Enzyme Inhibitors Flashcards
Which inhibitor:
- has no effect on Vmax
- increases Km
Competitive
Binds to active site of enzyme
Which inhibitor:
- decreases Vmax
- decreases Km
- Binds enzyme-substrate complex, but not the enzyme
Uncompetitive
Which inhibitor:
- decreases Vmax
- decreases Km
- Binds enzyme-substrate complex and the enzyme
Mixed
Which inhibitor:
- decreases Vmax
- has no effect on Km
Non-competitive
Which type of inhibitor might be prevented from binding to an enzyme if the substrate gets there first?
Competitive
Which type of inhibitor can bind to the enzyme at the same time as the substrate?
Mixed (including non-competitive)
If a mixed inhibitor has a competitive component that is stronger than the uncompetitive component, what is the effect on Vmax?
Decreases.
Although Km is affected by the strength of the components, Vmax always decreases with mixed inhibitors.
If a mixed inhibitor has a competitive component that is stronger than the uncompetitive component, what is the effect on Km?
Increases
If a mixed inhibitor has a uncompetitive component that is stronger than the competitive component, what is the effect on Km?
Decreases
If the competitive and uncompetitive components of a mixed inhibitor are of equal strength, what is the effect on Vmax and Km?
Vmax decreases
Km stays the same
This scenario describes a non-competitive inhibitor.
Where can a non-competitive inhibitor bind?
Either the free enzyme or the enzyme-substrate complex. It has equal affinity for both.
You add an unknown inhibitor to a reaction and Vmax remains unchanged. What class of inhibitor did you add?
A) Competitive
B) Uncompetitive
C) Mixed
D) Not enough info to tell
Competitive
You add an unknown inhibitor to a reaction and Vmax decreases. What class of inhibitor did you add?
A) Competitive
B) Uncompetitive
C) Mixed
D) Not enough info to tell
D) Not enough info to tell
It could be B or C, but option A is ruled out because competitive inhibitors have no effect on Vmax
You add an unknown inhibitor to a reaction and Km remains unchanged. What class of inhibitor did you add?
A) Competitive
B) Uncompetitive
C) Mixed
D) None of these
C) Mixed
It would be a non-competitive inhibitor, which is a type of mixed inhibitor that has equally match competitive and uncompetitive components.
