Enzymes

Question 1

Enzymes

Answer 1

biological catalysts

Question 2

coenzymes

Answer 2

ORGANIC molecules needed for optimal function of enzymes

Question 3

cofactor

Answer 3

IONS needed for optimal function of enzymes

Question 4

Enzyme specificity

Answer 4

enzymes can be specific for: substrate or the type of reaction they catalyze

Question 5

Oxidoreductases

Answer 5

oxidation- reduction reactions, transfer of electrons

Question 6

examples of oxidoreductases

Answer 6

• dehydrogenase,
• lactate dehydrogenase

Question 7

Transferases

Answer 7

group transfer other than hydrogen

Question 8

Examples of Transferases

Answer 8

• Hexokinase
• fructokinase
• glucokinase

Question 9

Hydrolases

Answer 9

Addition of water to remove bonds

Question 10

Examples of Hydrolases

Answer 10

• Lactase
• maltase

Question 11

Lyases

Answer 11

Bond breakdown without the addition of water.

Question 12

Examples of Lyases

Answer 12

• Aldolase
• Enolase

Question 13

Isomerases

Answer 13

Catalyze the isomerization of susbstrates, can be :

• optical
• positional
• geometrical

Question 14

Examples of isomerases

Answer 14

• Phosphohexose isomerase
• epimerase
• mutase
• racemase

Question 15

Ligases

Answer 15

• binding of two substrates
• need:
  
  • A TP
  • B iotin
  • C O₂

Question 16

Examples of ligases

Answer 16

• Acetyl CoA carboxylase
• pyruvate carboxylase

Question 17

Enzyme active site

Answer 17

• contains AAs chains that participate in substrate binding in catalysis
• Works by conformational change

Question 18

Catalysis is allowed by

Answer 18

induced conformational change

Question 19

What is the effect of an enzyme in the Energy of Activation?

Answer 19

Decreases Energy of Activation

Question 20

Substrate binding effect on the active site

Answer 20

induces the conformational change (induced- fit model - Koshland’s)

Question 21

Four ways an active site collaborates lowering the EA in order to reach the TS

Answer 21

1. stabilization of Transition State
2. expels water (better interaction)
3. provides reactive groups (additional bonds are formed)
4. provides a coenzyme/ cofactor which helps in catalysis

Question 22

Enzyme catalyzed reactions

Answer 22

• Increased rate of reaction
• Decreased Energy of Activation
• Total free energy (overall) stays equal

Question 23

Thermodynamics of a reaction

Answer 23

change in G < 0, spontaneous

change in G > 0, non- spontaneous

Change in G= 0, freely reversible

Question 24

What are the three most important factors that affect enzyme activity?

Answer 24

• Substrate concentration
• Temperature
• pH

Question 25

Enzyme Saturation Kinetics Plot

Answer 25

Assuming there is a fixed concentration of enzymes (as in the body)

• Initially, the reaction will proceed in a rapid rate as there are many more active sites than substrate. But not as at the max velocity bec not all active sites are occupied.
• As we add more substrate all active sites will be occupied and we will accomplish VMax
• Plateau: we added more substrate and there are more than active sites available and reaction rate will not increase unless more enzymes are added