Lectur 6AB

Question 1

When can hydrophilic side chains participate in ionic bonds and H bonding

Answer 1

When located interior or folded protein

Question 2

Pka of side chains of Asp, Glu, Lysine, Arginine, Histidine

and Amino and carboxyl ends overall

Answer 2

• Amino end pka = 8, carboxyl end = 3
• Asp and Glu pka = 4.1
• Lysine pKa = 10.8
• Arginine pka = 12.5
• Histidine pka = 6

Question 3

Amphipathic helices

Answer 3

Possess hydrophobic amino acids on one side and hydrophilic amino acids on the other
- membrane binding domains of peripheral membrane proteins

Question 4

Leucine zipper

Answer 4

Leucine occurs at every 7th position of alpha helix

• aliphatic side chains oriented same side of helix and interact to form coiled coil
• Nonpaired segments fit into major groove of DNA. Side chains and DNA bases interact