• 생명과학회지
• /
• 제5권4호
• /
• pp.155-161
• /
• 1995

The effects of substrate concentration, enzyme concentration, reaction temperature, and water content were investigated in intramolecular esterification. This study used cyclohexane as organic solvent, power lipase as enzyme, and benzyl alcohol and octanoic acid as substrate. The initial reaction rate was found to be proportional to enzyme concentration; followed Michaelis-Menten equation for octanoic acid; and was inhibited by benzyl alcohol . The observed initial reaction rate first increased, then decreased with increasing reaction temperature, giving rise to the maximum rate at 20$\circ$. The drop in the reaction rate at higher temperature was to partition equilibrium change of substrate between organic solvent and hydration layer of enzyme molecule in addition to the deactivation by enzyme denaturation. Water layer surrounding enzyme molecule seemed to activate in organic solvent and the realistic reaction was done in the water layer. In the enzymatic reaction in organic solvent, the initial reaction rate was influenced by partition quilibrium of substrate, so the optimum condition of substrate concentration, enzyme concentration, reaction temperature, and water content would give a good design tool.

• Journal of Microbiology and Biotechnology
• /
• 제9권1호
• /
• pp.1-8
• /
• 1999

Most carbohydrates exist in nature in an insoluble state, which reduces their susceptibility towards various carbohydrases. Accordingly, they require intensive pretreatment for structural modification to enhance an enzyme reaction. The direct conversion of insoluble carbohydrates has distinct advantages for special types of reaction, especially exo-type carbohydrase; however, its application is limited due to structural constraints. This paper introduces two novel heterogeneous enzyme reaction systems for direct conversion of insoluble carbohydrates; one is an attrition coupled enzyme reaction system containing attrition-milling media for enhancing the enzyme reaction, and the other is a heterogeneous enzyme reaction system using extruded starch as an insoluble substrate. The direct conversion of typically insoluble carbohydrates, including cellulose, starch, and chitin with their corresponding carbohydrases, including cellulase, amylase, chitinase, and cyclodextrin glucanotransferase, was carried out using two proposed enzyme reaction systems. The conceptual features of the systems, their reaction characteristics and mechanism, and the industrial applications of the various carbohydrates are analyzed in this review.

• Journal of Microbiology and Biotechnology
• /
• 제16권11호
• /
• pp.1678-1683
• /
• 2006

A novel suspension-phase enzyme reaction system for the intermolecular transglycosylation of L-ascorbic acid into 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid supplementing extrusion starch as the glycosyl donor was developed using cyclodextrin glucanotransferase from Thermoanaerobacter sp. A high conversion yield compared to the conventional soluble-phase enzyme reaction system using cyclodextrins and soluble starch was achieved. The optimal reaction conditions were 2,000 units of cycIodextrin glucanotransferase, 20 g/l of L-ascorbic acid, and 50 g/l of extrusion starch at $50^{\circ}C$ for 24 h. The new suspension-phase enzyme reaction system also exhibited several distinct advantages other than a high conversion yield, including a lower accumulation of oligosaccharides and easily separable residual extrusion starch by centrifugation or filtration in the reaction mixture, which will facilitate the purification of 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid. The new suspension-phase enzyme reaction system seems to be potentially applicable as the industrial process for the production of thermally and oxidatively stable 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid.

• 대한기계학회논문집A
• /
• 제28권10호
• /
• pp.1598-1602
• /
• 2004

In this paper, we report a microthermostat using PDMS (poly-dimethylsiloxane) and glass. This PDMS/glass chip is able to maintain constant temperature that is necessary for restriction enzyme reaction. Since PDMS is the low-cost and the mass-producible material and has very good biochemical compatibility, PDMS chip has more benefit than general Si chip. Heater was made of Au wiring patterned on Pyrex glass. A reaction chamber has a capacity of about 3 ${mu}ell$. We performed a restriction enzyme reaction by using the fabricated microthermostat and conventional method. Then, with the electrophoresis, we made a comparison between the result from the micro reactor and the one from conventional method.

• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 1986년도 추계학술대회
• /
• pp.525.2-525
• /
• 1986

Cephalexin synthesizing enzyme (${\alpha}$ amino acid ester hydrolase) was partially purified from the culture broth of Acetobacter turbidans ATCC9325 through ammonium sulfate fractionation, DEAE, CM, and Sephacryl S-200 gel filtration. The enzyme has optimum pH 6.0 and temperature, 40$^{\circ}C$ respectively. From the analysis of reaction mixtures by thin layer chromatographic and high performance liquid chromatographic techniques, it was confirmed this enzyme catalyzed simultaneously the following reactions : 1) Synthesis of cephalexin from D-${\alpha}$-phenylglycine methylester (PGM) and 7-amino 3-deacetoxy-cetoxycephalosporanic acid (7-ADCA) 2) Hydrolysis of cephalexin to form 7-ADCA and phenylglycine (PG) 3) Hydrolysis of PGM to form PG and methanol. Base on the above experimental observations, the reaction model of this enzyme was identical with that of the enzyme from Xanthomonas citri.

• 미생물학회지
• /
• 제18권2호
• /
• pp.59-66
• /
• 1980

Two strains S-P and S-P-2, both Streptomyces sp., have been isolated and were found to have relatively high specific enzyme activity compared to other organisms reported. The specific activity of the enzyme produced from these two strains were 0.25 and 0.2 international units respectively. The productivity of the enzyme achieved was about 50 IU/l/hr. Glucose isomerase form these strains was found to be stable under the temperature of heat treatment (at $65^{\circ}C$) for fixation of enzyme inside the dell. This organism has an advantage in that it did not require toxic metalic ion for enzyme activity and could utilize xylan in leu of xylose as an inducer. The optimal temperature and pH of enzymatic reaction purpose of using these data for the optimal operation and designing of enzyme reactor system. The reaction mechanism was found to follow the single substrate reversible reaction kinetics. The kinetic constants determined experimentally are : $K_{mf}=0.33M,\;K_{mb}=1.0M,\;V_{mf}=0.88{\mu}mole\;per\;min.,\;V_{mb}= 2.96{\mu}mole\;per\;min.\;and\;K_{eq}=0.74.

• Journal of Ginseng Research
• /
• 제7권1호
• /
• pp.88-93
• /
• 1983

Studies were carried out to elucidate the protein stabilizing effect of ginseng. Malate dehydrogenase (EC 1.1.1.37) was used as a protein and the rate constant of the enzyme inactivation was determined under the heat denaturation condition. There was an optimum pH for the enzyme stability, the rate constant of the enzyme inactivation was minimum at BH 8.8. The rate constant was increased at lower and higher pH regions than the optimum pH. The inactivation reaction followed the Arrehnius law and the activation energy was measured as 36.8kcal/mole. The reaction rate was not affected by the enzyme concentration and thus it was assumed to be unimolecular first order reaction. The water extract of red ginseng decreased the rate constant of Malate dehydrogenate under heat inactivation condition to stabilize the enzyme activity. Purified ginseng saponin also stabilized the enzyme against heat inactivation.

• KSBB Journal
• /
• 제11권6호
• /
• pp.712-717
• /
• 1996

셀룰라아제, polyoxyethylene 유도체와 maleic acid anhydride의 공중합고분자로 중합한 수식셀룰 라아제를 제조하고, 당화 특성과 효소 반응 속도론 등을 검토하였다. 수식 반응에서, 공중합고분자-효소 질량비가 증가함에 따라 수식률은 증가하며, 질량비 4 이상에서는 수식률이 일정하였다. 이 때 최 대수식률은 55% 이며 최대수식률의 수식생룰라아제 는 75%의 높은 효소활성을 나타내었다. 수식효소와 미수식효소의 당화 실험에서, 수식효소가 전 반응시 간에 걸쳐 미수식효소보다 높은 당화반응안정성을 유지하였으며, 그로 인해 최종 전화율은 수식효소가 더 큰 값을 가졌다. 기질에의 강한 흡착으로 인한 효소 deactivation을 고려한 반응식을 적용한 결과, 생 성환원탕놓도의 실험값과 계산치는 잘 일치하였다. 그로부터 반응속도상수를 구하고 생성환원당농도와 유리효소농도의 모사그래프를 구할 수 있었으며, 반 응시간에 따른 유리효소의 농도를 수치모사한 결과, 미수식효소에 비해 수식효소의 유리효소 농도가 더 높았고 그로 인해 더 높은 당전화율을 나타내였다.

• KSBB Journal
• /
• 제11권5호
• /
• pp.511-517
• /
• 1996

본 연구에서는 친수성기질과 소수성기질을 함께 수용하는 수용성 상용용매를 사용하여 반응매질의 친수성과 소수성이 알킬글루코시드의 합성반응에 적 합하도록 조절된 양친매질을 개발하고 hydrophili C city control이 이루어진 효소반응기술을 이용하여 효소의 활성도와 안정성, 기질의 가용화, 얄킬글루코 시드의 수율과 농도의 관점에셔 가장 바람직한 양친 매상 효소반응공정 (amphiphilic phase enzyme re action process)을 제시하였으며, 핵실글루코시드, 옥틸글루코시드, 데실글루코시드 및 도데실글루코시 드를 합성한 결과 생생물 농도는 각각 18.2, 9.68, 7.27, 6.03g/L을 얻였다.

• 한국미생물·생명공학회지
• /
• 제23권4호
• /
• pp.425-431
• /
• 1995

A kinetic model of the cyclodextrin formation in a heterogeneous enzyme reaction system using swollen extrusion starch as substrate was derived emphasing the structural features of extrusion starch. The degree of gelatinization, the ratio of accessible and inaccessible portion of extrusion starch, adsorption of CGTase on swollen starch, the structural transformation during reaction, and product inhibition caused by produced CDs were considered in deriving kinetic model. Various kinetic constants were also evaluated. The derived kinetic equation was numerically simulated, which result showed that the derived kinetic equations can be used to predict the experimental data reasonably well under the various experimental conditions. Kinetic model can be utilized for the optimization of enzyme reactor and the process development for CD production from swollen extrusion starch.