Lecture 23- enzyme inhibition

Question 1

Inhibition of monomeric enzymes

Answer 1

Can affect enzyme activity by binding to active site
Works by decreasing reaction velocity

Question 2

Why is it useful to understand and classify inhibitors?

Answer 2

Insight into catalytic mechanisms
Insight into metabolic control

Question 3

Reversible inhibitors

Answer 3

Can be removed by dialysis
Not covalently bonded

Question 4

Competitive inhibition

Answer 4

Competes with substrate at substrate recognition site
Similar structural analog
Occupies active site
Can be overcome by increasing substrate conc.
Increase Km, no effect on Vmax

Question 5

Ki

Answer 5

The dissociation constant for inhibitor binding
Lower Ki= stronger inhibitor

Question 6

Non-competitive inhibition

Answer 6

Doesn’t compete with substrate for binding site
reduces activity of the enzyme
Lowers Vmax as it lowers [active enzyme]
Km not affected as they don’t interfere with E to S binding

Question 7

Uncompetitive inhibition

Answer 7

Only binds to ES complexes not free enzymes
Binding of E and S reveals an additional binding site
Vmax decreased
Km decreased
inhibition can’t be overcome by [S]