Kaplan Ch. 2 - Enzymes

Question 1

Cofactor

Answer 1

Metal ion or inorganic group

Think “factory” —> manufacturing —> metal

Question 2

Coenzyme

Answer 2

Vitamins

Question 3

Holoenzyme vs. apoenzyme

Answer 3

Holo = enzyme + Co factor
Apo = enzyme only

Question 4

Zymogen

Answer 4

Name for an enzyme when it is secreted in its inactive form, regulatory portion of enzyme will be removed or altered to activate enzyme

Question 5

In enzyme kinetics, which step determines the Vmax?

Answer 5

The slowest step, rate limiting step. Note: Vmax is simply rate_max. Thus, if the limiting step is B—>

Question 6

What is Km equal to when the velocity = 1/2 max?

Answer 6

Km = [Substrate]

Question 7

4 types of reversible inhibition

Answer 7

Competitive
Uncompetitive
Non competitive
Mixed

Question 9

Uncompetitive inhibitor:

1) binds to ____ site
2) binds only when ___
3) effect on Vmax
4) effect on Km

Answer 9

1) binds to site other than active site of substrate
2) binds only to the ES complex
3) lowers Vmax
4) lowers Km (apparent increase in affinity of substrate for enzyme)

Question 10

Mixed Inhibition:

1) binds to ___ site
2) binds to enzyme when ___
3) effect on Vmax
4) effect on Km

Answer 10

1) binds to site other than active site of substrate
2) when it is either free enzyme or ES complex
3) decreases Vmax
4) depends - if inhibitor binds to ES complex then acts like uncompetitive inhibitor and lowers Km
If inhibitor binds to E then acts like competitive inhibitor and increases Km

Question 11

Non Competitive inhibitor:

1) sub class of _____ inhibition
2) effect on Vmax
3) effect on Km

Answer 11

1) mixed - can bind to E or ES
2) decreases
3) remains unchanged

Question 13

Competitive Inhibition:

1) inhibitor competes with ___ for the ___ and prevents ____
2) can be overcome by ___
3) effect on Vmax?
4) effect in Km?

Answer 13

1) substrate, active site, binding of substrate
2) adding more substrate
3) no change
4) increases (larger Km indicates decreased affinity for substrate)