2.4 lecture

Question 1

What do enzymes do?

Answer 1

-They act as catalysts and lower activation energy
-equilibrium is reached faster

Question 2

What don’t enzymes do?

Answer 2

-does not change equilibrium points for reactions
-does not shift equilibrium toward more product

Question 3

Mechanisms enzymes use to lower activation energy?

Answer 3

1.catalytically active groups (polar/charged)
2.properly aligning groups
3.more weak intermolecular reactions are formed between enzyme and transition state

Question 4

Proteases

Answer 4

Cleave peptide bonds in the backbone of proteins

Question 5

Chymotrypsin structure

Answer 5

• 2 anti parallel beta barrel domains that sandwich together

Question 6

What are the structural requirements for chymotrypsin activity

Answer 6

1. catalytic triad
2. oxyanion hole
3. substrate binding pocket
4. specificity pocket

Question 7

catalytic triad

Answer 7

1. Serine (Ser)
2. Histidine (His)
3. Aspartate (Asp)

Question 8

Serine 95: catalytic triad

Answer 8

forms alkoxide ion that acts as a nucleophile and covalently bonds w/ the substrate

Question 9

Histidine 57: catalytic triad

Answer 9

acts as a general base to ionize the serine side chain and turns it into nucleophilic alkoxide

Question 10

Aspartate 102: catalytic triad

Answer 10

Stabilizes the positively charged histidine

Question 11

Oxyanion hole

Answer 11

formation of tetrahedral state

Question 12

Substrate binding pocket

Answer 12

binds peptide chains regardless of amino acid content

Question 13

Specificity pocket: Chymotrypsin

Answer 13

cuts after a bulky residue (F,Y,W)

Question 14

Specificity pocket: Trypsin

Answer 14

cuts after a positively charged residue (K, R)

Question 15

Specificity pocket: Elastase

Answer 15

cuts after small hydrophobic amino acids (A, V, G)

Question 16

Transition state

Answer 16

Transient and unstable

Question 17

Characteristics of enzyme inhibitors that are drugs

Answer 17

1. they are substrate/transition state mimics
2. They are more stable than the transition state
3. They block the enzyme activity site

Question 18

Ornithine decarboxylase

Answer 18

-produce polyamines
-anti-trypanosome drugs

Question 19

Where does HIV protease cut?

Answer 19

between F and P

Question 20

Protease inhibitors from plants

Answer 20

PIN I and PIN II
-inhibits serine proteinases