Amino Acids and Peptides

Question 1

What is the pKa of the N-terminus on a amino acid?

Answer 1

~ 9.6

Question 2

What is the pKa of the C-terminus on a amino acid?

Answer 2

~ 2.3

Question 3

What configuration are all natural occurring amino acids in?

Answer 3

L- configuration (The body cannot break down D-configuration amino acids)

Question 4

Describe a disulfide bonds formation.

Answer 4

The thiol group of Cys can react with other Cys-SH groups to form a disulfide (–S-S–) bridge in proteins in an oxidation reaction.

Question 5

What is the pKa of Lysine (Lys)?

Answer 5

= 10.53

Question 6

What is the pKa of Arginine (Arg)?

Answer 6

= 12.48

Question 7

What is the pKa of Histidine (His)?

Answer 7

= 6.00

Question 8

Whtat is the pKa of Aspartate (Asp)?

Answer 8

= 3.65

Question 9

What is the pKa of Glutamate (Glu)?

Answer 9

= 4.25

Question 10

What are the essential amino acids?

Answer 10

Amino acids that the body cannot synthesize on its own, and therefore needs to be included in the diet.

Question 11

What are the major ionization states of amino acids?

Answer 11

Cationic form –> Zwitterion (neutral) –> Anionic form

Question 12

What is an isoelectric point (pI)?

Answer 12

pH where there is an equal amount of (+) and (-) charges (overall charge of zero).

Question 13

What kind of a reaction is a peptide bond formation.

Answer 13

A condensation reaction because it loses a water molecule.