Lecture 10 - Enzyme Mechanisms

Question 0

Which enzyme catalyzes the polymerization of nucleotides to form DNA?

Answer 0

DNA polymerase

Question 1

Why are enzymes central to all biochemical processes?

Answer 1

Enzymes show greater substrate specificity, and have an optimal arrangement of catalytic groups for chemical reaction

Enzymes increased reaction rates but not reaction equilibria

Question 2

List the inorganic ions that serve as cofactors for enzymes

Answer 2

Cu2+
Fe2+ or Fe3+
K+
Mg2+
Mn2+
Mo
Ni2+
Zn2+

Question 3

Interaction between substrate and enzyme is mediated by what?

Answer 3

The same noncovalent forces that stabilize protein structure

Question 4

Lowers energy of transition state making it easier to form

Answer 4

Transition state stabilization

Question 5

Arranges atoms for optimal activity

Answer 5

Orientation

Question 6

Binding removes interactions with solvent (water)

Answer 6

Desolvation

Question 7

Substrate binding changes conformation of enzyme

Answer 7

Induced fit

Question 8

What kind of catalysis pushes or pulls a proton?

Answer 8

Acid – base catalysis

Question 9

What kind of catalysis adducts or intermediates?

Answer 9

Covalent catalysis

Question 10

What kind of catalysis involves Lewis acid and redox agents?

Answer 10

Metal ion catalysis

Question 11

Energy derived from ES interaction is called what?

Answer 11

Binding energy (ΔGB)

Question 12

True or false? Enzymes use binding energy to achieve substrate specificity and to stabilize the transition states through noncovalent interactions.

Answer 12

True

Question 13

What kind of bonds or interactions are considered non-covalent interactions?

Answer 13

Hydrogen bonds
Ionic interactions
Hydrophobic interactions

Question 14

True or false? The mechanism of enzyme binding is a “lock and key” mechanism.

Answer 14

False, it is NOT

Question 15

True or false? Enzymes bind the transition state with a greater affinity than either substrates or products.

Answer 15

True

Question 16

Transition state analogues are good ________ of enzymes

Answer 16

Inhibitors

Question 17

Class of enzymes involved in transferring electrons

Answer 17

Oxidoreductases

Question 18

Class of enzymes involved in the group transfer reactions

Answer 18

Transferases

Question 19

Class of enzymes involved in hydrolysis reactions

Answer 19

Hydrolases

Question 20

Class of enzymes involved in the addition of groups to double bonds or double bond formation by removing groups

Answer 20

Lyases

Question 21

Class of enzymes involved in transfer of groups within a molecule to give an isomer

Answer 21

Isomerases

Question 22

Class of enzymes involved in the formation of C – C, C – S, C – O, and C – N bonds by condensation reactions coupled with ATP cleavage or similar cofactor

Answer 22

Ligases

Question 23

What’s the relationship between activation energy and rate?

Answer 23

The relationship is inverse and exponential. As activation energy decreases, the rate increases.