Enzymes are proteins that act as catalysts to speed up chemical reactions by lowering their activation energy. They work through a lock-and-key mechanism where the enzyme and substrate physically fit together. This binding allows the enzyme to facilitate the reaction. Enzyme function can be inhibited through competitive inhibitors, which bind to the active site, or noncompetitive inhibitors, which induce a conformational change in the enzyme preventing substrate binding. Environmental factors like temperature, pH, and salt concentration can also impact an enzyme's activity by causing it to denature.

1. Enzymes

2. EnzymesEnzymes are special proteinsthat help control chemical reactionsby acting as catalysts.Catalysts can speed up some reactions by more than a billion fold.

3. 3. How they workEnzymes work by a physical fit (Lock and Key) between the enzyme and the substrate.When connected the enzyme lowers the activation energy needed for the chemical reaction.

6. 4. Draw the activation energy graph:

7. 5. InhibitionCertain substances can inhibit enzyme function.Competitive inhibitors: Get in the way…they “fit” into the active site.

8. 5. Inhibitionc. Noncompetitive (Allosteric) inhibitors: Change the shape of the enzyme so the substrate(s) no longer fit.SubstrateEnzymeNC InhibitorEnzyme

9. CompetitiveInhibition (DRAW this!)

10. Non-Competitive (Allosteric) Inhibition (DRAW this!)

11. 6. Environmental FactorsEnvironmental Factors can affect enzymes activity.TemperaturepHSaltMore…Really cold…slows down enzymesToo hot, too salty, pH…DENATURE (unfold, change shape)Denatured protein

12. Questions???Quick review:What type of macromolecule are enzymes?What is the “lock-and-key” model mean?How do enzymes speed up chemical reactions?What are the two types of competitors?How do they work?What factors can affect enzyme activity?