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Question 1

Which of the following terms best describes a drug that binds to an active site and inhibits the enzyme, and where inhibition decreases when substrate concentration is increased?

a) allosteric inhibitor

b) irreversible inhibitor

c) reversible inhibitor

d) suicide substrate

Question 2

Which of the following terms best describes a drug which inhibits the enzyme, but binds to a binding site other than the active site?

a) allosteric inhibitor

b) irreversible inhibitor

c) reversible inhibitor

d) suicide substrate

Question 3

Which of the following is not true of transition-state analogues?

a) They mimic the transition state of an enzyme-catalysed reaction.

b) They react irreversibly with the enzyme.

c) They are bound more strongly than the substrate or the product.

d) They require the presence of a stable functional group to mimic the functionality present in the transition state.

Question 4

Which of the following is not true of suicide substrates?

a) They are activated by the enzyme-catalysed reaction mechanism.

b) They react irreversibly with the enzyme.

c) They form a covalent bond with the active site once activated.

d) They self destruct as a result of an enzyme-catalysed reaction.

Question 5

Which enzyme inhibitors represent the most common used clinical agents?

a) Reversible inhibitors

b) Irreversible inhibitors

c) Suicide substrates

d) Transition-state inhibitors

Question 6

Which of the following agents act as irreversible inhibitors?

a) sulfonamides

b) penicilllins

c) statins

d) protease inhibitors

Question 7

Which of the following drugs can be classed as a suicide substrate?

a) Orlistat

b) 6-Mercaptopurine

c) Aliskiren

d) Clavulanic acid

Question 8

Which of the following is not used as a measure of enzyme activity?

a) EC₅₀

b) K_i

c) IC₅₀

d) Log P

Question 9

Which of the following amino acids would be prone to a reaction with an irreversible inhibitor?

a) phenylalanine

b) serine

c) valine

d) alanine

Question 10

Which of the following amino acids would be most prone to a reaction with an irreversible inhibitor?

a) tyrosine

b) threonine

c) histidine

d) lysine

Oxford University Press, Online Resource Centre, Chapter 07.

Chapter 07

Instructions