Enzymes:%20Remarkable%20Biological%20Catalysts

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 enzymeFrom www.psc.edu
10
(No Transcript)
11
Six major classes of enzymes

• Oxidoreductases
• Transferases
• Hydrolases
• Lyases
• Isomerases
• Ligases

12
Active Sides
13
How does an Enzyme Work?
14
Lock-andKey Model
15
Induce-Fit Model
16
Inhibitors
17
If you want to know more about enzymes

• http//www.northland.cc.mn.us/biology1111/animatio
  ns/enzyme.swf
• http//ca.expasy.org/spdbv/text/getpc.com
• http//biochem.ucl.ac.uk/bsm/enzymes/
• Biochemistry, 5th edition, Jeremy M. Berg etc.

18
(No Transcript)
19
(No Transcript)
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
Lets 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
• Go back

23
Question 1.2

• Enzymes are sensitive to these following factors
  except
• pH value
• Temperature
• Concentration of enzyme and substrate
• Light
• Go back

24
Question 1.3

• The molecules which decrease the enzyme activity
  are called
• Activators
• Initiators
• Indicators
• Inhibitors
• Go back

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
• Go back

26
Question 2.1

• Which statement is not the character of enzyme?
• High efficiency
• Mild condition
• Specificity
• Turnover the reaction
• Go back

27
Question 2.2

• Enzymes dont 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
• Go back

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
• Go back

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
• Go back

30
Question 3.1

• There are __ kinds of inhibitor(s)?
• 6
• 5
• 2
• 1
• Go back

31
Question 3.2

• Cofactors arent
• Enzymes
• Metal ions
• Small molecules
• Vitamins
• Go back

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 dont change activation energy
• Go back

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
• Go back