Lecture 11 - Enzyme Mechanisms

Question 0

Electron- deficient functional group that accepts an electron pair from a nucleophile to form a bond

Answer 0

Electrophile (E)

Question 1

Electron-rich functional group that donates an electron pair with an electrophile to form a bond

Answer 1

Nucleophile (Nu:)

Question 2

True or false? A lower dielectric environment increases the strength of electrostatic interactions.

Answer 2

True

Question 3

What’s the difference between specific acid or base and general acid or base?

Answer 3

Specific acid (H3O+)
Specific base (-OH)
General acid is a proton donor
General base is a proton acceptor

Question 4

Bovine pancreatic protease that catalyzes the hydrolytic cleavage of peptide bond

Answer 4

Chymotrypsin

Question 5

Name the steps in each phase (phase 1 and 2) of the enzyme mechanism

Answer 5

1. Positioning
2. His 57 is general base
3. Nucleophilic attack
4. Covalent intermediate
5. His 57 is general acid

Question 6

What acts as a general base in chymotrypsin reaction to deprotonate the hydroxyl group of Ser-195 and make it a better nucleophile

Answer 6

His-57

Question 7

What acts as a nucleophile and attacks the carbonyl group forming a covalent bond with the carbonyl carbon = covalent catalysis

Answer 7

Ser-195

Question 8

What catalyzes the phosphorylation of glucose in a reversible reaction, involving Mg ion, ADP and ATP?

Answer 8

Hexokinase

Question 9

What’s the function of coenzymes?

Answer 9

Coenzymes aid in catalyzing reactions that could not be catalyzed with the functional groups present in amino acids

Question 10

Name some of the common biological nuclophiles?

Answer 10

Oxygen anion, sulfur anion, carbanion, nitrogen anion, imidazole, hydroxide

Question 11

Name some of the common biological electrophiles

Answer 11

Carbonyls, protonated imines, phosphorous in phosphate group, proton