enzymes: remarkable biological catalysts jianing li chemistry department columbia university april...
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Enzymes: Remarkable Biological
CatalystsJianing Li
Chemistry DepartmentColumbia University
April 14th,2007
The activity of an enzyme is responsible for the glow of the luminescent jellyfish
Basic Concepts
Enzyme Substrate Active Site Cofactor and coenzyme Inhibitor
What is an enzyme?
The catalyst of biological systems The remarkable molecular device that dete
rmine the patterns of chemical reactions Catalytic power and specificity Mainly proteins, but ribozyme (RNA)
What are the characteristics of enzymes? Higher efficiency Milder conditions Greater reaction specificity Capacity for regulation
Factors influencing enzyme activity: ppHH, tempertemperatureature, concentrationconcentration of enzyme and substrate
Why highly efficient?
Catalytic power and specificity
Enzymes and Cofactors Most other enzymes are named for their s
ubstrates 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
Cofactor in an enzymeFrom www.psc.edu
Six major classes of enzymes
Oxidoreductases Transferases Hydrolases Lyases Isomerases Ligases
Active Sides
How does an Enzyme Work?
Lock-and–Key Model
Induce-Fit Model
Inhibitors
If you want to know more about enzymes: http://www.northland.cc.mn.us/biology1111/
animations/enzyme.swf http://ca.expasy.org/spdbv/text/getpc.com http://biochem.ucl.ac.uk/bsm/enzymes/ Biochemistry, 5th edition, Jeremy M. Berg e
tc.
Exercise:
Surf in an enzyme data base Find an example for each class of
enzyme Think about the PDB ID, Name, Class,
Reaction, Cofactor
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)
Question 1.1 Which statement is correct about
enzyme classification?a. Enzymes are usually classified on their
structures.b. Enzymes are usually classified on their
mechanismc. Enzymes are classified into 5 classesd. Enzymes are classified into 7 classesGo back
Question 1.2
Enzymes are sensitive to these following factors except:
a. pH valueb. Temperaturec. Concentration of enzyme and substrated. LightGo back
Question 1.3
The molecules which decrease the enzyme activity are called:
a. Activatorsb. Initiatorsc. Indicatorsd. InhibitorsGo back
Question 1.4
If we want to deactivate an enzyme, we do these except:
a. Increase the temperatureb. Add inhibitorsc. Remove the coenzymed. Add salt solutionGo back
Question 2.1
Which statement is not the character of enzyme?
a. High efficiencyb. Mild conditionc. Specificityd. Turnover the reactionGo back
Question 2.2
Enzymes don’t change quantitatively in the biochemical reactions, but they change in structures temporarily.
a. This statement is falseb. This statement is completely truec. This statement is only true partiallyGo back
Question 2.3
How do animals make light?a. They heat themselvesb. They eat special chemicals which can give off
lightc. They make light from an enzyme-catalyzed
reactiond. All are correctGo back
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?
a. Increase the temperatureb. Increase the external pressurec. Add enzymesd. Add inhibitorsGo back
Question 3.1
There are __ kinds of inhibitor(s)?
a. 6
b. 5
c. 2
d. 1
Go back
Question 3.2
Cofactors aren’t:a. Enzymes
b. Metal ions
c. Small molecules
d. Vitamins
Go back
Question 3.3
Which of the following statement is correct?
a. Enzymes are specificb. The “lock-key” model shows that a enzyme is
flexible in structure and change itself to accommodate the substrate
c. Enzymes don’t change activation energyGo back
Question 3.4
Which statement is nor correct?a. All the enzymes are proteins
b. Not all the enzymes are proteins
c. Most enzymes are proteins
d. No enzyme is protein
Go back