Quaternary Structure

Question 1

F-actin

Answer 1

• helical symmetry
  -2 right handed, intertwined strands
• 13 subunits per turn
• pitch of 715 A

Question 2

Cholera Toxin

Answer 2

• pentamer of 5 Beta subunits, subunits form a ring with C5 symmetry
• pore in the center of pentamer
• Combines one A subunit with B pentamer to form AB5 holotoxin

Question 3

GroEL/GroES

Answer 3

• Both GroEL rings and GroES have 7-fold C7 symmetry
• top GroEL ring is cis, bottom ring is trans
• size of pore is 10 A

Question 4

Hemocyanin

Answer 4

• hexamer with dihedral D3 symmetry
• each subunits is 75 kDa
• oxygen is bound by 2 Cu(I) ions, liganded by 6 histidines

Question 5

Hemoglobin

Answer 5

• 4 subunits, 2 alpha chains, 2 beta chains
  C2 symmetry
• transition from T to R includes rotation of 15 degrees of 2 lobes, symmetry is maintained

Question 6

ATCase

Answer 6

• dihedral D3 symmetry
  -12 subunits (6 regulatory chains, 6 catalytic chains)
• one regulatory chain consists of 2 domains

Question 7

Neurominidase

Answer 7

• tetramer with C4 symmetry
• 6 subunits that act as propellers, each subunit contains 4 beta strands

Question 8

Haemagglutinin

Answer 8

• trimer with C3 symmetry