1. ENZYMES

2. Control METABOLISM
Metabolic reactions can be controlled and sped up by enzymes

3. metabolic reactions would be too slow to occur if no enzymes were present!
End in “ase”

4. Properties of Enzymes
Proteins
Catalysts
Reusable

5. Properties of Enzymes 4. Substrate specific
5. Sensitive to temperature
6. Sensitive to pH

6. Enzymes Remain Unchanged!
Enzymes are not used up; Reaction ends when there is NO MORE SUBSTRATE!!
Before
After

7. Mechanism of Enzyme Action
THE ACTIVE SITE is the place where the substrate binds with the enzyme
substrate
substrate
enzyme
active site

8. Action of Enzyme in Synthesis (TO MAKE)
enzyme-substrate complex
substrate
Product and
substrate
enzyme

9. Action of Enzyme in Decomposition (TO BREAK DOWN)
enzyme-substrate complex
product
substrate
enzyme

10. Lock and Key Hypothesis
Enzyme
Substrate

11. Lock and Key Hypothesis
SHAPES DON’T MATCH

12. Lock & Key Model ONE enzyme for every substrate Unique fit Enzyme

13. Enzymes are Temperature Dependent…...
Most work BEST at body temperature
37oC
DENATURE (change shape) at high temperatures
Inactive (doesn’t work that well) at LOW temperature

14. What is the optimum temperature for this enzyme?
How do you know?

15. What is pH?
Used to determine the acidity or alkalinity (base) of a solution on a scale on which 7 is neutral, lower values are more acid, and higher values more alkaline (basic)

17. Effect of pH on Enzyme Activity
-If pH of the substrate is higher or lower than optimum pH (highest enzyme activity) denaturation happens; enzyme becomes ineffective.
-Different enzymes may have different optimum pH’s

18. What pH does pepsin work best?
What pH does pancreatic lipase work?