1. Chapter Three: Enzymes

2. Inhibition of Enzymes
Can be irreversible (metals) or reversible (product, substrate, salt, etc.)
Types of inhibition:
Competitive
Noncompetitive
Uncompetitive
Substrate Inhibition

3. Competitive Inhibition
Inhibitor is an analog of the substrate, and binds to the active site of the enzyme.

4. Mechanism of Competitive Inhibition
What assumption have we make in defining the parameters on the right?

5. Competitive Inhibition
Product formation rate is given by:
What is the magnitude of relative to and what will be the effect on v? How could you run a process to minimize the effects of this type of inhibition?

6. Competitive Inhibition
Vm is unchanged
1/Vm
-1/Km
-1/Km,app
1/[S]

7. Noncompetitive Inhibition
Inhibitor binds to the enzyme and/or enzyme-substrate complex, but not at the active site. However, the enzyme affinity for substrate is reduced.

8. Mechanism of Noncompetitive Inhibition

9. Noncompetitive Inhibition
Product formation rate is given by:
Question: What is the magnitude of Vm,app relative to Vm, and what will be the effect on v? How can you moderate the effects of this type of inhibition.

10. Noncompetitive Inhibition
1/Vm,app
1/Vm
-1/Km
1/[S]
Km is unchanged

11. Uncompetitive Inhibition
Inhibitor binds only to ES complex, and not to E alone.

12. Uncompetitive Inhibition
Rate is given by:
What is the magnitude of Vm,app relative to Vm? What is the magnitude of relative to ?

13. Uncompetitive Inhibition
1/Vm,app
1/Vm
-1/Km
1/[S]
-1/Km,app

14. Substrate Inhibition
Substrate binds to ES complex. 14

15. Substrate Inhibition No substrate inhibition v Substrate inhibition S
The maximum substrate concentration resulting in maximum reaction rate is:

16. Summary of Enzyme Inhibition16

17. Example 3.2 17

18. Example 3.2 18

19. Example 3.2 19

20. Example 3.3 20

21. Example 3.3 21