MCBM 1- (6) Enzyme, Kinetics, and
Regulation with Complete Questions
and Answers 100% Correct
What is kcat? What is a holoenzyme? - ANSWER - Kcat=overall rate of an enzyme, catalytic
efficiencies.
Holoenzyme (active) is an inactive apoenzyme with non-protein components. (look at the
picture)
Discuss enzyme-substrate specificity. What is the lock and key vs. induced fit model? -
ANSWER - Induced fit: enzyme changes after substrate binds to make it fit more perfectly.
Discuss energy implications of enzymes. Does it change the activation energy or free energy of
the overall reaction? - ANSWER - Activation energy is lowered with enzyme activity, overall
energy reaction stays the same.
Enzyme stabilizes the enzyme transition state complex, lowers the energy of the transition state.
What are the two ways you can accelerate biological reactions? - ANSWER - 1) Stabilize the
transition state, NOT the substrate. If you stabilize the transition state, you lower the activation
energy. This will accelerate the rxn.
2) Provide a catalytic group. This makes rxn go fast!
What are the 3 things that impact enzyme catalytic rate? - ANSWER - More substrate=higher
rxn rate
What is competitive inhibition? Is it competing for the same or different active site? What is the
change in Km or Vmax? - ANSWER -
Why is the change in Km an apparent change and not an actual change? - ANSWER - The
affinity for the substrate is the same, it's just that other molecules are taking up its spot.
Regulation with Complete Questions
and Answers 100% Correct
What is kcat? What is a holoenzyme? - ANSWER - Kcat=overall rate of an enzyme, catalytic
efficiencies.
Holoenzyme (active) is an inactive apoenzyme with non-protein components. (look at the
picture)
Discuss enzyme-substrate specificity. What is the lock and key vs. induced fit model? -
ANSWER - Induced fit: enzyme changes after substrate binds to make it fit more perfectly.
Discuss energy implications of enzymes. Does it change the activation energy or free energy of
the overall reaction? - ANSWER - Activation energy is lowered with enzyme activity, overall
energy reaction stays the same.
Enzyme stabilizes the enzyme transition state complex, lowers the energy of the transition state.
What are the two ways you can accelerate biological reactions? - ANSWER - 1) Stabilize the
transition state, NOT the substrate. If you stabilize the transition state, you lower the activation
energy. This will accelerate the rxn.
2) Provide a catalytic group. This makes rxn go fast!
What are the 3 things that impact enzyme catalytic rate? - ANSWER - More substrate=higher
rxn rate
What is competitive inhibition? Is it competing for the same or different active site? What is the
change in Km or Vmax? - ANSWER -
Why is the change in Km an apparent change and not an actual change? - ANSWER - The
affinity for the substrate is the same, it's just that other molecules are taking up its spot.
