1.6-Enzyme Regulation

Question 1

What is the main reason for loss of enzyme activity?

Answer 1

Denaturation

Question 2

What is the term for and enzyme AND its cofactor?

Answer 2

A HoloEnzyme

Question 3

What is the term for just the protein portion of a holoenzyme?

Answer 3

An ApoEnzyme

Question 4

What is a tightly bound coenzyme that does not dissociate?

Answer 4

A Prosthetic Group

Question 5

What is the difference between a coenzyme and a cofactor?

Answer 5

Cofactor is more general and can include metals, molecules, etc. Coenzyme is generally organic in nature

Question 6

What are the three types of reactions involving enzymes?

Answer 6

1. Random 2.Sequential 3. Double Displacement (PingPong)

Question 7

What is Km for starch when introduced to the mouth?

Answer 7

Km is the concentration of starch when 1/2 of salivary amylase enzymes are taken up

Question 8

What is the name of the kinetic relationship between constant [enzyme] and varying [substrate]?

Answer 8

Michaelis-Menten Kinetics

Question 9

What are the three conditions for Michaelis-Menten Kinetics?

Answer 9

1. LOTS more fries then Pacmen 2. Once a pac man clamps down he won’t let go. 3. Only the INITIAL velocity is used

Question 10

If I have a substrate with a LARGE Km do I have a high or low affinity for that enzyme?

Answer 10

I have a LOW affinity.. Lots of fries to FINALLY reach the 1/2Vmax..

Question 11

What does a SMALL Km tell me about the affinity of a substrate to an enzyme?

Answer 11

Small Km = HIGH affinity of the substrate for the enzyme

Question 12

What is the double reciprocal plot that helps us determine Vmax?

Answer 12

A LineWeaver-Burke Plot

Question 13

What is Kcat?

Answer 13

TURNOVER NUMER. The number of Substrate converted to Product PER Enzyme. (SO, how efficient is my pac man at eating stuff)

Question 14

How do I find efficiency of my enzyme by relating Kcat to Km? What is the PERFECT enzyme?

Answer 14

Kcat/Km. The perfect enzyme will have a HIGH Kcat/LOW Km (so high turnover AND high affinity)

Question 15

What were our two examples for very SPECIFIC enzymes? What are they specific to?

Answer 15

Urease: Urea & Catalase: H2O2

Question 16

What was our example for a non specific enzyme?

Answer 16

CHYMO-trypsin

Question 17

What does an inhibitor do?

Answer 17

Diminishes the VELOCITY of an enzyme catalyzed reaction

Question 18

What kind of inhibition occurs when an enzyme does not regain activity upon dilution of the enzyme?

Answer 18

Irreversible Inhibition

Question 19

What are the two MAIN types of reversible inhibition? I’m ignoring uncompetitve :)

Answer 19

1. Competitive (@ active site) 2. Noncompetitive (Allosteric Site)

Question 20

What effect does a COMPETITIVE inhibitor have on Vmax? Km?

Answer 20

No change in Vmax with an inhibitor. Inhibitors INCREASE Km. (Need to have more S to get the same 1/2Vmax)

Question 21

What effect does a NONcompetitive inhibitor have on Vmax? Km?

Answer 21

DECREASES Vmax (Adding more S doesn’t do anything!). Km stays the same (S still binds to E).

Question 22

What must the body do to compensate for an enzyme being irreversibly blocked? Think aspirin…

Answer 22

The body must produce more enzyme (which will take a while :)

Question 23

What are the three CK (creatine kinase) Iso(en)zymes we discussed? Where can I find them?

Answer 23

BB in Brain, MB in Heart, MM in skeletal and heart muscle

Question 24

What is another word for proenzymes/prohormones?

Answer 24

Zy-Mo-Gens