1. Enzymes: Remarkable Biological Catalysts
Jianing Li
Chemistry Department
Columbia University
April 14th,2007

2. The activity of an enzyme is responsible for the glow of the luminescent jellyfish

3. Basic Concepts Enzyme Substrate Active Site Cofactor and coenzyme
Inhibitor

4. What is an enzyme? The catalyst of biological systems
The remarkable molecular device that determine the patterns of chemical reactions
Catalytic power and specificity
Mainly proteins, but ribozyme (RNA)

5. What are the characteristics of enzymes?
Higher efficiency
Milder conditions
Greater reaction specificity
Capacity for regulation
Factors influencing enzyme activity: pH, temperature, concentration of enzyme and substrate

6. Why highly efficient?

7. Catalytic power and specificity

8. Enzymes and Cofactors
Most other enzymes are named for their substrates and for the reactions that they catalyze, with the suffix "ase" added. (ATPase )
Many enzymes require cofactors for activity
Cofactors are small molecules or metal ions
Vitamins

9. Cofactor in an enzyme From www.psc.edu

11. Six major classes of enzymes
Oxidoreductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases

12. Active Sides

13. How does an Enzyme Work?

14. Lock-and–Key Model

15. Induce-Fit Model

16. Inhibitors

17. If you want to know more about enzymes:
Biochemistry, 5th edition, Jeremy M. Berg etc.

20. Exercise: Surf in an enzyme data base
Find an example for each class of enzyme
Think about the PDB ID, Name, Class, Reaction, Cofactor

21. Let’s play a game Questions Number 1. Hard (20 credits each)
(1.1) (1.2) (1.3) (1.4)
2. Medium
(15 credits each)
(2.1) (2.2) (2.3) (2.4)
3. Easy
(10 credit each)
(3.1) (3.2) (3.3) (3.4)

22. Question 1.1 Which statement is correct about enzyme classification?
Enzymes are usually classified on their structures.
Enzymes are usually classified on their mechanism
Enzymes are classified into 5 classes
Enzymes are classified into 7 classes
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23. Question 1.2 Enzymes are sensitive to these following factors except:
pH value
Temperature
Concentration of enzyme and substrate
Light
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24. Question 1.3
The molecules which decrease the enzyme activity are called:
Activators
Initiators
Indicators
Inhibitors
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25. Question 1.4 If we want to deactivate an enzyme, we do these except:
Increase the temperature
Add inhibitors
Remove the coenzyme
Add salt solution
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26. Question 2.1 Which statement is not the character of enzyme?
High efficiency
Mild condition
Specificity
Turnover the reaction
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27. Question 2.2
Enzymes don’t change quantitatively in the biochemical reactions, but they change in structures temporarily.
This statement is false
This statement is completely true
This statement is only true partially
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28. Question 2.3 How do animals make light? They heat themselves
They eat special chemicals which can give off light
They make light from an enzyme-catalyzed reaction
All are correct
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29. Question 2.4
If you are going to do an experiment, but it is very slow at room temperature. Which way can speed it up most?
Increase the temperature
Increase the external pressure
Add enzymes
Add inhibitors
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30. Question 3.1
There are __ kinds of inhibitor(s)? 6 5 2 1
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31. Question 3.2 Cofactors aren’t: Enzymes Metal ions Small molecules
Vitamins
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32. Question 3.3 Which of the following statement is correct?
Enzymes are specific
The “lock-key” model shows that a enzyme is flexible in structure and change itself to accommodate the substrate
Enzymes don’t change activation energy
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33. Question 3.4 Which statement is nor correct?
All the enzymes are proteins
Not all the enzymes are proteins
Most enzymes are proteins
No enzyme is protein
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