logo in the name of god kinetics of enzyme & immobilized enzymes by sara madani
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- LOGO IN THE NAME OF GOD KINETICS OF ENZYME & IMMOBILIZED ENZYMES BY SARA MADANI
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- Contents Enzyme Immobilized Enzymes Kinetics of immobilized enzyme Enzyme kinetics Method of Immobilization
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- Introduction Enzymes are usually proteins of high molecular weight (15,000 < MW < several million daltons ) that act as catalysts. Enzymes are specific versatile, biological catalysts, resulting in much higher reaction rates as compared to chemically catalyzed reaction under ambient condition. Enzymes are substrate specific and are classified according to the reaction the catalyze.
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- Substrate & Enzyme The substrate is a relatively small molecule and fit into a certain region on the enzyme molecule, which is a much larger molecule. The simplest model describing this interaction is the lock-and-key model.
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- Immobilized Enzymes The restriction of enzyme mobility in a fixed space is known as enzyme immobilization.
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- Why Immobilization? ImmobilizationImmobilization Advantages Lower capital cost enzyme reutilization elimination of recovery & purification provide a better environment
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- METHODS OF IMMOBILIZATION D B C A Binding to Carriers Immobilization by binding Cross-linking Matrix Entrapment Membrane Enclosure Immobilization by Physical retention
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- Classification of enzyme immobilization method
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- Immobilized Enzyme Kinetics of Enzyme in Solution Enzyme Kinetics Kinetic of Immobilized Enzyme
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- Enzyme Kinetic Introduction A mathematical model of the kinetics of single- substrate-enzyme-catalyzed reaction was first developed by V. C. R. Henri and by L. Michaelli and M. L. Menten. Kinetics of simple enzyme-catalysed reaction are often referred to as Michaelis-Menten kinetics.
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- Mechanistic Models for Simple Enzyme Kinetics Two major approaches used in developing a rate expression for the enzyme catalyzed reactions are: rapid-equilibrium approach quasi-study-state approach.
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- Mechanistic Models for Simple Enzyme Kinetics The rate of product formation: The rate of variation of ES complex: The eqn on the enzyme yields: Both of them are the same in initial steps in deriving a rate expression.
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- The rapid equilibrium assumption Assuming a rapid equilibriume between the enzyme & Substrate to form an [ES] complex. The equilibriume constant is: For [ES]: Finaly: where
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- The quasi- steady-state assumption By applying this assumption to eqn 3 we find: Subs enzyme eqn in eqn 9 yields: Subs above eqn in to eqn 2 yields Where
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- Kinetic of Immobilized Enyme Many factors can cause the kinetic parameters of immobilized enzymes to differ from those of soluble enzymes. 2 Electrostatic and partitioing effects 3 Diffusional,or mass- transfer effect 1 Conformational effects This factors can be classified as follows
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- Effects Of the Electrostatic potential The equilibrium condition requires that the electrochemical potential of the hydrogen ions in the particle equals with bulk phase The distribution of the charged substrate between the particle and the bulk phase is then:
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- Assume that the reaction catalyzed by the immobilized enzyme obey Michaelis-Menten kinetics The rate of reaction expressed in terms of the local substrate concentration by: the apparent Michaelis-Menten of the immobilized enzyme is: Effects Of the Electrostatic potential
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- Effect of External Mass Transfer Uncharged Support Suppose the enzyme is immobilized to the surface of an nonporous particle The average flux of substrate to the fluid-solid interface can be written : At steady state, the enzymatic reaction rate must be exactly balanced by the rate of substrate transport to the catalyst surface ;therefore, This eqn can be cast into dimensionless form by introducing the following dimensionless variables
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- Thus we can write Where Da,an important dimensionless group known as the Damkhler numbers To determine the significant effect of external diffusion resistance on the rate of enzyme catalytic reaction rate we use Da. The physical interpretation: Effect of External Mass Transfer
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- When Da >> 1, the external diffusion rate is limiting; Da 100 the effects of external resistance are not significant Simultaneous External &Internal Mass-Transfer Resistances& Partitioning Effects
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- Reference  Shuler,ML. and Kargi, F.Bioprocess Engineering:Basic Concepts2 nd Edition, 2005.prentice-Hall Inc.  Harvey W.Blanch. And Douglas S. Clark.Biochemical Engineering1996,MARCEL DEKKER,INC., New York,USA.  http://www.wsu.edu/~jmlee/eBioCheSample.pdfhttp://www.wsu.edu/~jmlee/eBioCheSample.pdf http://www.cheric.org/ippage/e/ipdata/2004/05/file/e200405-1101.pdfhttp://www.cheric.org/ippage/e/ipdata/2004/05/file/e200405-1101.pdf Company Logo www.themegallery.com
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