Lt 12 Cofactors and Inhibitors

Question 1

Is a cofactor a protein? What are the two types of cofactor?

Answer 1

Non-protein, inorganic metal ions and organic

Question 2

What are the two types of organic cofactors?

Answer 2

Co-enzymes, loosely associated and prosthetic, covalently attached

Question 3

What is the metabolism of a co-enzyme/prosthetic group compared to an enzyme substrate

Answer 3

Slowly degraded/long lived compared to substrate

Question 4

Where do coenzymes come from in our diet?

Answer 4

Vitamins

Question 5

Give an 3 examples of a irreversible enzyme inhibition; one good, one bad and one pseudo. How do they bond?

Answer 5

Rarely natural, sarin gas is bad, penicillin is good for us (bad for enzymes) and type of acetylcholine inhibitor is good for short term treatment of alzeimers

Covalent bonds!!!
IX
I  X
I   X
I      X
I\_\_ \_\_\_XXXXXXX\_\_\_\_\_\_\_\_\_

Question 6

What is the effect on Km and Vmax with competitive inhibitor?
Where does the inhibitor bind on the enzyme? Is it’s affinity higher or lower than the substrate?

Answer 6

Increase in Km
No effect on Vmax
Active site, with higher affinity

Question 7

What is the effect on Km and Vmax with non-competitive inhibitor?
Where does inhibitor bind?
What happens?
Does it prevent S from binding?

Answer 7

No effect on Km
Decrease in Vmax
Binds to allosteric binding site, not the active site but within cleft causing shape change
Doesn’t prevent S from binding but prevents reaction from proceeding

Question 8

What is the effect on Km and Vmax with uncompetitive inhibitor?
Where does inhibitor bind?
What happens? Can S bind?

Answer 8

Decrease of Km and Vmax
Binds to allosteric binding site, not the active site but within cleft causing shape change
Only binds to ES not E on it’s own, prevents reaction from proceeding