Enzyme Regulation

Question 1

zymogen

Answer 1

an inactive protein precursor

Question 2

prothrombin

Answer 2

precursor of thrombin, involves two cleavages, one that releases enzyme from the membrane the other involves proper active site formation

Question 3

Vitamin K

Answer 3

cofactor required for the gamma-carboxylation of a glutamate residue on prothrombin

Question 4

warfarin

Answer 4

a vitamin K analog that inhibits the gamma-carboxylation reaction and reduces the amount of active thrombin that can be made

Question 5

antithrombin

Answer 5

inactivates thrombin by binding strongly to it

Question 6

elastase

Answer 6

a serine protease released by neutrophils and degrades elastin fibers

Question 7

alpha1-antittrypsin

Answer 7

an elastase inhibitor

Question 8

amino acids that can be modified by phosphorylation

Answer 8

serine, threonine, and tyrosine

Question 9

competitive inhibitors

Answer 9

reversible enzyme inhibitors that compete with the active site of the substrate

Question 10

Competitive inhibitors alter the (Km/Vmax)

Answer 10

Km

Question 11

Noncompetitive inhibitors

Answer 11

inhibitors that do not bear resemblance to the substrate and bind to a different location on the enzyme

Question 12

Noncompetitive inhibitors alter the (Km/Vmax)

Answer 12

Vmax

Question 13

DIFP

Answer 13

a potent irreversible inhibitor of serine proteases

Question 14

effector

Answer 14

changes the activity of an enzyme by binding to it allosterically

Question 15

activators

Answer 15

positive effectors

Question 16

feedback inhibition

Answer 16

when one of the effectors is the end product of a reaction sequence and regulates the reaction

Question 17

PFK1 (phosphofructosekinase 1)

Answer 17

an allosteric enzyme that is involved in glycolysis, is inhibited by high levels of ATP