Chapter 11 Review

Question 1

Enzymes are _______ selective.

Answer 1

very

Question 2

Enzymes exhibit _________ and __________ complementary

Answer 2

electronic and geometric

Question 3

Oxidoreductase

Answer 3

Catalyzes oxidation-reduction reactions

Question 4

Transferase

Answer 4

Catalyzes group (functional groups) transfer reactions

Question 5

Hydrolase

Answer 5

Catalyzes hydrolysis reactions

Question 6

Lyase

Answer 6

Catalyzes group elimination to form double bond

Question 7

Isomerase

Answer 7

Catalyzes isomerization

Question 8

Ligase

Answer 8

Catalyzes the bond formation. Typically coupled to ATP hydrolysis.

Question 9

Cofactor + apoenzyme =

Answer 9

Holoenzyme

Question 10

Apoenzyme

Answer 10

Protein made. It is a not functioning enzyme when it doesn’t have a cofactor

Question 11

Cofactor

Answer 11

• Metal ions (can add structure support and enzymatic support)
• Coenzymes (typically some type of organic molecule)

Question 12

Coenzymes

Answer 12

• Cosubstrates (ex: NAD+)

- Prosthetic Group (Heme, Fe-S) –> Usually covalently bound to a substrate

Question 13

How does an enzyme lower the Ea?

Answer 13

• By bringing the functional groups together (proximity)

- Preferential binding

Question 14

The 5 types of Catalytic Mechanism:

Answer 14

1) Covalent Catalysis
2) Acid-Base Catalysis
3) Metal-Ion Assisted
4) Proximity and Orientation
5) Preferential binding to transition state

Question 15

What is covalent catalysis?

Answer 15

Enzyme covalently binds to substrate

1) Nucleophile attacks electrophile
2) Withdraw e- from a reaction center
3) Elimination of catalysis

Question 16

What is acid-base catalysis?

Answer 16

Protons are transferred

Question 17

What is metal-ion assisted catalysis?

Answer 17

Metal ions added to take/give e-

Question 18

What is proximity and orientation?

Answer 18

Lines them up for reaction to occur

Question 19

What is preferential binding to transition state?

Answer 19

Set up strain on bonds to force them to react. Enzymes bind to the planar transition state (lowers the TS).
-Drugs bind even tighter in transition state

Question 20

What is the proximity effect?

Answer 20

By simply having two binding sites within the active site, one for each substrate, reaction between the two substrates will proceed faster. Line up the e- orbitals overlap.
-Limiting-Step: binding/releasing of the enzyme

Question 21

What is orientation effect?

Answer 21

Enzymes bind substrates in proper orientation for reaction

Question 22

Keto-Enol Tautomerization

Answer 22

-Acid donates proton in first step and remove it again later
or
-Remove proton first and then add one later.

Question 23

In preferential binding, enzyme binds TS with ________ affinity (________) than substrate.

Answer 23

greater ; lower Kd