Lecture 12 Flashcards
What do enzymes do
Lower the activation energy
Stabilize the transition state
What do enzymes not do
Change the (triangle)G of the reaction Irreversibly change shape
A catalyst is something that
Increases the rate of a reaction but does not undergo any permanent chemical change as a result
Change in S positive/negative/0
Positive- Increase in disorder
Negative- Decrease in disorder
0- No change in disorder
Change in G positive/negative/0
Positive- Endergonic, unfavorable reaction
Negative- Exergonic, favorable reaction
0- Equilibrium
Change in H positive/negative/0
Positive- Energy is released from the system
Negative- Energy is added to the system
0- Closed system
How can we speed up a reaction
Raise the temperature
Stabilize the transition state (using enzyme)
Induced fit model of catalysis
When a substrate binds, the enzyme changes shape so that the substrate is forced into the transition state
Catalysis is achieved through
Substrate orientation
Straining substrate bonds
Creating favorable microenvironment
Covalent/noncovalent interactions b/w substrate and enzyme
Covalent catalysis
Enzyme covalently binds the transition state (electrons transfer)
Acid-base catalysis
Partial proton transfer to the substrate
Approximation catalysis/Entropy reduction
Proper spatial orientation and close contact of the reactant molecules must occur for reaction to proceed I
-If both pieces of puzzle can be captured and held in proper orientation (by enzyme) reaction is more likely to occur
Electrostatic catalysis
Stabilization of unfavorable charges on the transition state by polarizable side chains in the enzyme and/or metal ions
What type of enzymes are chymotrypsin and carbonic anhydrase
Hydrolases
What is the problem with the reactions the catalyze
Chymotrypsin- reaction is too slow without it
Carbonic anhydrase- reaction isn’t fast enough without it
