ENZYME INHIBITION AND REGULATION

Question 1

a non-prescription drug irreversibly inhibits prostaglandins and thromboxane synthesis by inhibiting cyclooxygenase

Answer 1

ASPIRIN

Question 2

the inactive precursor of a proteolytic enzyme

Answer 2

zymogen or proenzyme

Question 3

Any substance that can diminish the velocity of an enzyme-catalyzed reaction

Answer 3

inhibitor

Question 4

regulated by molecules called effectors (also called modifiers) that bind noncovalently at a site other than the active site

Answer 4

Allosteric enzymes

Question 5

inhibitors bind to enzymes through covalent bonds

Answer 5

irreversible inhibitors

Question 6

Effectors that inhibit enzyme activity

Answer 6

negative effectors

Question 7

inhibitors typically bind to enzymes through noncovalent bonds, thus dilution of the enzyme–inhibitor complex results in dissociation of the reversibly bound inhibitor

Answer 7

Reversible inhibitors

Question 8

those that increase enzyme activity

Answer 8

positive effectors

Question 8

two most commonly encountered types of reversible inhibition

Answer 8

competitive
noncompetitive

Question 9

catalyzed by a family of enzymes called protein kinases that use adenosine triphosphate (ATP) as a phosphate donor

Answer 9

Phosphorylation

Question 10

This type of inhibition occurs when the inhibitor binds reversibly to the same site that the substrate would normally occupy and, therefore, competes with the substrate for that site

Answer 10

Competitive inhibition

Question 11

Phosphorylation reactions are catalyzed by a family of enzymes called

Answer 11

protein kinases

Question 12

an example of competitive inhibitor

Answer 12

STATIN DRUGS

Question 13

TRUE / FALSE:
Enzymes subject to regulation of synthesis are often those that are needed at only one stage of development or under selected physiologic conditions

Answer 13

TRUE

Question 14

structural analogs of the natural substrate for this enzyme, and compete effectively to inhibit HMG-CoA reductase

Answer 14

STATIN DRUGS

Question 15

regulating cellular enzyme activity based on the production of enzymes in an inactive form

Answer 15

Proteolytic enzyme and zymogen

Question 15

This type of inhibition is recognized by its characteristic effect on Vmax

Answer 15

Noncompetitive inhibition

Question 16

generated in an inactive form and then later, when they are needed, are converted to their active form

Answer 16

proteolytic enzymes

Question 17

occurs when the inhibitor and substrate bind at different sites on the enzyme

Answer 17

Noncompetitive inhibition

Question 18

an enzyme that catalyzes the breaking of peptide bonds that maintain the primary structure of a protein

Answer 18

proteolytic enzyme

Question 19

a molecule that inactivates enzymes by forming a strong covalent bond to an amino acid side-chain group at the enzyme’s active site

Answer 19

irreversible enzyme inhibitor