamide (YAGFL), in the nasal, rectal and vaginal mucosal and serosal extracts of rabbits, effects of enzyme inhibitors such as amastatin (AM), puromycin (PM), thiorphan (TP), thimerosal (TM), EDTA, N-carboxymethyl-Phe-Leu (CPL), phenylethyl alcohol (PEA), phenylmercuric acetate (PMA), benzalkonium chloride (BC) and modified cyclodextrins, alone or in combination, were observed by assaying the pentapeptides staying intact during incubation. Mucosa extracts were prepared by exposing freshly-excised mucosal specimens mounted on Valia-Chien cells to isotonic phosphate buffer while stirring. The degradation of Leu-Enk and YAGFL followed the apparent first-order kinetics. The half-lives (mean) in the nasal, rectal and vaginal mucosal extracts were found to be 1.07, 0.33 and 1.14 hr for Leu-Enk, and 16.9, 6.2 and 6.8 hr for YAGFL, respectively. AM or PM, which is an aminopeptidase inhibitor, did not show a sufficient inhibition of Leu-Enk $(50\;{\mu}g/ml)$ degradation in all kinds of extracts. $Dimethyl-{\beta}-cyclodextrin\;(DM-{\beta}-CyD)$ decreased the degradation rate constants of Leu-Enk about 2 or 3 times, comparing with no additive. However, the use of mixed inhibitors of AM $(50\;{\mu}M)$/TM (0.25 mM)/EDTA (5 mM) resulted in a full stabilization of Leu-Enk by decreasing the degradation rate constants 67.3, 161.3 and 113.8 times far the nasal, rectal and vaginal mucosal extracts, respectively, comparing with no inhibitor. With mixed inhibitors, Leu-Enk remained intact more than 90% after 6 hr-incubation. In the stabilization of YAGFL, hM, TP or CPL alone showed little efffct, and some additives demonstrated a considerable inhibition of YAGFL degradation in the rank order of TM > BC > EDTA. However, the addition of mixed inhibitors such as TM (0.5 mM) and EDTA (5 mM) into the extracts protected YAGFL from the degradation by more than 85% even after 24 hr-incubation, suggesting almost complete inhibition of YAGFL degradation in the extract. On the other hand, $DM-{\beta}-CyD\;or\;hydroxypropyl-{\beta}-cyclodextrin$ (10%) were also found to retard enzymatic degradation rates of YAGFL markedly, and resulted in staying intact more than 80% of YAGFL in the nasal and vaginal mucosal extracts, and more than 60% in the rectal mucosal extract after 16 hr-incubation.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.211-211
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• 2003

PbTiO$_3$ 씨앗층을 이용하여 완화형 강유전체 Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$ (PMT) 박막의 페로브스카이트 상안정화와 열처리 조건에 따른 미세구조변화, 이에 따른 전기적 특성 변화에 관하여 조사하였다. PbTiO$_3$ 박막을 스핀코팅법으로 3000 rpm에서 20초간(111) 방향으로 배향된 Pt / Ti / SiO$_2$/ Si 기판에 증착하여 안정화된 페로브스카이트 박막을 얻었다. 이렇게 제조된 PbTiO$_3$를 Buffer 층으로 사용하고 그 위에 Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$를 박막을 Spin coating방법으로 증착한 후, 급속열처리 방법(RTA)으로 550- $650^{\circ}C$ 사이에서 열처리하였다. 제조된 박막의 열처리 온도에 따른 미세구조 변화와 결정성을 XRD, SEM, TEM으로 분석하였고 박막의 저온 강유전 특성을 RT66A를 이용하여 평가하였다. Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$ 박막의 경우 씨앗층이 없는 경우에는 pyrochlore상이 주상이었지만 씨앗층을 사용한 경우 페로브스카이트 상이 주상임을 확인하였고 열처리 온도가 증가할수록 페로브스카이트상의 상대적 양이 증가함을 확인하였다. 미세구조와 상의 변화에 따른 전기적 특성 변화에 관하여 자세하게 논의할 것이다.

• 한국물환경학회지
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• 제25권1호
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• pp.84-89
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• 2009

Our nation's water resources remain susceptible to contamination by phenolic agrichemicals. These compounds can be toxic to a variety of organisms including humans. Their disposal is restricted in many countries with strict limits for acceptable concentrations in drinking water. Enzyme-mediated in situ stabilization has been advocated as an approach for the treatment of phenolic compounds in soils and groundwater. This study reports the development of a new approach to quantify the activity of the HRP enzyme in aqueous systems. The method is based on the coupled processes of energy transfer and enhanced chemiluminescence using a luminol-$H_2O_2$-HRP system. In this study, the effects of solution pH, ionic strength and aqueous concentrations of HRP, $H_2O_2$ and enhancer were evaluated on the p-iodophenol-enhanced, HRP-catalyzed chemiluminescence reaction intensity in Tris-HCl buffer. All assay components were found to affect the maximum chemiluminescene intensity. The calibration curve for HRP showed the linear relationship with maximum light intensity.

• 한국식품영양학회지
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• 제3권2호
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• pp.123-132
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• 1990

Sweet potato $\beta$-amylase is a tetrameric enzyme consisting of four identical polypeptide chains with a molecular weight of 5.6$\times$104, though most of the other $\beta$-amylases are monomeric enzymes. But, the relationship between subunit structure and catalytic function of the enzyme is not known. This study was done to know what the function of the subunit structure of the enzyme is. We obtained the monomer from the enzyme by the treatment of SDS, alkali pH buffer and urea. But the monomer had not activity. We tried to prepare the active monomer from the enzyme by the modification with periodate-oxidized soluble starch , In the result, we succeeded in isolating an active monomer as an oxidized soluble starch-conjugated form The active monomer had 57% of the original activity, 13.2% of the sugar and the molecular weight was estimated to be 5.4$\times$104. This results suggest that the tetrameric form of the enzyme is a most stable one and exists in nature, and the subunit structure of the enzyme Plays an important role in stabilization but not catalytic function.

• 한국식품영양과학회지
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• 제24권3호
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• pp.355-361
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• 1995

Lipoprotein lipase(LPL) is an acylglycerol hydrolase and is the extrahepatic enzyme responsible for the hydrolysis of triglyceride-rich plasma lipoproteins. LPL has been isolated from bovine milk by affinity chromatography on heparin-sepharose in 2M NaCl, 5mM barbital buffer, pH 7.4. Para-nitrophenyl butyrate(PNPB) was used as a substrate for the determination of LPL activity. Molecular weight of LPL was 55KD on 10% SDS-PAGE. When the effects of heparin on LPL activation were compared, LPL activity of heparin added group increased approximately 5 times higher than that of heparin non-added groups. These results indicated that heparin involved in the stabilization of LPL structure that led to increase enzyme activity. Furthermore, LPL activity increased about 4 times compared to the absence of heparin at various pH. LPL was stabilized when heparin was added either low or high salt concentrations. With the presence of heparin, NaCl concentration did not affect LPL activity at pH range 6∼9.

• Journal of Pharmaceutical Investigation
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• 제29권3호
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• pp.205-210
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• 1999

To formulate the parenteral delivery of a new cephalosporin derivative, 7-${\beta}$-[(2)-2-(2-arninothiazol-4-yl)-2methoxyiminoacetamido]- 3- [(2,3-cyclopenteno-4-carbamoyl-l-pyridinium)methyl]- 3-cephem-4-carboxylate sulfate( CKD604), the stability and solubility of CKD-604 in various aqueous media were investigated. The degradation kinetics of CKD-604 in aqueous solutions (ionic strength 0.1, pH 1-8) were studied at $37^{\circ}C$. The observed degradation rates followed pseudo first order kinetics. The pH-rate profile exhibited a minimum degradation rate at pH 5. The Arrhenius activation energy was 14.2 kcal/mol in pH 5 buffer solution. Excellent agreement between the cephalosporins' theoretical pH-rate profile and the experimental data indicated that the degradation pathway of CKD-604 could be predicted according to the general pathway of cephalosporins. The solubility of CKD-604 was 8.16 mg/ml at $25^{\circ}C$. To enhance the solubility and adjust the suitable pH, CKD-604 was solubilized by using sodium ascorbate, ascorbic acid and urea. The compositions were obtained to satisfy optimum pH and concentration, and the total amount of additives was several times of the active ingredient, CKD-604.

• 한국식품과학회지
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• 제52권2호
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• pp.200-203
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• 2020

SS은 식물성 스테롤로서 인체에 유익한 생리활성을 나타낸다. 리포솜 인지질을 PC과 SS로 구성하고, ASA를 탈수/재수화 방법에 의해 포집시킨 후, ASA의 안정성을 분석하였다. 리포솜의 평균 크기는 SS 함량이 증가할수록 증가하였으며, SS는 포집된 ASA의 안정성을 향상시켰다. 예를 들어, 완충용액에 존재하는 ASA는 4℃에서 8일간 저장하면 7.66%가 잔존하지만, 100:0, 90:10, 70:30 (PC/SS)로 조성된 리포솜에 포집된 ASA는 같은 조건에서 각각 34.12, 49.88, 58.58%가 잔존하였다. 이러한 결과는 리포솜에서 SS가 포집된 ASA의 안정성을 향상시킴을 의미한다.