1. Enzymes

2. 2 What Are Enzymes? Proteins (Most enzymes are Proteins (tertiary and quaternary structures) CatalystAct as Catalyst to accelerate a reaction Create a new reaction pathway “a short cut” Not permanentlyNot permanently changed in the process

3. 3Enzymes catalyzeAre specific for what they will catalyze ReusableAre Reusable aseEnd in –ase-Sucrase-Lactase-Maltase

4. 4 How do enzymes Work? weakening bonds which lowers activation energy Enzymes work by weakening bonds which lowers activation energy

6. 6Enzymes Free Energy Progress of the reaction Reactants Products Free energy of activation Without Enzyme With Enzyme

7. 7 Enzyme-Substrate Complex substance enzyme substrate The substance (reactant) an enzyme acts on is the substrate Enzymes are specific to their substrate Enzyme Substrate Joins

8. 8 Active Site Active Site restricted region enzyme bindssubstrateA restricted region of an enzyme molecule which binds to the substrate. Enzyme Substrate Active Site

9. The Lock and Key Hypothesis  Fit between the substrate and the active site of the enzyme is exact  Like a key fits into a lock very precisely  The key is analogous to the substrate and the enzyme is analogous to the lock.  Temporary structure called the enzyme-substrate complex formed  Products have a different shape from the substrate  Once formed, they are released from the active site  Leaving it free to become attached to another substrate

10. The Lock and Key Hypothesis Enzyme may be used again Enzyme- substrate complex E S P E E P Reaction coordinate

11. 11 Induced Fit changeconfiguration enzyme’s active siteA change in the configuration of an enzyme’s active site (H+ and ionic bonds are involved). Inducedsubstrate.Induced by the substrate. Enzyme Active Site substrate induced fit

12. Factors affecting Enzymes Three factors: 1.Environmental Conditions 2.Cofactors and Coenzymes 3.Enzyme Inhibitors

13. 1. Environmental Conditions 1. Extreme Temperature are the most dangerous 1. Extreme Temperature are the most dangerous - high temps denature (unfold) enzyme. - high temps may denature (unfold) the enzyme. 2.pH (most like 6 - 8 pH near neutral) 3.Ionic concentration (salt ions)

14. 2. Cofactors and Coenzymes Inorganic substances (zinc, iron) vitamins enzymatic activity Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes needed for proper enzymatic activity.Example: Iron quaternary structure-hemoglobin pick up oxygen. Iron must be present in the quaternary structure - hemoglobin in order for it to pick up oxygen.

15. 15 Two examples of Enzyme Inhibitors Competitive inhibitors: resemble enzyme’s normal substrate competeactive site Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Competitive inhibitor Substrate

16. 16 The effect of enzyme inhibition Noncompetitive inhibitors: do not enter the active sitebind to another part enzymeenzyme change its shape alters the active site Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site. Enzyme active site altered Noncompetitive Inhibitor Substrate