1. Lecture 4 Enzymes

2. Proteins Catalyze all cellular reactions Enzymes are not changed by the reactions, and can be reused

3. Protein Shape Proteins need the proper shape to function Increased temperature, high or low pH, or certain solvents, cause the bonds within the protein to be broken Denatured protein: no longer functions

5. Enzymes Function by lowering the activation energy of a chemical reaction so it is more likely to occur Enzymes weaken chemical bonds in the substrate

7. Enzymes Very specific due to 3-D shape Contain an active site: region where a specific substrate binds Substrate: substance upon which an enzyme acts Enzyme + Substrate  Enzyme-Substrate complex Enzyme + Product

10. Cofactors and Coenzymes Some enzymes need help to build active site Cofactors: inorganic molecules that help build active site of enzyme Coenzymes: organic molecules that help build the active site

11. Figure 5.3

12. Enzymes Often Team Up in Metabolic Pathways –A metabolic pathway is a sequence of chemical reactions

13. Factors Influencing Enzymatic Activity Temperature: chemical reaction increases as temperature increases, up to a certain point pH: most enzymes has optimum pH Substrate concentration: Increase substrate amount, increases reaction rate Inhibition

14. Figure 5.5 - Overview

15. Enzyme Inhibition Competitive Inhibition: inhibitor competes with the substrate for the active site Non-Competitive inhibition: when inhibitor and substrate act at different sites on the enzyme Feedback Inhibition: inhibits an enzyme in the pathway so no product is available to feed the next reaction

16. Figure 5.7 - Overview

18. Figure 5.8

19. Classification of Enzymes

20. Classification- Based on where enzyme activity occurs Exoenzymes Endoenzymes