1.3 Peptide Bond Formation and Hydrolysis [HY]

Question 1

What’re peptides made of?

Answer 1

amino acid subunits, sometimes called residues (COOH, NH2)

Question 2

How many AA residues do di and tripeptides have?

Answer 2

2 & 3

Question 3

Oligopeptide

Answer 3

used for relatively small peptides, up to about 20 residues

Question 4

Polypeptides

Answer 4

longer chains

Question 5

How are residues in peptides joined?

Answer 5

• through peptide bonds, a
  specialized form of an amide bond, which form between the −COO− group of one amino acid and the NH+3 group of another amino acid This forms the functional group −C(O)NH−.

Question 6

What kind of rxn is peptide bond formation?

Answer 6

• Condensation or dehydration
• Removes H20
• also be viewed as an acyl substitution reaction, which can occur with all
  carboxylic acid derivatives. (nucleophile displaces acyl derivative LG)

Question 7

What resonance is present in peptide bonds?

Answer 7

the C−N bond in the amide has partial double bond character and is therefore very restricted

Question 8

N-terminus

Answer 8

the free amino end when a peptide bond forms

Question 9

C-terminus

Answer 9

the free carboxyl end is the carboxy terminus

Question 10

How are peptides drawn and read?

Answer 10

• Left to right
• N to C terminus

Question 11

How’re proteins digested?

Answer 11

we need to break them down into their component amino acids

Question 12

How is hydrolysis catalyzed?

Answer 12

by hydrolytic enzymes such as trypsin and chymotrypsin

Question 13

How does trypsin cleave?

Answer 13

• at the carboxyl end of AA’s R, and K

Question 14

How does chymotrypsin cleave?

Answer 14

• at the carboxyl end of F, T and W

Question 15

How do enzymes catalyze hydrolysis?

Answer 15

they break apart the amide bond by adding a hydrogen atom to the amide nitrogen and an OH group to the carbonyl carbon
* Amide to NH3 & OH to H2O