ENZYMES

1. ENZYMES Biological Puzzle Pieces

2. REMEMBER: What is a Catalyst? • A chemical that increases the rate of chemical reactions without altering the products or being altered itself

3. A Little About Reactions… • Chemical reactions occur when molecules within a system collide • Adding thermal energy to a system increases kinetic energy • Thus, molecules move faster and increase chances of collision • CATALYSTS speed up reactions at LOW TEMPS, so additional energy is not needed!

4. ENZYMES • A protein catalyst that is found in LIVING THINGS. • Permit low-temperature reactions by reducing the amount of activation energy required. • Enzymes are denoted using “-ase” as their ending. • i.e. carbohydrases break down carbohydrates

5. How Do They Work? • ENZYMES work on SUBSTRATES like a “puzzle piece” • Each substrate combines with a specific enzyme • Upon combination, the substrate changes and creates a new product • Estimated 200,000 different reactions in your body, each using a specific enzyme/substrate

6. How Do They Work? • “ACTIVE SITE” is the area of the enzyme that joins with the substrate. Imagine it as the “dock” • This creates the “Enzyme-Substrate Complex”

7. Co-Stars • COFACTORS:an organic ion that helps an enzyme combine with a substrate molecule • COENZYME: an organic molecule synthesized from a vitamin that helps an enzyme combine with a substrate molecule.

8. FACTORS AFFECTING ENZYME REACTIONS

9. 1. pH • Certain enzymes function most effectively at specific pH ranges. • i.e. PEPSIN: enzyme found in the stomach, works best at a low pH (b/c stomach is an acidic environment) • i.e. TRYPSIN: enzyme found in the small intestine, works best at a high pH (b/c intestine is a basic area)

10. 2. Substrate Concentration • Because reactions happen due to collisions, higher numbers of substrates increase the likelihood of a collision between substrates and enzymes.

11. 3. Temperature • As stated earlier… • Higher Temp. = Faster Reactions • BUT!!... • Why do reaction rates in human cells peak at 37 degrees?

12. 3. Temperature Cont’d • At higher temperatures, proteins change shape or are denatured. • REMEMBER: Enzymes are PROTEINS • So, at certain temperatures, ENZYMES change their shape or are destroyed all together • This reduces the chance of enzyme-substrate combintation

13. 4. Competitive Inhibition • INHIBITORS are very similar in shape to substrates • Thus, they bond with enzymes before substrates have a chance, reducing the function of the enzyme.