CHAPTER 2. ENZYMES ppt

1 CHAPTER 2. ENZYMES INTERNATIONAL UNIVERSITY SCHOOL OF BIOTECHNOLOGY BIOCHEMISTRY 2 Learning objectives 1. Comprehend how enzyme kinetics relates to the chemical kinetics presented in general chemistry courses. 2. Perceive how kinetic parameters are experimentally determined. 3. Learn the Michaelis–Menten equation and the meaning of K M and V max . 4. Understand the enzyme kinetics 3 Brief Content 1. WHAT IS ENZYME? 2. CLASSIFICATION OF ENZYME 3. PROPERTIES OF ENZYME 4. ENZYME KINETICS 5. CATALYSIS (assignment) 6. ENZYME REGULATION (assignment) 4 Detailed Content 1. WHAT IS ENZYME? 2. PROPERTIES OF ENZYME 3. CLASSIFICATION OF ENZYMES 4. ENZYME KINETICS Michaelis- Menten kinetics Lineweaver Burk plots Enzyme inhibition 5. CATALYSIS Catalytic mechanisms The role of cofactor in enzyme catalysis Effects of temperature and pH on enzyme-catalyzed reactions Detailed mechanisms of enzyme catalysis 6. ENZYME REGULATION Covalent modification Allosteric regulation 5 1. WHAT IS ENZYME?  The most important functions of enzyme is their role as catalyst. All enzymes were considered to be protein but some examples of RNA molecules can also be catalyst.  Living processes consists almost entirely of biochemical reactions. Without catalysts these reactions would not occur fast enough to sustain life. 6 How a biochemical reaction can happen?  A reaction happens need the energy to vibrate the molecules and the reactant concentration enough. The energy here is often provided by heat.  However, in living system, high temperature may harm the biological structure  Truly that the concentration in living system is very low. So living organisms solve these problems by using enzyme 7 Which properties help enzyme a biocatalyst 1. The rates of enzymatically catalyzed reactions are often phenomenally high 2. The enzyme are highly specific to the reaction 3. Enzyme has the complex structures so it can be regulated 8 2. PROPERTIES OF ENZYMES  The active site  Activation energy  Cofactor 9 3. CLASSIFICATION OF ENZYMES  There are the six major enzyme categories: 1. Oxidoreductases: Oxidoreductase catalyze oxidation-reduction reactions. Subclasses of this group include the dehydogenases, oxidases, oxygenases, reductases, peroxidase, and hydroxylases 10 2. Transferases Transferases catalyze reactions that involve the transfer of groups from one molecule to another such as amino, carboxyl, carbonyl, methyl, phosphoryl, and acyl (RC=O) and the enzyme names often go with trans such as transcarboxylase, transmethylase, and transaminases [...]... occur The kinetics of the reaction indicate how fast the reaction actually goes Most of the biological reactions that occur in the cells of living organisms are greatly sped up by protein catalysts called enzymes Recall that catalysts dramatically increase the rate of a reaction without affecting the equilibrium 15 16 Enzyme kinetics ELEMENTARY KINETICS Our first objective for this exercise is to show how... special case is much too limiting and rarely applies in biological and experimental systems Consequently, biochemists must use a different model to describe the kinetics of biological reactions catalyzed by enzymes 25 26 Enzyme kinetics 27 ENZYME KINETICS The kinetics of an enzyme-catalyzed reaction can be studied when the concentration of the enzyme is small compared to the concentration of the substrate... as the maximal velocity, or Vmax 29 30 Enzyme kinetics To account for this kinetic behavior caused by the substrate’s interaction with enzyme, the model for an enzyme-catalyzed reaction must include an enzymesubstrate complex, or ES complex The reaction scheme is shown here The rate constants k1 and k–1 are the forward and reverse rate constants for the formation of the ES complex, and k2 is the rate . 1 CHAPTER 2. ENZYMES INTERNATIONAL UNIVERSITY SCHOOL OF BIOTECHNOLOGY BIOCHEMISTRY 2 Learning objectives 1. Comprehend how enzyme kinetics. are often phenomenally high 2. The enzyme are highly specific to the reaction 3. Enzyme has the complex structures so it can be regulated 8 2. PROPERTIES OF ENZYMES  The active site  Activation. Hydrolases include the esterases, phosphatase, and peptidase 12 4. Lyases: Lyases catalyze reaction in which groups H 2 O, CO 2 , and NH 3 are removed to form double bond or are added to