Lecture 9.29.14 (Ch.9 Enzyme Catalysis)

Question 1

Acidic Residue

Answer 1

Neutral to Negative

Question 2

Acidic Residue want charge…

Answer 2

pka decrease

Question 3

Acidic Residue not want charge

Answer 3

pka increase

Question 4

catalytic residue (4)

Answer 4

amino acid side chain in the active site that is involved in:

• mechanism
• altering the pka of a residue
• weakens covalent bonds
• stabilize transition state

Question 5

Basic Residue

Answer 5

Charged to Neutral

Question 6

Basic Residue want charge….

Answer 6

pka increase

Question 7

Basic Residue not want charge…

Answer 7

pka decrease

Question 8

Nucleophile

Answer 8

nucleus loving
has extra electrons
atoms with lone pairs

Question 9

Electrophile

Answer 9

electron loving
has lack of electrons
atoms with plus charge

Question 10

proteases

Answer 10

enzymes that hydrolyze peptide bonds

Question 11

Strategies used for enzyme catalysis

Answer 11

covalent catalysis

acid-base catalysis

Question 12

covalent cataylsis

Answer 12

the active site contains a reactive group, usually a nucleophile, that becomes temporarily covalently attached to part of a substrate

ex. chymotrypsin

Question 13

acid-base catalysis

Answer 13

a molecule other than water plays the role of a proton donor or acceptor

Question 14

chymotrypsin cleaves peptide bonds from the ______?

Answer 14

carboxyl terminal side of large hydrophobic amino acids

Question 15

which amino acids are cleaved by chymotrypsin?

Answer 15

tryptophan, tyrosine, phenylalanine, methionine, and leucine

Question 16

which residue plays a central role in the mechanism of chymotrypsin?

Answer 16

serine residue

Question 17

What are the 2 phase of chymotrypsin hydrolysis?

Answer 17

1. Acylation to form the acyl-enzyme intermediate followed by
2. deacylation to regenerate the free enzyme

Question 18

Types of proteases? (4)

Answer 18

serine
metallo
cystetine/thiol
acid/aspartic

Question 19

A basic amino acid is always acting like an

Answer 19

ACID

Question 20

An acid amino acid is always acting like a

Answer 20

BASE

Question 21

Acid

Answer 21

H+ donor, electron acceptor

Question 22

Base

Answer 22

H+ acceptor, electron donor

Question 23

Metallo proteases

Answer 23

metal(Zn) activates electrophile

Question 24

Carboxypeptidase A (CPA) cuts off

Answer 24

C terminal residue

ex. AFRIDAY-> AFRIDA & Y

Question 25

CPA needs ______ to function and fold

Answer 25

Zn+2 (as acts an acid)

Question 26

What type of intermediate in involved in CPA?

Answer 26

tetrahedral

Question 27

Typsin cleaves

Answer 27

Bases

Lysine and Arginine

Question 28

Elastase cleaves

Answer 28

No polar aliphatic

Glycine and Alanine