1. Enzymes
Mr. Spoor
Biology 1

2. What Are Enzymes? Most enzymes are Proteins
Act as Catalyst to accelerates a reaction
Not permanently changed in the process

3. Enzymes Are specific for what they will catalyze Are Reusable
End in –ase
-Amylase
-Lactase
-Sucrase
-Maltase
-Pepsin (for proteins)

4. How do enzymes Work?
Enzymes work by weakening bonds which lowers activation energy, and speeds up reactions.

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

7. Enzyme-Substrate Complex
The substance (reactant) an enzyme acts on is the substrate
Enzyme
Joins
Substrate

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

9. Lock and Key Hypothesis
Enzymes and substrates fit together like a lock and key.
-The substrate is like the key, and has an exact shape match for the enzyme, which is like a lock.
-one enzyme, one substrate.

10. Induced Fit A change in the shape of an enzyme’s active site
Induced by the substrate

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

12. What Affects Enzyme Activity?
Four factors:
1. Temperature
2. pH
3. Substrate Concentration
4. Inhibitors

13. What Affects Enzyme Activity?
1. Extreme Temperature are the most dangerous
- high temps may denature (unfold) the enzyme.
2. pH (most like pH near neutral)
3. Substrate concentration (The more you have, the faster it reacts, to a point where all enzymes are “full”)

14. What is the optimal pH for gastric protease to function?
….intestinal protease?
Within which pH range will both enzymes function?

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

16. Inhibitors b. Noncompetitive inhibitors:
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
Noncompetitive
Inhibitor
Substrate
active site
altered