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Enzymes: Remarkable Biological Catalysts. Jianing Li Chemistry Department Columbia 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.
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Enzymes: Remarkable Biological Catalysts Jianing Li Chemistry Department Columbia 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 determine 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: pH, temperature, concentration of enzyme and substrate
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
Six major classes of enzymes • Oxidoreductases • Transferases • Hydrolases • Lyases • Isomerases • Ligases
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 etc.
Exercise: • Surf in an enzyme data base • Find an example for each class of enzyme • Think about the PDB ID, Name, Class, Reaction, Cofactor
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
Question 1.2 • Enzymes are sensitive to these following factors except: • pH value • Temperature • Concentration of enzyme and substrate • Light Go back
Question 1.3 • The molecules which decrease the enzyme activity are called: • Activators • Initiators • Indicators • Inhibitors Go back
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
Question 2.1 • Which statement is not the character of enzyme? • High efficiency • Mild condition • Specificity • Turnover the reaction Go back
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 Go back
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
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
Question 3.1 • There are __ kinds of inhibitor(s)? • 6 • 5 • 2 • 1 Go back
Question 3.2 • Cofactors aren’t: • Enzymes • Metal ions • Small molecules • Vitamins Go back
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 Go back
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