Biochem Final

Question 1

General acid catalysis

Answer 1

H+ Transfer from acid

Decrease G of transition state

Question 2

General Base catalysis

Answer 2

H+ Abstraction by base

Decrease G of transition state

Question 3

Concerted Acid-Base catalysis

Answer 3

Combined; Can occur simultaneously or sequentially.

Question 4

Acid-base catalysis

Answer 4

pH sensitive

Question 5

Bovine pancreatic RNase A

Answer 5

RNA hydrolysis

2 His Residue (acid/base)

Question 6

Covalent (Nucleophilic) Catalysis

Answer 6

Transient formation of catalytic substrate covalent bond.
Features:
Nucleophilic
e- withdraw by enzyme

Question 7

Example of Covalent Catalysis?

Answer 7

Acetoacetate decarboxylase
Acetoacetate can spontaneously become Acetone + CO2
This happens in Type 1 Diabetics; and people on the keto diet.

Question 8

Acetate + Lysine

Answer 8

Lysine’s NH2 group causes it to form a Schiff Base (imino group).

Question 9

What is the best Nucleophile?

Answer 9

Cysteine

Question 10

Protonated refers to?

Answer 10

Acid

Question 11

Deprotonated refers to?

Answer 11

Base

Question 12

Metaloenzymes?

Answer 12

Metal ions
Roles in catalysis:
Substrate orientation
Redox Reactions (e- transfer)
Electrostatics--Stabilize or sheild charges

Question 13

Examples of Metaloenzymes? (CA)

Answer 13

Carbonic Anhydrase
Cofactor: Zn2+
Zn2+, polarizes water to form OH-, and orient it.

Question 14

Examples of Metaloenzymes? (RR)

Answer 14

Redox Reaction:
Chytochrome C (Fe2+)
Cytochrome C (Fe2+) ---> Cytochrome C (Fe3+)
Shuttles e-'s from Complex 3 to 4

Question 15

Example of Proximity and Orientation?

Answer 15

Imidazole reacting with p-nitrophenylacetate

Tethering of imidazole increases reaction rate ~25%.

Question 16

Transition State Binding

Answer 16

Transition State bound by the enzyme with a high affinity