Enzymes

Enzymes

1. Enzymes are special proteins that help control chemical reactions by acting as catalysts.

2. Catalysts can speed up some reactions by more than a billion fold.

3. How they work

a. Enzymes work by a physical fit (Lock and Key) between the enzyme and the substrate.

b. When connected the enzyme lowers the activation energy needed for the chemical reaction.

4. Draw the activation energy graph:

5. Inhibition

a. Certain substances can inhibit enzyme function.

b. Competitive inhibitors: Get in the way…they “fit” into the active site.

5. Inhibition

c. Noncompetitive (Allosteric) inhibitors: Change the shape of the enzyme so the substrate(s) no longer fit.

Enzyme

Substrate

NC Inhibitor

Enzyme

Competitive Inhibition (DRAW this!)

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

6. Environmental Factors

a. Environmental Factors can affect enzymes activity.

I. Temperature

II. pH

III. Salt

IV. More…

b. Really cold…slows down enzymes

c. Too hot, too salty, pH…DENATURE (unfold, change shape)

Denatured protein

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?