2.4.7 Enzyme Activity: Enzyme Inhibitors

Question 1

What is a competitive inhibitor?

Answer 1

• Reversible inhibitor
• Similar shape to substrate
• So compete with substrate for active site

Question 2

What is a non-competitive inhibitor?

Answer 2

• Reversible inhibitor
• Bind to enzyme at alternate active site
• Conformational change occurs
• Altering shape of active site at which substrate is meant to form

Question 3

How can reversible inhibitors control metabolic reactions?

Answer 3

• End product inhibition
• Non-competitive inhibitor
• Enzyme’s active site changes so enzyme-substrate complexes stop forming
• End product detaches from enzyme and used somewhere else so active site reforms and enzyme returns to its active state
• So as product levels fall, enzyme begins to catalyse reactions once again, in a continuous feedback look

Question 3

What are non-reversible inhibitors?

Answer 3

• Inhibitors that form covalent bonds with enzymes
• Inhibiting them permanently
• Enzyme is completely inactivated
• Only way to counter it is to produce more of the enzyme but thats slow (whole Proteinsynthesis cycle)

Question 4

Examples of bad irreversible inhibitors?

Answer 4

• Cyanide (cytochrome oxidase in aerobic respiration)
• Lead (haemoglobin)
• Mercury

Question 4

Use of irreversible inhibitors in medicine?

Answer 4

Question 5

Rate of reaction graphs for enzyme activity

Answer 5