Lectures 11,12,13: Enzymes

Question 1

Reversible inhibition

Answer 1

Binds to enzymes with non-covalent interactions (H+ bonds, hydrophobic, ionic bonds); don’t undergo chemical reactions when bound to enzyme, EASILY removed by dilution/dialysis

Question 2

Irreversible inhibition

Answer 2

Covalently modifies an enzyme, inhibition cannot be reversed - alter active site of target

Question 3

Oxidoreductases

Answer 3

Enzymes that catalyze oxidation-reduction reactions

Ex: alcohol dehydrogenase (ADH)

Question 4

Transferases

Answer 4

Enzymes that catalyze reactions which transfer functional groups from one molecule to another

Ex: kinase receptors

Question 5

Hydrolases

Answer 5

Enzymes that catalyze hydrolysis of covalent bonds

Ex: dissacharidases

Question 6

Lyases

Answer 6

Enzymes that catalyze addition or removal of groups to form double bonds

Ex: Aldolase

Question 7

Isomerases

Answer 7

Enzymes that catalyze isomerization

Ex: triose phosphate isomerase

Question 8

Ligases

Answer 8

Enzymes that catalyze covalent linkages of two substrates, usually at the expense of ATP hydrolysis

Ex: DNA ligase

Question 9

Competitive inhibition

Answer 9

Inhibitor competes with substrate for active site

Km is INCREASED, Vmax does not change

Question 10

Uncompetitive inhibition

Answer 10

Inhibitor does not effect ES complex formation; binds to a site other than the active site - only binds to ES complex

Both Km and Vmax are LOWERED by same factor

Question 11

Noncompetitive inhibition

Answer 11

Inhibitors that bind with both enzyme and ES complex

Vmax is LOWERED, Km unchanged