AA's & Proteins

Question 1

What is the pKa of the amine group in amino acids?

Answer 1

9

Question 2

What is the pKa of the carboxylic acid group in amino acids?

Answer 2

2

Question 3

What is the pKa of the R group in the 2 negatively charged amino acids?

Answer 3

4

Question 4

What is the pKa of the R group in lysine?

Answer 4

10

Question 5

What is the pKa of the R group in arginine?

Answer 5

12

Question 6

What is the pKa of the R group in histidine? What is special about this and how is it useful?

Answer 6

6.5, close to physiological pH so it exists in both protonated and deprotonated forms, making it useful at active sites where it can both stabilize and destabilize the protein

Question 7

Proline has what kind of amino group?

Answer 7

secondary alpha - meaning that the carbon chain loops around and makes a second bond with the N

Question 8

Glycine is the only amino acid that is …. ?

Answer 8

non-chiral (very flexible)

Question 9

Which 2 amino acids disrupt secondary protein structure?

Answer 9

glycine and proline introduce kinks into alpha helix

Question 10

What amino acid forms disulfide bridges?

Answer 10

Cysteine

Question 11

What type of environment do disulfide bridges form in? Where do you find this environment in the body?

Answer 11

oxidizing, extracellular

Question 12

What is the pKa of the R group in tyrosine?

Answer 12

10

Question 13

What is the pKa of the R group in cysteine?

Answer 13

8

Question 14

Which amino acids are polar?

Answer 14

Serine
Cysteine
Threonine
Asparagine
Glutamine

Question 15

Which amino acids are positively charged?

Answer 15

Arginine
Lysine
Histidine

Question 16

Which amino acids are non-polar and non-aromatic?

Answer 16

Glycine
Leucine
Alanine
Methionine
Valine
Isoleucine
Proline

Question 17

What are the aromatic amino acids?

Answer 17

Tryptophan
Phenylalanine
Tyrosine

Question 18

Primary protein structure

Answer 18

linear sequence of amino acids

Question 19

Secondary protein structure

Answer 19

H bonding

alpha helix
beta sheet

Question 20

tertiary protein structure

Answer 20

3D structure
hydrophobic interactions
salt bridges
H bonding
disulfide bonds

Question 21

quaternary protein structure

Answer 21

interactions between subunits

heat/solutes –> denature

Question 22

peptide bond formation is what type of reaction? what group attacks what?

Answer 22

condensation,

nucleophilic amino group attacks electrophilic carbonyl

Question 23

How are peptide bonds broken?

Answer 23

hydrolysis