Enzyme Kinetics

Question 1

What are kinetics?

Answer 1

The rate of a reaction

Question 2

Will enzyme activity increase when more substrate is added?

Answer 2

Yes, until it reaches saturation

Question 3

What is Vmax?

Answer 3

The reaction rate at saturation, when every active site is filled

Question 4

What type of curve will an enzyme with cooperativity have?

Answer 4

Sigmoidal

Question 5

What is Km?

Answer 5

The Michaelis constant. Indicates affinity of the enzyme

Question 6

What is the relationship between Km and substrate affinity?

Answer 6

High Km = low affinity

Low Km = high affinity

Question 7

Why is it hard to determine Vmax from an MM graph?

Answer 7

Asymptotic relationship, not linear

Question 8

What is the Y-intercept in an LB graph?

Answer 8

1/Vmax

Question 9

What is the X-intercept in an LB graph?

Answer 9

-1/Km

Question 10

What is the slope in an LB graph?

Answer 10

Km/Vmax

Question 11

Where does a competitive inhibitor bind?

Answer 11

Active site. It looks very similar to the substrate and actively competes with it for the active site

Question 12

How does a competitive inhibitor affect Vmax and Km?

Answer 12

Vmax doesn’t change, but Km will increase

Question 13

What happens to enzyme activity when an allosteric modifier binds?

Answer 13

Activity can either increase or decrease, depends on what the molecule is

Question 14

Where does a non-competitive inhibitor bind?

Answer 14

Allosteric site. It changes the conformation of the active site so the substrate will bind but can’t react

Question 15

How does a non-competitive inhibitor affect Vmax and Km?

Answer 15

Vmax changes, but Km doesn’t

Question 16

What is feedback inhibition?

Answer 16

Buildup of a downstream product will slow down upstream reactions

Question 17

How do we predict which metabolic pathway a substrate will go into?

Answer 17

Calculate Vmax and Km

Question 18

What determines if pyruvate will enter fermentation or CAC?

Answer 18

Presence of oxygen

Question 19

What are allosteric activators of glycolysis?

Answer 19

CoA, AMP, ADP, NAD+

Question 20

What are allosteric inhibitors of glycolysis?

Answer 20

Acetyl-CoA, Citrate, ATP, NADH

Question 21

What are the 3 metabolic pathways that oxaloacetate can go into?

Answer 21

CAC, aspartate biosynthesis, gluconeogenesis

Question 22

What enzyme uses oxaloacetate in the CAC?

Answer 22

Citrate synthase

Question 23

What are the allosteric inhibitors of the CAC?

Answer 23

ATP, acetyl-CoA, succinyl-CoA, NADH

Question 24

What enzyme uses oxaloacetate in gluconeogenesis?

Answer 24

Carboxykinase

Question 25

What is the allosteric inhibitor of gluconeogenesis?

Answer 25

DPNH

Question 26

What enzyme uses oxaloacetate in aspartate biosynthesis?

Answer 26

Aspartate amino transferase

Question 27

What determines if oxaloacetate will go into the CAC, gluconeogenesis, or Asp biosynthesis?

Answer 27

Km, which will change depending on what the cell needs