Presentation on theme: "Slide 1 of 50 Enzymes Enzymes are biological catalysts Proteins Catalyst Lower activation energy Increases the rate of the reaction Affects."— Presentation transcript:
Slide 1 of 50 Enzymes Enzymes are biological catalysts Proteins Catalyst Lower activation energy Increases the rate of the reaction Affects nothing other than the reaction rate Does NOT affect the free energy of the reaction
Slide 7 of 50 Enzyme Activity is affected by… Concentration of substrate Concentration of enzyme If enzyme is saturated, then rate is determined by enzyme’s rate for converting substrate to product Cofactors / Coenzymes presence Presence of Inhibitors
Slide 14 of 50 Questions 1. How does competitive inhibition differ from noncompetitive inhibition? 2. How does a cofactor differ from a coenzyme? 3. Name 3 things that affect enzyme activity? 4. What does an enzyme do?
Slide 15 of 50 Pathway Regulation 2 main ways to regulate metabolic pathways: 1. Switching on/off genes 2. Regulating enzyme activity
Slide 16 of 50 Allosteric Regulation Allosteric – specific binding site NOT the active site!! Can be inhibition or activation Allosteric molecule binds to a site other than the active site Allosteric molecule binding enzyme shape change Change in enzyme shape active site shape change Structural change = Functional change
Slide 18 of 50 Allosteric Regulation Enzyme units oscillate between two conformational sites One is catalytically active, the other is inactive Regulatory site Called allosteric site Activator or inhibitor binds and stabilizes the conformational form Usually an activator or inhibitor affects all active sites
Slide 19 of 50 Cooperativity When a substrate molecule causes an induced fit in one active site triggers the same change in all subunits of the enzyme Amplifies the response of enzymes to substrates Primes the enzyme to accept more substrate
Slide 20 of 50 Feedback Inhibition A metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway An example of allosteric inhibition Increases efficiency of a pathway Pathway is turned off when product accumulates
Slide 22 of 50 Final Questions 1. What happens to an enzyme in a chm rxn? 2. How does allosteric inhibition differ from noncompetitive inhibition? 3. What is the allosteric site? 4. How does cooperativity differ from allosteric activation? 5. What is the most effective method of pathway regulation?