• 한국실천공학교육학회논문지
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• 제2권1호
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• pp.35-41
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• 2010

효소촉매반응은 통상적으로 반응속도가 매우 빠르고 동시에 높은 선택성을 보여 주는 특정이 있다. 단순 효소촉매 반응속도식을 보통 Michaelis-Menten식이라고 부른다. 효소의 활성을 간섭하는 화학물질을 저해제라고 하는데, 효소활성의 저해에는 가역적저해와 비가역적저해의 두 가지 형태로 나타난다. 만일 저해제가 수소결합과 같은 약한 결합으로 효소에 붙게 되면 이런 경우 효소저해는 가역적인 저해로 나타난다. 많은 효소 반응들은 그 반응으로부터 생성되는 생성물 자체에 의해서도 가역적 저해를 받게 된다. 생성물의 생성속도와 더불어 기질의 감소속도식은 비선형 미분방정식으로 나타 낼 수가 있다. 본 연구는 공학 분야의 학부교육을 목적으로 단순 효소반응속도식과 보다 더 복잡한 저해 효소반응속도식에 대한 수치해석의 결과를 보고 하고자 한다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권2호
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• pp.57-66
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• 2002

This review focuses on the use of immobilized lipase technology for the hydrolysis of oils. The importance of lipase catalyzed fat splitting process, the various immobilization procedures, kinetics, deactivation kinetics, New immobilized lipases for chiral resolution, reactor configurations, and process considerations are all reviewed and discussed.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권4호
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• pp.225-230
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• 2002

Experiments on deactivation kinetics of immobilized lipase enzyme from Candida cyl-indracea were performed in stirred bath reactor using rice bran oil as the substrate and temperature as the deactivation parameter. The data were fitted In first order deactivation model. The effect of temperature on deactivation rate was represented by Arrhenius equation. Theoretical equations were developed based on pseudo-steady state approximation and Michaelis -Menten rate expression to predict the time course of conversion due to enzyme deactivation and apparent half-life of the immobilized enzyme activity in PFR and CSTH under constant feed rate polity for no diffusion limitation and diffusion limitation of first order. Stability of enzyme in these continuous reactors was predicted and factors affecting the stability were analyzed.

• Animal cells and systems
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• 제8권4호
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• pp.307-312
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• 2004

Fast kinetics of transient pH changes and difference spectrum formation have been investigated following mixing of ADP/ATP with partially purified plasma membrane PM-ATPase of the pathogenic yeast Candida albicans in the presence of five nutrients: glucose, glutamic acid, proline, lysine, and arginine and two analogs of glucose: 2-deoxy D-glucose and xylose. Average $H^+$- absorption to release ratio, indicative of population of ATPase undergoing complete hydrolytic cycle, was found to be 0.27 for control. This ratio varied between 0.25 (proline) to 0.36 (arginine) for all other compounds tested, except for glucose. In the presence of glucose, $H^+$- absorption to release ratio was exceptionally high (0.92). While no UV difference spectrum was observed with ADP, mixing of ATP with ATPase led to a large conformational change. Exposure to different nutrients restricted the magnitude of the conformational change; the analogs of glucose were found to be ineffective. This suppression was maximal in the case of glucose (80%); with other nutrients, the magnitude of suppression ranged from 40-50%. Rate of $H^+$- absorption, which is indicative of E~P complex dissociation, showed positive correlation with suppression of conformational change only in the case of glucose and no other nutrient/analog. Mode of interaction of glucose with plasma membrane $H^+$-ATPase thus appears to be strikingly distinct compared to that of other nutrients/analogs tested. The results obtained lead us to propose a model for explaining glucose stimulation of plasma membrane $H^+$-ATPase activity.

• 센서학회지
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• 제3권2호
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• pp.16-23
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• 1994

오염수에서 유기인 화합물을 측정하기 위해 개발된 광섬유 바이오센서의 신호의 분석과 최적설계를 위하여 센서에 사용되어진 AChE효소(acetylcholinesterase)의 반응, 반응기 내의 유체거동 및 물질전달현상의 해석이 필요하다. 사용되어진 센서의 반응기 부분을 해석하고 재설계하기 위하여 효소 반응을 연구하고, 이동현상학적으로 유체 및 물질확산 현상을 해석하여 반응기 모델을 성립하였다. 사용되어진 유기인 화합물에 의해 저해되는 AChE효소의 측정범위인 0-2 ppm 사이에서 저해반응을 실험하였으며, 비가역 저해 효소 반응식을 제안하였다. 반응기를 두상 즉 벌크상과 효소층으로 나누어 유체거동을 해석하였으며, 고정화겔 내의 확산의 영향을 조사하였다. 반응식, 유체거동식 및 확산식을 연계하여 세워진 반응기 전체모델을 제시하였고, 이를 이용하여 신호를 해석하였다. 제시된 모델을 이용하여 효소량, 효소층의 두께의 증가에 따른 센서 신호량의 민감도를 전산모사하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제16권3호
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• pp.389-393
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• 2003

Present study investigate the effect of enzyme supplementation, methods (applied to rumen or enzyme treated diet) compared with no enzyme diet, on rumen fermentation and apparent nutrient digestibility in a $3{\times}3$ Latin square design with three rumen cannulated Korean Native goats. In situ rumen degradation kinetics was studied in three rumen cannulated Holstein steers. Three diets were, no enzyme, 1% enzyme in rumen and 1% enzyme in diet. The enzyme was sprayed onto forage, and the forage: concentrate ratio was 30:70. Degradation kinetics was studied with three enzyme levels (0, 1 and 2%, w/w) and four pre-treatment times (0, 1, 12 and 24 h). Results suggested that enzyme application method did not affect rumen fermentation, ruminal enzyme activity and total tract apparent digestibility. Nutrient degradation rate and effective degradability of DM, NDF and ADF increased with increasing enzyme level and pre-treatment times. Degradation of nutrients was affected by enzymes levels or pre-treatment times. Therefore, it is probable that the improved degradation may be due to the supplemented exogenous hydrolytic enzymes under a certain condition.

• 한국포장학회지
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• 제21권1호
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• pp.1-10
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• 2015

Enzyme kinetics-based respiration model can be effectively used for estimating respiration rate in $O_2$ consumption and $CO_2$ production of fresh produce as a function of $O_2$ and $CO_2$ concentrations. Arrhenius equation can be applied to describe the temperature dependence of the respiration rate. Parameters of enzyme kinetics-based respiration model and activation energy of Arrhenius equation were compiled from analysis of literature data and closed system experiment. They enable to estimate the respiration rate for any modified atmosphere conditions at temperature of interest and thus can be used for design of modified atmosphere packaging of fresh produce.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1565-1568
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• 2009

Purified Helicobacter pylori urease displayed a sigmoid curve in the plot of velocity versus [S] at urea concentrations less than 0.1mM. Under conditions where preservatives, glycerol, or polyethylene glycol (PEG) were added to the enzyme reaction, the substrate hydrolysis was consistent with Michaelis-Menten kinetics, with a $K_m$ of $0.21\;{\pm}\;0.06\;mM$ and a $V_{max}$ of $1,200\;{\pm}\;300\;{\mu}mol\;min^{-1}\;mg^{-1}$. However, at saturating substrate concentrations, the kinetic parameters of H. pylori urease were unaffected by the presence of the preservatives, and enzyme catalysis conformed to Michaelis-Menten kinetics. The Hill coefficients of the enzyme-catalyzed urea hydrolysis in the presence and absence of PEG were 1 and 2, respectively. Based on these findings, we suggest that H. pylori urease may exist in aggregated and dissociated forms, each with intact function but differing kinetics that may be of importance in maximizing urea breakdown at varying urea concentrations in vivo.

• KSBB Journal
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• 제6권2호
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• pp.157-166
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• 1991

The structural properties of cellulose are significantly changed with the progress of hydrolysis reaction. The effects of changes on such properties of cellulosic substrate as crystallinity, amicessibility of enzyme to the active site of cellulose surface, and particle size on the kinetics of enzymatic hydrolysis have been studied. Among those physical studies, the apparent surface active site of cellulose particle was found to have the most significant effect on the hydrolysis kinetics. Based on the experimental results, the adsorption affinity of enzyme and hydrolysis rate were mainly influenced by the surface roughness of cellulose particle. The extent of accesssible active site may be expressed as the change of particle diameter. The Langmuir isotherm was proposed in terms of enzyme activity to explain the actual action of enzyme protein.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.925-928
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• 2012

The accurate expression for the steady-state velocity of an irreversible enzyme-catalyzed reaction obtained by Shin and co-workers (J. Chem. Phys. 2001, 115, 1455) is generalized to allow for the rebinding of the product. The amplitude of the power-law ($t^{-1/2}$) relaxation of the free- and bound-enzyme concentrations to steady-state values is expressed in terms of the steady-state velocity and the intrinsic (chemical) rate constants. This result is conjectured to be exact, even though our expression for the steady-state velocity in terms of microscopic parameters is only approximate.