Enzymes PDF

Enzymes Caner GEYİK, PhD [email protected]  2 Learning Objectives Describe enzymes and their common properties List the enzyme classifications in correct order Describe the factors that change enzyme activity Explain the rel...

Enzymes Caner GEYİK, PhD [email protected]  2 Learning Objectives Describe enzymes and their common properties List the enzyme classifications in correct order Describe the factors that change enzyme activity Explain the relationship between Km and activity Explain the enzyme inhibition and inhibition types  3 Metabolic Reactions 4 5  6 Activation Energy A B C Activation Energy Energy which must be provided to system to result in Energy a chemical or nuclear reaction Reaction Progress  7 Activation Energy and Catalysts Catalysts A B C A substance, that increase reaction rate by decreasing activation energy They are not consumed in reaction Energy Reaction Progress  8 Enzymes Enzymes are biocatalysts that increase the reaction rate  9 Properties of Enzymes Most of the enzymes are proteins. Ribozymes (Catalytic RNA): Ribonucleic acid biocatalysts. Enzymes change the reaction rate (efficiency), not the reaction equilibrium! They have specificity for substrate and reaction.  10 Efficiency Enzyme-catalyzed reactions are highly efficient, proceeding from 103 to 108 times faster than uncatalyzed reactions. Carbonic anhydrase is one of the fastest known enzymes. Each enzyme molecule can hydrate 106 molecules of CO2 per second.  11 Specificity Reaction Specificity A given enzyme catalyzes spesific type of reaction. Substrate Specificity A given enzyme uses spesific molecule or chemically related molecules.  12 Enzyme Nomenclature: Classification 1. Oxidoreductases EC Number 2. Transferases 2 4 1 11 3. Hydrolases 4. Lyases 5. Izomerases 6. Ligases Class Serial 7. Translocases Subclass Sub subclass The International Union of Biochemistry and Molecular Biology  13 https://www.enzyme-database.org/class.php  14 Enzyme Structure Substrate Apoenzyme: Protein part Cofactor: Non-protein part Active Site Holoenzyme: Catalytically active form  15 Enzyme Structure: Active Site  16 Enzyme Activity Activity = Speed (V) Number of substrate molecules that is converted to product in given time UNIT Activity: enzyme activity that changes 1 µmol substrate in 1 minute under optimal conditions  17 Factors Effecting Enzyme Activity Enzyme concentration Substrate concentration Temperature pH Inhibitors  18 Enzyme concentration  19 Substrate concentration Reaction Rate Substrate Concentration  20 Temperature Optimum temperature: Temperature that enzyme show maximum activity Different for every enzyme Humans 35-40 °C Thermophilic bacteria 70 °C  21 pH Optimum pH: pH that enzyme show maximum activity Different for every enzyme  22 Inhibitors Any substance that can decrease the velocity of an enzyme- catalyzed reaction is called an inhibitor. 1. Reversible 2. Irreversible  23 Reversible Inhibition  24 Enzyme Kinetics and Km Reaction Rate Substrate Concentration  25 Enzyme Kinetics and Km Km ; reflects the affinity of the enzyme for the substrate. Small Km = High affinity Large Km = Low affinity  26 Km , A Clinical Example  27 Regulation of Enzyme Activity  28 Regulation of Enzyme Activity  29 Regulation of Enzyme Activity  30 Regulation of Enzyme Activity Cutting the edges  31 Regulation of Enzyme Activity Phosphorylation / Dephosphorylation  32 Regulation of Enzyme Activity Feed-back inhibition  33 Regulation of Enzyme Activity Feed-forward activation  34 Regulation of Enzyme Activity  35 Regulation of Enzyme Activity Enzymes that catalyze the same reaction but have different sequences.