lec 19 serine proteases

Question 1

What is the enzyme-substrate complex?

Answer 1

it is when an enzyme binds to its substrate

Question 2

what is the transition state?

Answer 2

it is a high energy state that enzymes must pass through to form products

Question 3

what is acid-base catalysis?

Answer 3

Enzyme catalysis involving proton donation or acceptance

Question 4

what is covalent-catalysis?

Answer 4

Enzyme catalysis involving the formation of covalent bonds with substrates

Question 5

what are serine proteases?

Answer 5

a type of enzyme that cleaves peptide bonds

Question 6

chymotrypsin is a serine protease that…

Answer 6

binds bulky hydrophobic side chains via its hydrophobic specificity pocket

Question 7

the catalytic triad is found in enzymes within the active site containing…

Answer 7

three amino acids known as serine, histidine, and aspertate

Question 8

what is the main purpose of the catalytic triad?

Answer 8

it cleaves peptide bonds

Question 9

what are the two stages of hydrolysis of chymotrypsin?

Answer 9

1. enzyme binds and forms covalent intermediate causing P1 to be released (fast step), while P2 is remains bound
2. P2 is released (slow step)

Question 10

what is the chymotrypsin reaction mechanism?

Answer 10

1. ES-complex
2. His57 removes proton from Ser195
3. His57 donates proton to amino group of substrate
4. water enters and his57 removes proton from it
5. His57 donates proton to ser195
6. functional triad is regenerated