1. Enzymes

2. What Are Enzymes?
Enzymes are Proteins that act as a Catalyst to accelerate (help start) a chemical reaction.

3. Enzymes
Each enzyme is made to work with only one chemical called its substrate.
A substrate and its enzyme fit together like a lock and key
After the reaction, only the substrate is chemically changed. The enzyme can be reused.
Enzyme names usually end in –ase. Example: Lactase

4. How do enzymes Work? Every reaction requires a “starting energy”
Enzymes work by weakening bonds and lowering that activation energy, so the reaction can happen faster/easier

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

6. Enzyme-Substrate Complex
The substrate bonds to the enzyme at a special area called the “active site”
Enzyme
Joins
Substrate

7. Active Site
The substrate bonds to the enzyme at a special area called the “active site”
Active Site
Enzyme
Substrate

8. Enzyme Activity
Once the substrate bonds, the enzyme changes shape to start the reaction

9. Enzyme Activity
The substrate is chemically changed by the enzyme and then released. After which, the enzyme returns to normal. The enzyme can now move on to a new substrate.
Enzyme
Active Site
substrate
induced fit

10. What Affects Enzyme Activity?
Every enzyme has its own specific temperature and pH that is optimal (best). Changes in these optimal conditions can slow down or denature (destroy) enzymes
Three factors that affect enzyme activity:
1. Environmental Conditions
2. Cofactors and Coenzymes
3. Enzyme Inhibitors

11. 1. Environmental Conditions
1. Extreme temperatures can damage or denature enzymes
2. Strong changes in pH (in either direction) can also denature enzymes
3. Too many ions (salts) can also denature enzymes.

12. 2. Cofactors and Coenzymes
Some enzymes work with partners or helpers
Inorganic substances (zinc, iron) and vitamins are sometimes needed for proper enzymatic activity.
Example:
Iron must be present in the protein - hemoglobin in order for it to pick up oxygen. Without Iron, it doesn’t work.

13. Enzyme Inhibitors
- Inhibitors are chemicals that slow down or block an enzyme from working. This helps your body turn enzymes on and off when you need to.
Enzyme
Substrate
inhibitor