Biochemistry
Agents That Affect Oxygen Binding
Compiled By Simon Mwangi
Edition: 2024/25
, Science | Biochemistry I of VI pages
1. What kind of protein is haemoglobin?
Allosteric protein that displays cooperativity in oxygen binding and release
2. Is the binding of oxygen by myoglobin cooperative?
No because it is a monomer (only one subunit)
3. What is oxygen binding measured as a function of?
The partial pressure of oxygen
4. What is the iron bound to in haemoglobin?
4 nitrogens
5. What is the 5th coordination site of iron occupied by?
Imidazole ring of a histidine (proximal histidine)
6. What binds to the 6th coordination site of iron?
Oxygen
7. What happens to the iron when oxygen binds to it?
It moves into the plane of the protoporphyrin ring which pushes amino acids to different position
8. What stabilises the bound oxygen?
The distal histadine
9. Why can fMRI distinguish the relative amounts of oxy- and deoxyhemoglobin?
Because the magnetic properties of the heme iron changes when it moves into the plane of the protoporphyrin
10. What is the concept called which makes heme have higher affinity for oxygen once one is bound?
Cooperativity
11. What kind of oxygen binding curve does myoglobin display?
Hyperbolic
12. What kind of oxygen binding curve does haemoglobin display?
Sigmoid curve which indicates that O2 binding and release is cooperative
13. When partial pressure of oxygen decreases, what happens to the affinity?
It also decreases
14. Is haemoglobin exposed to superoxide ions?
No
15. Why is it critical that oxygen is only released in the O2 and not superoxide state?
Superoxide is very reactive and will bind and harm other moleculesIron ion would be left in the ferric (Fe3+)
16. What is myoglobin called when iron ion is left in the ferric state (Fe3+), preventing additional oxygen
Metmyoglobin
Biochemistry 2024/25 Edition
Agents That Affect Oxygen Binding
Compiled By Simon Mwangi
Edition: 2024/25
, Science | Biochemistry I of VI pages
1. What kind of protein is haemoglobin?
Allosteric protein that displays cooperativity in oxygen binding and release
2. Is the binding of oxygen by myoglobin cooperative?
No because it is a monomer (only one subunit)
3. What is oxygen binding measured as a function of?
The partial pressure of oxygen
4. What is the iron bound to in haemoglobin?
4 nitrogens
5. What is the 5th coordination site of iron occupied by?
Imidazole ring of a histidine (proximal histidine)
6. What binds to the 6th coordination site of iron?
Oxygen
7. What happens to the iron when oxygen binds to it?
It moves into the plane of the protoporphyrin ring which pushes amino acids to different position
8. What stabilises the bound oxygen?
The distal histadine
9. Why can fMRI distinguish the relative amounts of oxy- and deoxyhemoglobin?
Because the magnetic properties of the heme iron changes when it moves into the plane of the protoporphyrin
10. What is the concept called which makes heme have higher affinity for oxygen once one is bound?
Cooperativity
11. What kind of oxygen binding curve does myoglobin display?
Hyperbolic
12. What kind of oxygen binding curve does haemoglobin display?
Sigmoid curve which indicates that O2 binding and release is cooperative
13. When partial pressure of oxygen decreases, what happens to the affinity?
It also decreases
14. Is haemoglobin exposed to superoxide ions?
No
15. Why is it critical that oxygen is only released in the O2 and not superoxide state?
Superoxide is very reactive and will bind and harm other moleculesIron ion would be left in the ferric (Fe3+)
16. What is myoglobin called when iron ion is left in the ferric state (Fe3+), preventing additional oxygen
Metmyoglobin
Biochemistry 2024/25 Edition
