Unit 2

Question 1

Explain the cooperative O2 binding

Answer 1

Binding of O2 results in Fe moving up into porphyrin plane to coordinate

Coordinated proximal histidine is pulled w/ Fe ion → conformational change that is transmitted to other subunits → changes the O2 binding affinity of deoxygenated Fe centres w/in the protein

As O2 begins to bind to deoxyHb in T state, eqm shifts more and more over to R state ∴ see a change from easy O2 loss to high O2 uptake

Question 2

What is the Bohr effect

Answer 2

At low pH Hb affinity for O2 decreases (at ↑ [H+])
2. At ↑ pH or low conc [H+], Hb affinity for O2 ↑

Disease where pH of blood = ↓ → respiratory acidosis

CO = better pi acceptor than O2 → binds better w/ Hb ∴ cooperative effect ↑
Due to strong binding, liberation in tissues = difficult

Question 3

Name 4 enzymes involved in iron storage and transport

Answer 3

Haemoglobin, myoglobin, hemocyanin and hemerythrin