1. Enzymes

2. What are Enzymes? Enzymes are proteins
Used by the cell to speed up reactions.
Are biological catalysts
Remain unchanged by the reaction
Are reusable

3. How do enzymes Work?
Enzymes work by weakening bonds which lowers activation energy

4. Enzymes
Enzymes are proteins with a 3 dimensional shape. Their specific shape determines the substrate that it works with. Substrates are the substances that the enzymes act upon.
Lipase acts on lipids.
Maltase acts on maltose.
Protease acts on proteins.
Substrates
Enzymes

5. Step by Step The substrate binds to the enzyme at the active site
Only certain substrates can fit the active site
Enzyme-substrate complex forms
Substrate reacts to form product
Product is released

6. (substrate begins reaction)
Substrate binds to the
enzyme at the
Active Site
Enzyme substrate
complex forms
(substrate begins reaction)
Product is released
Enzyme can be used
again

7. Enzymes
The rate of enzyme activity depends not only on its 3 dimensional shape, but it also depends on other factors.
temperature pH
concentration
inhibitors

8. Temperature Little activity at low temperature
Rate increases with temperature
Most active at optimum temperatures (usually 37°C in humans)
Enzymes denature (change shape) at high temperatures

9. Temperature What is the optimal temperature for enzyme A? ________
What is the optimal temperature for enzyme B? ________
Knowing that room temperature is approximately 22 degrees Celsius, which enzyme would work best in your body? __________
38oC
62oC A

10. pH Maximum activity at optimum pH Narrow range of activity
Most lose activity in low or high pH

11. pH What is the optimal pH for the enzyme found in your stomach ?
Gastric Protease
Intestinal Protease
What is the optimal pH for the enzyme found in your stomach ?
What is the optimal pH for the enzyme found in your intestine?
What organic substance are both of these enzymes digesting? 3
7.8
Proteins

12. Concentration
Increasing substrate concentration increases the rate of reaction
Maximum activity reached when all of
enzyme combines with substrate

13. Inhibitors Competitive inhibitor Substrate
Competitive: are chemicals that
resemble an enzyme’s normal substrate and compete with it for the active site.
Enzyme
Substrate
Competitive inhibitor

14. Inhibitors Substrate active site altered Enzyme Noncompetitive:
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

15. Competitive Inhibition Noncompetitive Inhibition
Inhibitors
Competitive Inhibition
Noncompetitive Inhibition