Test 2 - Enzymes (Corrected)

Question 1

Catalysis by proximity

Answer 1

• Substrate molecules are in the active site of enzymes
• Support:
  
  • If you can bring enzymes closer to their substrates, then the reaction will move faster.
  • In example C the esthers are already close to each other so they can be catalyzed faster.
• Role in Substrate Channeling
  
  • Substrates are channeled that way the concentration of substrates and intermediates is kept high as it moves from one enzyme to the next.

Question 2

Acid - Base Catalysis

Answer 2

• Side chains and prosthetic groups contribute to catalysis by acting as acids and bases.
  
  • Presence of Asp, Glu, Lys, Arg, His.

Question 3

Coenzyme A

Answer 3

• Transfers: Acyl groups
• Precursor: Pantothenic acid and other compounds.

Question 4

FAD

Answer 4

• Flavin Adenine dinucleotide
• Transfer: Electrons
• Precursor: Riboflavin (Vit. B2)

Question 5

Lipoate

Answer 5

• Transfers: Electrons and Acyl groups
• Precursor: No dietary

Question 6

NAD

Answer 6

• Nicotinamide adenine dinucleotide
• Transfer: Hydride Ion ( :H -)
• Precursor: Nicotinic Acid (Niacin)
• Mobile Universal electron carrier

Question 7

Thiamine pyrophosphate

Answer 7

• Transfer: Aldehydes
• Precursor: Thiamine (Vit. B1)

Question 8

Tetrahydrofolate

Answer 8

• Transfer: One carbon groups.

Question 9

What type of inhibition does this graph show?

Answer 9

Competitive

Question 10

What type of inhibition is this equation?

Answer 10

Competitive

Question 11

What type of inhibition is this graph

Answer 11

Mixed inhibition graph

Question 12

What type of inhibition is the following graph?

Answer 12

Uncompetitive

Question 13

What does competitive inhibition effect?

Answer 13

Negatively impacts Km

Question 14

What does mixed or noncompetitive inhibition effect?

Answer 14

Decreases maximum Velocity.

Question 15

What does uncompetitive inhibition affect?

Answer 15

Decreases both Km and Vmax.

Question 16

Catalysis by strain

Answer 16

• Enzymes bind substrate in an unfavorable conformation to weaken the bond and promote cleavage.
  
  • Eg. Stickase model

Question 17

Catalysis by proximity

Answer 17

• Effective concentration and orientation of substrate molecules in the active site speed up efficiency.
  
  • Eg. Substrate channeling by multi-enzyme complexes.

Question 18

Covalent catalyis

Answer 18

• Formation of a covalent bond between the enzyme and one or more groups or substrates to create a more reactive enzyme
  
  • Eg. group transfer reactions.
  • Often contain Ser or Tyr