Protein structure & function

Question 1

What is the structure of myoglobin?

Answer 1

Single subunit protein
One Haem group
Can bind one O2 molecule

Question 2

Does myoglobin show cooperativity?

Answer 2

Exhibits hyperbolic O2 binding with no cooperativity

Question 3

What is the structure of Haemoglobin?

Answer 3

Tetrameric protein (2 alpha, 2 beta subunits)
4 Haem groups
Can bind 4 O2

Question 4

What type of binding does Haemoglobin show?

Answer 4

Sigmoidal binding curve

Show cooperativity

Question 5

What is cooperativity?

Answer 5

Binding of a ligand makes the molecule more (or less) accepting of another ligand

Question 6

What are the 2 states of haemoglobin?

Answer 6

Tense

Relaxed

Question 7

What is myoglobins affinity for O2?

Answer 7

Very high, so will only release O2 when the pO2 is very low

Question 8

What is haemoglobins affinity for O2?

Answer 8

The affinity increases as more O2 binds

Question 9

What is the difference between haemoglobins states?

Answer 9

Relaxed state allows O2 to bind
Tense state is less likely to have O2 bind
Bidning of O2 encourages the relaxed state

Question 10

How does 2,3-bisphosphoglycerate effect O2 binding to haemoglobin?

Answer 10

Shifts curve to the right because it decreases the affinity of haemoglobin for O2

Question 11

How does CO2 and H+ effect O2 binding to haemoglobin?

Answer 11

Shifts curve to the right because it decreases the affinity of haemoglobin for O2